VS V8 complete and comprehensive DTC/Error codes list

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DTC 12:
System passed (OK)

DTC 13:
NO OXYGEN SENSOR SIGNAL

The exhaust oxygen sensor is mounted in the exhaust pipe with the sensing portion exposed to exhaust gases. After the sensor is hot (360 degrees C), it becomes a voltage generator, producing a "changing" voltage. This voltage ranges from approximately 100 millivolts with a "lean" exhaust, to 900 millivolts with a "rich" exhaust. When the sensor is cold (below 360 degrees C), it acts like an open circuit and produces almost no voltage. The PCM supplies a very small "bias" voltage between terminals C13 and C14, normally about 450 millivolts. If measured with the 10 megohm digital voltmeter, it may measure as low as 350 millivolts. When the sensor is hot, it's output overshadows this PCM supplied voltage.

When the fuel system is correctly operating in the closed-loop mode, the sensor output is changing several times per second, going above and below a mid-point range of 390-430 millivolts. The PCM compares the voltage between the sensor signal and sensor earth terminals and decides the needed fuel mixture correction. The PCM also monitors the changing voltage, watching for transitions above and below the mid-point range, to decide when to operate in the closed-loop mode. An open circuit, defective, or contaminated sensor could cause the voltage to stay within a 347-550 millivolt band too long, keeping the system in open-loop and setting a DTC 13.

DTC 13 will set if no DTC 21 or DTC 22 is active and all conditions exist for 20 seconds:
Engine has been running for at least 2 minutes, and
Engine coolant temperature is more than 85 degrees C, and
Throttle Position (TP) sensor voltage indicates the throttle is open more than 6%, and O2 sensor voltage stays between 347 - 550 millivolts.
*When DTC 13 is active (MIL) ("Check Powertrain" lamp "ON"), the PCM will operate the fuel system in the open-loop mode.

Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.
2. The Tech 1 "Scan" tool allows you to read the same oxygen sensor voltage the PCM is using for its calculations.
3. This step simulates a lean exhaust indication to the PCM. If the PCM and wiring are OK, the PCM will see the lean indication and the Tech 1 "Scan" tool should display O2 voltage below 200 mV.
8. In doing this test, use only a high impedance digital volt-ohm meter. This test checks the continuity of circuits 412 and 150. If circuit 150 is open, the PCM voltage on circuit 412 will be over 0.6 volts (600 mV).
9. Earth circuit 150 is a separate wire to the PCM from the engine. The PCM uses this circuit to compare it with the voltage on circuit 412. It completes the earth path for the PCM's oxygen sensor circuitry, and must be a complete, clean, and tight connection to the engine.

DTC 14:
ENGINE COOLANT TEMPERATURE (ECT) (SIGNAL VOLTAGE LOW)

The Engine Coolant Temperature (ECT) sensor uses a thermistor to control the signal voltage to the PCM. The PCM applies about 5 volts on circuit 410 to the sensor. When the engine coolant is cold, the sensor (thermistor) resistance is high, therefore the PCM will see high signal voltage about 4.0 - 4.5 volts.
As the engine coolant warms, the sensor resistance becomes less, and the PCM sees a lower signal voltage. At normal engine operating temperature (85 degrees C to 95 degrees C), the voltage should measure about 1.5 to 0.9 volts.

A DTC 14 may enable TCC operation when cold.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. DTC 14 will set if:
Time since engine started is greater than 10 seconds and
ECT sensor signal voltage is less than 0.3 volts, indicating an engine coolant temperature above 140 degrees C for one second.
3. This test will determine if circuit 410 is shorted to earth which will cause the conditions for DTC 14.
4. If checking resistance at the engine coolant temperature sensor is difficult because of sensor location, disconnect the PCM connectors and check resistance between engine coolant temperature signal and sensor earth terminals.

DTC 15:
ENGINE COOLANT TEMPERATURE (ECT) (SIGNAL VOLTAGE HIGH)

The Engine Coolant Temperature (ECT) sensor uses a thermistor to control the signal voltage to the PCM. The PCM applies about 5 volts on circuit 410 to the sensor. When the engine coolant is cold, the sensor (thermistor) resistance is high, therefore the PCM will see high signal voltage, about 4 - 4.5 volts.
As the engine coolant warms, the sensor (thermistor) resistance becomes less, and the PCM sees a lower signal voltage. At normal engine operating temperature (85 degrees C to 95 degrees C), the voltage will measure about 1.5 to 0.9 volts.

A Diagnostic Trouble Code 15 may enable TCC operation when cold.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
1. DTC 15 will set if:
Time since engine started is greater than 60 seconds, and
ECT input signal voltage is greater than 4.74 volts, indicating an engine coolant temperature less than -35 degrees C for one second
2. This test simulates a Diagnostic Trouble Code 14. If the PCM recognises the low signal voltage, (high temperature) and the Tech 1 "Scan" tool reads 130 degrees C or above, the PCM and wiring are OK.
3. This test will determine if circuit 410 is open. There should be an open circuit voltage of 5 volts present at Engine Coolant Temperature (ECT) sensor harness connector if measured with a DVM. By jumpering this 5 volt signal to earth, the PCM should recognise this change.

DTC 16:
ENGINE COOLANT TEMPERATURE (ECT) (SIGNAL VOLTAGE UNSTABLE)

The Engine Coolant Temperature (ECT) sensor is a thermistor located in a coolant passage on the engine. When engine coolant temperature is cold, the sensor has a high resistance. As temperature increases, the resistance of the sensor decreases. The PCM provides a five volt signal to the engine coolant sensor, which is also connected to PCM earth. The PCM reads the voltage drop on the signal line to determine engine coolant temperature.

Test Description: Numbers below refer to step(s) on the diagnostic chart.
2. Diagnostic Trouble Code 16 will set if:
The engine has been operating for more than one minute, and
ECT reading changes more than 15 degrees C in 100 milliseconds.

DTC 17:
PCM ERROR - ECT CIRCUIT

The PCM uses two different internal pull-up resistors to increase resolution throughout the entire range of engine operating temperatures. When the engine coolant temperature is less than 50 degrees C, the 4K ohm resistor is used. When temperature is above 50 degrees C, the PCM switches to the 348 ohm resistor. If the pull-up resistor does not switch, DTC 17 will set.

Test Description: Number(s) below refer to step(s) on the diagnostic chart.
2. DTC 17 will set if:
The engine has been operating for more than one minute, and
The pull-up resistor inside the PCM switches and there is no change in the engine coolant temperature signal.

Diagnostic Aids:
DTC 17 is an internal fault within the PCM. The PCM must be replaced!

DTC 19:
TP SENSOR STUCK

The Throttle Position (TP) sensor provides a voltage signal that changes relative to the throttle blade angle. Signal voltage will vary from about 0.25 to 1.25 volts at idle to approximately 5 volts at Wide Open Throttle (WOT).
The TP sensor signal is one of the most important inputs used by the PCM for transient fueling and transmission control and for most of the PCM control outputs.
Diagnostic Trouble Code (DTC) 19 is used to detect a stuck open or TP sensor. DTC 19 detects if the TP sensor does not return with the throttle blade when decelerating.

Diagnostic Trouble Code 19 will set if:
The Throttle Position (TP) sensor percentage of opening angle indicated is greater than the RPM that can be reached with a manifold absolute pressure reading less than 65 kPa for 10 seconds.
For example: If the TP sensor indicated that the angle of opening is greater than 3% and the engine is operating at 800 RPM or less, with a MAP sensor reading of 65 kPa or less (No Load) then the TP sensor is stuck open.

DTC 21:
THROTTLE POSITION (TP) (SIGNAL VOLTAGE HIGH)

The Throttle Position (TP) sensor provides a voltage signal that changes relative to the throttle blade angle. TP sensor signal voltage will vary from about 0.25 to 1.25 volts at idle to about 4 volts at Wide Open Throttle (WOT).
The TP sensor signal is one of the most important inputs used by the PCM for fueling and transmission control and for most of the PCM control outputs.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. DTC 21 will set if:
TP sensor signal voltage is greater than 4.9 for two seconds.
3. With the TP sensor disconnected, the TP sensor signal voltage should go low if the PCM and wiring are OK.
4. Probing circuit 452 with a test light connected to 12 volts checks the sensor earth circuit. A faulty sensor earth will cause a DTC 21.

DTC 22:
THROTTLE POSITION (TP) (SIGNAL VOLTAGE LOW)

The Throttle Position (TP) sensor provides a voltage signal that changes relative to the throttle blade. Signal voltage will vary from about 0.25 to 1.25 volts at idle to about 5 volts at Wide Open Throttle (WOT).
The TP sensor signal is one of the most important inputs used by the PCM for transient fueling and transmission control and for most of the PCM control outputs.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. DTC 22 will set if:
TP sensor signal input voltage is less than about 0.2 volts for two seconds.
3. This test simulates a Diagnostic Trouble Code 21: (high voltage) If the PCM recognises the high signal voltage and the Tech 1 "Scan" tool reads over 4 volts or above, the PCM and wiring are OK.
4. This simulates a high signal voltage to check for an open in circuit 417. The Tech 1 "Scan" tool will not read up to 12 volts, but what is important is that the PCM recognises the signal on circuit 417.

DTC 23:
INTAKE AIR TEMPERATURE (IAT) (SIGNAL VOLTAGE HIGH)

The Intake Air Temperature (IAT) sensor uses a thermistor to control the signal voltage to the PCM. The PCM applies a voltage (about 5 volts) on circuit 472 to the sensor. When the intake air is cold, the sensor (thermistor) resistance is high, therefore, the PCM will sensor a high signal voltage. If the intake air is warm, the sensor (thermistor) resistance is low, therefore, the PCM will sense a low signal voltage.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2.DTC 23 will set if:
IAT sensor signal voltage is more than 4.9 volts, indicating an intake air temperature below -38 degrees C.
3. A Diagnostic Trouble Code 23 will set, due to an open sensor, wire or connection. This test will determine if the wiring and PCM are OK.
6. This will determine if the IAT sensor signal (circuit 472) or the IAT sensor earth (circuit 469) is open.

DTC 24:
NO VEHICLE SPEED SIGNAL

The vehicle speed sensor circuit consists of a magnetic induction type sensor, and wiring. Gear teeth cut in the outside diameter of the output shaft alternately interrupt the permanent magnetic field inducing an alternating voltage in the sensor. This voltage is transmitted to the PCM to determine vehicle speed. The speedometer applies 12 volts on circuit 123. The PCM alternately earths circuit 123 when the drive wheels are turning. This pulsing action takes place about 6250 times per kilometre and the speedometer, BCM and trip computer will calculate vehicle speed based on the time between "pulses."

Test Description: Number(s) below refer to Step number(s) on the diagnostic chart.
1. Diagnostic Trouble Code 24 will set if:
Range selected is not in park or neutral.
Engine speed is greater than 3000 RPM.
Transmission output is less than 250 RPM.
TP sensor between 0% and 100%.
MAP sensor signal between 52 kPa to 100 kPa.
All conditions above met for about 3 seconds.

DTC 24 Will set if the VSS circuit is open from a standing stop. As the vehicle is accelerated the transmission will shift from 1st to 2nd gear at approximately 54 km/h. If the VSS signal is not present, DTC 24 will be set.
4. Output voltage will vary with speed from a minimum of 0.5 volts AC at 100 RPM, to more than 100 volts AC at 8000 RPM, with no load on the circuit on the vehicle, with the engine at 4000 RPM and in 4th gear, the voltage will be approximately 25 volts AC.
6. Diagnostic Trouble Code 24 is being caused by a faulty PCM, faulty PROM or an incorrect PROM.

Diagnostic Aids:
Check circuit 831 and 832 for proper connections to be sure they are clean and tight and the harness is routed correctly.
The Tech 1 "Scan" tool should indicate a vehicle speed whenever the drive wheels are turning greater than 3 km/h.
When Diagnostic Trouble Code 24 is set, the transmission will have high line pressure and 2nd gear only.
Vehicle speed sensor resistance should be 1260-1540 ohms when measured at 20 degrees C.

DTC 25:
INTAKE AIR TEMPERATURE (IAT) (SIGNAL VOLTAGE LOW)

The Intake Air Temperature (IAT) sensor uses a thermistor to control the signal voltage to the PCM. The PCM applies a voltage (about 5 volts) on circuit 472 to the sensor. When manifold intake air is cold (such as when the engine is first started on a cold day), the sensor (thermistor) resistance is high, therefore, the PCM will sense a high signal voltage. If the manifold intake air is warm, the sensor (thermistor) resistance is low, therefore, the PCM will sense a low signal voltage.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. DTC 25 will set if:
Engine has been operating for more than 60 seconds, and
Intake Air Temperature (IAT) signal voltage is less than 0.3 volts, indicating an intake air temperature above 135 degrees C.

DTC 26:
INTAKE AIR TEMPERATURE (IAT) (SIGNAL VOLTAGE UNSTABLE)

The Intake Air Temperature (IAT) sensor is a thermistor located in the intake manifold. When the intake air temperature is cold, the sensor has a high resistance. As temperature increases, the resistance of the sensor decreases. The PCM provides a five volt signal to the intake air temperature sensor which is also connected to PCM earth. The PCM reads the voltage drop on the signal line to determine intake air temperature.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. Diagnostic Trouble Code 26 will set if:
IAT Sensor reading changes more than 15 degrees C in 100 milliseconds.

DTC 28:
TRANSMISSION FLUID PRESSURE SWITCH ASSEMBLY (PSA) CIRCUIT SHORT

The Pressure Switch Assembly (PSA) is actually five pressure switches combined into one unit and mounted on the valve body. The PCM supplies battery voltage to the Pressure Switch Assembly (PSA) on three separate wires. By earthing one or more of these circuits through various combinations of the pressure switches inside the pressure switch assembly the PCM detects what gear range has been selected by the vehicle operator.

Test Description: Number(s) below refer to step number(s) on the diagnostic table.
2. This test compares the indicated range to the range actually selected.

DTC 31:
THEFT DETERRENT SIGNAL MISSING

When the ignition is turned "ON", the PCM will send a message on circuit 1221 to the BCM asking for permission to start. When the BCM receives this message, it instantly enables the starter and sends a message back to the PCM. The message says that the proper ignition key has been used to turn the ignition and that it is OK for the PCM to enable the fuel injectors to start the vehicle. If the BCM does not receive communications from the PCM when the ignition is switched "ON", then the starter motor will be enabled after a one second delay.

DTC 31 will be set, if the PCM sends 20 messages to the BCM and does not receive a message back saying it is OK to start.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. If the engine cranks after a one second delay it means the BCM did not see a message from the PCM when the ignition was turned "ON".
3. An open or short to earth on circuit 1221 will disable any communication of serial data.

DTC 33:
MANIFOLD ABSOLUTE PRESSURE (MAP) (SIGNAL VOLTAGE HIGH)

The Manifold Absolute Pressure (MAP) sensor responds to changes in manifold pressure (vacuum). The PCM receives this information as a signal voltage that will vary from about 0.8 - 1.5 volts at idle to 4 - 4.5 volts at Wide Open Throttle (WOT). The PCM uses this information for fuel and spark control.
The Tech 1 "Scan" tool displays manifold pressure in volts. Low pressure (high vacuum) reads a low voltage while a high pressure (low vacuum) reads a high voltage.
If the MAP circuit fault is detected, the PCM will substitute a MAP "default" value based upon Throttle Position (TP) sensor and RPM plus offset modifiers when in P/N or if A/C is "OFF" on "ON" to control fuel delivery.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
3. DTC 33 will set when:
Engine has been running.
TP sensor less than about 3%.
MAP sensor signal voltage is too high, (greater than 88 kPa of pressure) for a time greater than three seconds.
Engine misfire or low, unstable idle may set DTC 33. Disconnect the MAP sensor and the system will go into backup fuel mode.
4. If the PCM recognises the low MAP signal, the PCM and wiring are OK.
6. Check vacuum hose to MAP sensor for leaking or restriction.

DTC 34:
MANIFOLD ABSOLUTE PRESSURE (MAP) (SIGNAL VOLTAGE LOW)

The Manifold Absolute Pressure (MAP) sensor responds to changes n manifold pressure (vacuum). The PCM receives this information as a signal voltage that will vary from about 0.8 - 1.5 volts at idle to 4 - 4.5 volts at Wide Open Throttle (WOT).
The Tech 1 "Scan" tool displays manifold pressure in voltage. Low pressure (high vacuum) reads a low voltage while a high pressure (low vacuum) reads a high voltage.
If the MAP circuit fault is detected, the PCM will substitute a MAP "default" value and uses the Throttle Position (TP) sensor and RPM plus offset modifiers when in P/N or if A/C is "OFF" or "ON" to control fuel delivery.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. DTC 34 will set when:
Engine speed is less than 1200 RPM, and
MAP sensor signal voltage is too low (less than 14 kPa of pressure) for less than one second – OR - Engine speed is greater than 1200 RPM, and
Throttle position is greater than 20%, and
MAP sensor signal voltage is too low (less than 14 kPa of pressure) for less than one second.
3. If the PCM recognises the high MAP signal, the PCM and wiring are OK.
4. The Tech 1 "Scan" tool may not display 12 volts. The important thing is that the PCM recognises the voltage as more than 4 volts, indicating that the PCM and circuit 432 are OK.

DTC 35:
IDLE SPEED ERROR

DTC 35 will set when the closed throttle engine speed is 200 RPM above or below the desired (commanded) idle speed as determined by the PCM for 50 seconds. Review the general description of the Idle Air Control (IAC) valve operation in 1.2 Fuel Control System.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. The Tech 1 "Scan" tool RPM control mode is used to extend and retract the IAC valve. The valve should move smoothly within the specified range. If the idle speed is commanded (IAC extended) too low (below 700 RPM), the engine may stall. This may be normal and would not indicate a problem. Retracting the IAC beyond its controlled range (above 1500 RPM) will cause a delay before the RPM's start dropping, this too is normal.
3. This test uses the Tech 1 "Scan" to command the IAC controlled idle speed. The PCM issues commands to obtain commended idle speed. The test lights each should flash indicated a good circuit as the PCM issues commands. While the sequence is not important, if either light is "OFF" or does not flash, check the circuits for faults, beginning with poor terminal contacts.

Diagnostic Aids:
A slow, unstable, or fast idle may be caused by a non-IAC system problem that cannot be overcome by the IAC valve. Out of control range IAC Tech 1 "Scan" tool counts will be above 60 if idle is too low and zero counts if idle is too high. The following checks should be made to repair a non-IAC system problem:

Vacuum Leak (High Idle).
If idle is too high, stop the engine. Fully extend (low) IAC with Tech 1 "Scan" tool. Start engine.
If idle speed is above 800 RPM, locate and correct vacuum leak including PCV system. Also, check for binding of throttle blade or linkage.

System too lean (High Air/Fuel Ratio).
The idle speed may be too high or too low. Engine speed may be too high or too low. Engine speed may vary up and down and disconnecting the IAC valve does not help. DTC 44 may be set. Tech 1 "Scan" tool O2 voltage will be less than 300 mV. Check for low regulated fuel pressure, water in the fuel or a restricted injector.

System too rich (Low Air/Fuel Ratio).
The idle speed will be too low. Tech 1 "Scan" tool IAC counts will usually be above 80. System is obviously rich and may exhibit black smoke in exhaust. Tech 1 "Scan" tool O2 voltage will be fixed above 800 mV. Check for high fuel pressure, leaking or sticking injector. Silicon contaminated O2 sensor Tech 1 "Scan" tool voltage will be slow to respond.

Throttle Body.
Remove IAC valve and inspect bore for foreign material.
IAC Valve Electrical Connections.
IAC valve connections should be carefully checked for proper contact.

PCV Valve.
An incorrect or faulty PCV valve may result in an incorrect idle speed.

 

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DTC 41:
IGNITION ELECTRONIC SPARK TIMING (EST) CIRCUIT FAULT

First, understand that the EST output circuitry in the PCM issues EST output pulses (circuit 423) anytime crankshaft reference input signal pulses (circuit 430) are being received. When the ignition system is operating in the "bypass mode" (no voltage on bypass control circuit 424), the ignition module earths the EST pulses coming from the PCM. The PCM expects to see no pulses on the EST circuit during this condition. If it sees pulses (open circuit 423), the PCM sets DTC 41 and will not go into the "EST mode" (PCM will not apply 5 volts on the bypass control circuit 424).

When "EST run" RPM is reached (450 RPM) the PCM applies 5 volts to the bypass control circuit, and the EST pulses should no longer be earthed by the ignition module. At this time, the PCM should recognise the EST pulses.
If bypass control circuit 424 is shorted to 5 volts, the ignition module will always be switched to EST mode. In this case, the EST pulses will stay high and DTC 41 will be set.
If EST circuit 423 is open or shorted to 5 volts, the ignition module will switch to the EST mode when the PCM applies 5 volts to the bypass control circuit. Because the 423 circuit is open, no EST pulses will reach the ignition module, and the engine may stall. A DTC 41 may be set. The engine can be restarted, but the ignition system will operate in the bypass mode until the fault is corrected. When the engine speed goes above 1600 RPM, DTC 42 will be set. When operating may the bypass mode, the ignition module gives only 10 fixed, non-changing spark advance, which will cause a loss of engine performance.

Test Description: Number(s) below refer to the step(s) on the diagnostic chart.
2.DTC 41 can determine if the EST output signal is open or shorted. DTC 41 will set when the EST output is open if:
Engine is cranking.
Bypass control signal is at 0 volts and EST output signal is not earthed. OR Engine is running above 1600 RPM.
Bypass control signal is now at 0 volts and EST output signals were being sent.
DTC 41 will set when the EST output is shorted if:
Engine is running.
The PCM does not see EST output voltage high and then the bypass control goes from 5 volts to 0 volt. OR Engine is running above 1600 RPM.
The PCM does not see EST output voltage high but the bypass control is still at 5 volts.

DTC 42:
IGNITION BYPASS CIRCUIT FAULT

DTC 42 can determine if the bypass control signal is open or shorted.
DTC 42 will set when the bypass control is shorted low if:
Engine is running.
EST output signal was working but now bypass control voltage is 0 volts.
OR
Engine is running above 1600 RPM.
Bypass control voltage is 0 volts.
OR
DTC will set when the bypass control is open if:
Engine is running.
The PCM sent 5 volts out to the ignition module but the EST output has not been unearthed by the ignition module.
OR
Engine running above 1600 RPM.
Bypass control signal is 0 volts.
For more detailed information regarding the EST system, including DTC 42, refer Section 6C2-1, GENERAL INFORMATION in this Volume.

Test Description: Number(s) below refer to step(s) on the diagnostic chart.
2. Confirms DTC 42 and that the fault is present.
3. Checks for a normal EST earth path through the ignition module. An EST circuit 423 shorted to earth will also read less than 500 ohms; however, this will be checked later.
5. As the test light voltage touches circuit 424, the ignition module should switch, causing the digital ohmmeter to overrange (will display "OL" or "1." if the meter is in the 1,000-2,000 ohms position). Selecting the 10-20,000 ohms position will indicate above 5,000 ohms. The important thing is that the module "switched".
6. The ignition module did not switch and this step checks for:
EST circuit 423 shorted to earth.
Bypass circuit 424 open.
Faulty ignition module connection or module.
15. Checks whether the DTC 42 is a faulty PCM or an intermittent in circuits 423 or 424.

DTC 43:
KNOCK SENSOR CIRCUIT FAULT

The Electronic Spark Control (ESC) input is used to detect engine detonation. The PCM will reduce the Electronic Spark Timing (EST) advance based on the signal being received from the detonation sensor. This input allows the EST spark advance to be optimised under all conditions, then allows the "knock" input to reduce the total advance when detonation is detected. Total EST advance can be retarded by as much as 12 degrees by the knock sensor input. This could be described as a "closed-loop" spark advance system.

A loss of this signal (due to a defective sensor or circuit 815 being open or shorted to earth) would cause the EST advance to remain at a "no detonation" level. However, if detonation were occurring, the advance would not be retarded, and detonation could become severe enough under heavy engine load conditions to result in pre-ignition and potential engine damage.
The circuitry within the sensor does 2 things.
1. An internal resistor causes the 5 volts DC output from the PCM to be lowered to about 2.5 volts. This portion of the sensor is for diagnostic purposes.
2. The sensor produces a small AC voltage which goes above and below the DC voltage supplied from the PCM.
The sensor's AC voltage output is dependent upon the level of detonation or "knock". This portion of the sensor reacts like a microphone, producing a small signal voltage based on vibration.
DTC 43 will set if:
DC voltage at PCM terminal "D5" is less than 0.2 volts, or more than 4.5 volts, for more than 6 seconds.

Test Description: Number(s) below refer to step(s) on the diagnostic chart.
2. This step determines if conditions for DTC 43 still exist (voltage on circuit 815 above 4.4 volts or below 0.2 volt)
4. The PCM has a 5 volt pull up resistor which applies 5 volts to circuit 815. The 5 volts signal should be present at the knock sensor terminal during these test conditions.
5. This step determines if the knock sensor shunt resistance is 3,900 ohms (+)(-) 15 %. If the resistance is between 3,300 to 4,500 ohms, the sensor is OK.

Diagnostic Aids:
If circuit 815 is not open or shorted to earth and the voltage reading is below 4 volts, the most likely cause is an open circuit in the PCM. It is possible that a faulty PROM could be drawing the 5 volts signal down and it should be replaced, if a replacement PCM did not correct the problem.

DTC 44:
RIGHT HAND (RH) LEAN EXHAUST INDICATION

The PCM supplies a voltage of about 450 millivolts between terminal "D14" and "D13". The Oxygen (O2) sensor varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 100 millivolts, if exhaust is lean.
The sensor is like an open circuit and produces no voltage when it is below about 360 degrees C. An open sensor circuit or cold sensor causes "Open Loop" operation.

Test Description: Number(s) below refer to step(s) on the diagnostic chart.
2. DTC 44 is set when the O2 sensor signal voltage on circuit 412:
Remains below 200 millivolts for 46 seconds, and
The system is operating in "Closed Loop", and
IAT sensor signal is below 75 degrees C.
4. The DTC 44 or lean exhaust is most likely caused by one of the following:
O2 Sensor Wire - Sensor pigtail may be mispositioned and contacting the exhaust manifold.
Check for intermittent earth in wire between connector and sensor.
MAF Sensor - A shifted MAF sensor could cause the fuel system to go lean.
Lean Injector(s) - Perform power balance test using the Tech 1 "Scan" tool.
Fuel Contamination - Water, even in small amounts, near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean exhaust and can set a DTC 44 and/or DTC 64.
Fuel Pressure - System will go lean if pressure is too low. It may be necessary to monitor fuel pressure while driving the vehicle at various road speeds and/or loads to confirm.
Exhaust Leaks - If there is an exhaust leak, the engine can cause outside air to be pulled into the exhaust and past the sensor. Vacuum or crankcase leaks can cause a lean condition.

If all the above are OK, it is a faulty O2 sensor.

DTC 45:
RICH EXHAUST INDICATION

The PCM supplies a voltage of about 450 millivolts between terminal "C14" and "C13". The Oxygen (O2) sensor varies the voltage within a range of about 1 volt, if the exhaust is rich and down through about 100 millivolts if exhaust is lean.
The sensor produces no voltage when it is below about 360 degrees C. An open sensor circuit or cold sensor causes "Open Loop" operation.

Test Description: Number(s) below refer to Step number(s) on the diagnostic chart.
1. DTC 45 is set when the O2 sensor signal voltage on circuit 412.
Remains above 746 millivolts for 30 seconds; and in "Closed Loop".
Engine time after start is one minute or more.
Throttle angle between 2% - 15%.
IAT sensor signal below 95 degrees C.
4. A DTC 45 will most likely not be caused by a faulty O2 sensor. DTC 45 indicates a rich exhaust and diagnosis should begin with the items listed:
Fuel Pressure. System will be rich, if pressure is too high. The PCM can compensate for some increase. However, if pressure it gets too high, a DTC 45 may be set.
Rich Injector.
Leaking Injector.
Check for fuel contaminate oil.
Short to voltage on circuit 412.
HEI Shielding. An open earth circuit 453 (ignition system) may result in EMI, or induced electrical "noise" as reference pulses. The additional pulses result in a higher than actual engine speed signal. The PCM than delivers too much fuel, causing system to go rich. Engine tachometer will also show higher than actual engine speed, which can help in diagnosing this problem.
Canister Purge. Check for fuel saturation. If full of fuel, check canister control and hoses.
MAP Sensor. A shifted "High" MAP sensor could cause the fuel system to go rich.
Check for leaking fuel pressure regulator diaphragm by checking vacuum line to regulator for fuel.
TP Sensor. An intermittent TP sensor output will cause the system to go rich, due to a false indication of the engine accelerating.

DTC 46:
NO REFERENCE PULSES WHILE CRANKING

This DTC is intended to help in diagnosing a no-start condition. Any time the distributor is turning, the ignition module should generate the crankshaft reference pulses that the PCM should be receiving. Fuel injection pulses are "timed" from the crankshaft pulses, and without them no injection pulses will occur. The PCM can determine when these crankshaft pulses should be present, but aren't.
As with any engine while being cranked, there is a small amount of intake manifold vacuum. Also while cranking, the battery voltage will be less than 11 volts. If the PCM's MAP sensor input detects manifold vacuum and the ignition voltage input detects less than 11 volts and there are no distributor reference input pulses, a DTC 46 will set.

NOTE: It is possible for the ignition system to provide spark, yet there may not be any distributor reference pulses at the PCM.

DTC 46 will set if all the following conditions are present for more than 2 seconds:
Voltage at PCM ignition voltage input terminal "C1" is below 1 volts, and
Map sensor input detects at least 3 kPa (approx. 1" Hg) engine vacuum, and
No distributor reference input pulses at PCM terminal "D14".

Test Description: Number(s) below refer to the step(s) on the diagnostic chart.
2. If engine starts, the problem is not present now. While the PCM monitors 3 inputs to determine DTC 46, only a lack of distributor reference input signal pulses can set the DTC. If a problem occurred on the MAP or ignition voltage inputs, other problems would be apparent.
NOTE: Even one crankshaft reference pulse while cranking will cause DTC 46 to NOT set.
3. Spark on both wires proves the distributor Hall switch and ignition coil to be OK.
No spark on either lead means the ignition system is suspect of causing the DTC 46. If the ignition system cannot generate any spark, it cannot generate the distributor reference signal either.
4. The voltage should be either "OFF" (less than 1 volt) or "ON" (more than 3 volts). This is the square-wave, digital "ON-OFF" distributor reference signal generated by the ignition module. The voltage could be either reading, depending on where the distributor stopped turning.
5. This is again the distributor reference signal. When the distributor is turning, the signal changes from under 1 volt to over 3 volts, back and forth, eight times per distributor revolution. Since it changes quickly, the voltmeter can indicate only an average voltage. (expected reading - approximately 2 volts.)
6. A loose connection at PCM terminal D14 could cause an intermittent voltage measurement to be seen.
NOTE: Use ST-125 spark checker or equivalent to check for adequate spark. An ST-125 requires about 25,000 volts (25 Kilovolts or 25 kV) to spark. Do not use a spark plug in open air earthed to the engine as an indication of sufficient spark. Only a few kilovolts are required to jump the gap of a spark plug outside of the engine, and that would be an inadequate test of the ignition system.

DTC 47:
18X REFERENCE SIGNAL MISSING

The 18X signal (circuit 647) is used by the PCM to improve ignition timing accuracy during crank and at engine speeds of up to 2000 RPM. The 18X signal circuit allows the use of EST mode below 400 RPM, eliminating the need to utilise bypass mode during startup, and also allows the PCM to calculate true crankshaft position in 1/6 the time that use of the crankshaft reference signal would permit.
During normal operation, the PCM uses the 18X signal to control ignition timing until the engine speed exceeds 2000 RPM, at which time the crankshaft reference signal (circuit 430) is used. When conditions for setting DTC 47 exist, the crankshaft reference signal is used by the PCM to control EST. This condition will cause bypass mode to be used for ignition timing below 400 RPM and EST ignition timing to be degraded below 2000 RPM.

DTC 47 will set if:
The engine is running.
The PCM detects 240 (80 crank revolutions) crankshaft reference pulses, and no 18X signal pulses.
The engine RPM is below 1200.
DTC 47 does not illuminate the "Check Powertrain" lamp.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
4. If a window on the harmonic balancer is interfering with the 18X Hall-Effect switch, the ignition module will earth the 18X signal. Starter may have to be bumped several times to obtain a voltage reading.
5. Voltage reading should be lower than that obtained with engine not running, indicating a pulsed reference signal.
8. Verifies that circuit 647 is not shorted to earth or open in the harness.

Diagnostic Aids:
An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation.
Check for:
Backed out connector terminals or broken down insulation in circuit 647.
If connections and harness check OK, try monitoring voltage on circuit 647 with DVM while moving the related wiring harness and connectors with the engine idling. This may help to isolate the location of the malfunction.

DTC 49:
CAM/CRANK SIGNAL INTERMITTENT

During cranking, the ignition module monitors the dual crank sensor 3X signal. The 3X signal is used to determine the correct cylinder pair to spark first. After the 3X signal has been processed by the ignition module, it sends a crankshaft reference pulse to the PCM. When the PCM receives this pulse it will command all six injectors to open for one priming shot of fuel in all cylinders. After the priming, the injectors are left "OFF" for the next six crankshaft reference pulses from the ignition module (two crankshaft revolutions). This allows each cylinder a chance to use the fuel from the priming shot. During this waiting period, a cam signal will have been received by the PCM. Now the PCM begins to operate the injectors by energising each injector based on true camshaft position. With the engine running, the PCM monitors the cam and 18X signal pulses it receives and expects to see 36 18X signal pulses for each cam pulse. If the sequence of pulses is not correct for 15 occurrences, DTC 49 will set, indicating an intermittent problem with the cam signal or 18X signal "reference" signal.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. Determines if conditions necessary to set DTC 49 exist on this ignition cycle.
3. If 5 volts are not present at PCM harness connector terminal "D3", the cam sensor may be interfacing with the magnet in the camshaft sprocket. Bumping the starter should correct this condition.
6. If a failure is induced in the 18X signal circuit, the 5 volts on the circuit should change when the faulty wiring or connection is manipulated.

DTC 51:
PROM ERROR

DTC 52:
SYSTEM VOLTAGE TOO HIGH - LONG TIME

Diagnostic Trouble Code (DTC) 52 will set when the engine is running and PCM terminal C1 voltage is greater than 16 volts for about 109 minutes.
During the time failure is present, the pressure control solenoid is turned OFF, the transmission shifts immediately to 3rd gear and TCC operation is inhibited. Additional codes may also set.

Test Description: Number(s) below refer to step(s) on the diagnostic chart.
2. Normal Battery voltage is between 9.6 and 14.5 volts.
3. Checks to see if the voltage reading is due to the generator or the PCM. With the engine running, check voltage at the battery. If the voltage is above 14.5 volts, the PCM is OK.
4. Checks to see if generator is faulty under load condition.
Diagnostic Aids:
If diagnostic trouble code 52 is set, the transmission will have no TCC, maximum line pressure and 3rd gear only.

DTC 53:
SYSTEM VOLTAGE TOO HIGH
Diagnostic Trouble Code (DTC) 53 will set when the ignition is ON and PCM terminal C1 voltage is greater than 19.5 volts for about 2 seconds.
During the time failure is present, the pressure control solenoid is turned OFF, the transmission shifts immediately to 3rd gear and TCC operation is inhibited. Additional codes may also set.

Test Description: Number(s) below refer to step(s) on the diagnostic chart.
2. Normal Battery voltage is between 9.6 and 14.5 volts.
3. Checks to see if the voltage reading is due to the generator or the PCM. With the engine running, check voltage at the battery. If the voltage is above 14.5 volts, the PCM is OK.
4. Checks to see if generator is faulty under load condition. If the voltage is above 14.5 volts, refer to Section 6D2-1, CHARGING SYSTEM - V8 ENGINE in Volume 3 of the VR Series Service Manual.

Note on Intermittents:
Charging battery with a battery and jump-starting engine, may set Diagnostic Trouble Code 53. If Diagnostic Trouble Code sets when an accessory is operated, check for poor connections or excessive current draw.
Diagnostic Aids:
If diagnostic trouble code 53 is set, the transmission will have no TCC, maximum line pressure and 3rd gear only.

DTC 54:
SYSTEM VOLTAGE UNSTABLE

Diagnostic Trouble Code (DTC) 54 will set when the ignition is "ON" and PCM terminal "C1" voltage changed more than 3 volts in 100 milliseconds.

Test Description: Number(s) below refer to the step(s) on the diagnostic chart.
2. Diagnostic Trouble Code 54 will set if: Ignition feed voltage changes more than 3 volts in 100 milliseconds.

Diagnostic Aids:
When attempting to diagnose an intermittent problem, use the snapshot mode of the Tech 1 "Scan" tool, to review diagnostic information.

DTC 55:
PCM ANALOG - DIGITAL (a/d) CONVERSION error

Replace PCM.

DTC 56:
RUNNING LEAN UNDER LOAD

The PCM's internal circuitry can identify if the vehicle's fuel system is capable of supplying adequate amounts of fuel during heavy acceleration (power enrichment) by monitoring the voltage of the oxygen sensor. When a "power enrichment" mode of operation is requested during "Closed Loop" (remember the PCM will go "Open Loop" not make fueling changes based on oxygen sensor signal under heavy acceleration), the PCM will provide more fuel to the engine. Under these conditions, the PCM should detect a "rich" condition, high oxygen sensor voltage. If this "rich" exhaust is NOT detected at this time, a DTC 56 will set. A plugged fuel filter or restricted fuel line can prevent adequate amounts of fuel from being supplied during power enrichment mode but may be fine at idle or light acceleration.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
3. DTC 56 will set if:
The engine has been operating longer than two minutes and the PCM detects low oxygen sensor voltage for 10 seconds during "power enrichment" modes of operation.
Wrap a shop towel around the fuel pressure connector to absorb any small amount of fuel leakage that may occur when installing the gauge. Ignition "ON," pump pressure should be 235-320 kPa. This pressure is controlled by spring pressure within the fuel pressure regular assembly. Pressure below 235 kPa. may cause a lean condition and may set a DTC 44. It could also cause hard starting cold and poor driveability. Low enough pressure will cause the engine not to run at all. Restricted flow may allow the engine to run at idle, or low speeds, but may cause a surge and stall when more fuel is required, as when accelerating or driving at high speeds. Low fuel pressure under heavy acceleration conditions may set a DTC 56.
5. Restricting the fuel return line allows the fuel pressure to build above regulated pressure. With a Tech 1 "Scan" tool enable the fuel pump, pressure should rise above 325 kPa as the return line is partially closed.
12. A vehicle driven in extremely hot temperatures and a near empty fuel tank can cause the temperature of the fuel in the tank to become heated. Couple this with the fact fuel is being sent to an even hotter engine and the fuel becomes even hotter. Not all fuel sent to the engine is injected and this hot fuel is sent back to the fuel tank, increasing the temperature of the fuel in the tank even more. If temperature becomes great enough, a possible vapour leak could exist causing a DTC 56. Check that the engine cooling system and ignition timing are working properly. Adding fuel to the fuel tank could lower fuel tank temperature.

Diagnostic Aids:
A restricted filter can supply adequate amounts of fuel at idle but may not be able to supply enough fuel during heavy acceleration. A vapour lock condition can cause a DTC 56.
A known false DTC 56 can be set if the vehicle has been idling for a long period of time in high temperatures and the driver commands heavy accelerating. The reason for this is that the canister purge system causes the fuel system to go lean and the system can not respond quick enough when WOT is commanded.

 

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DTC 57:
Injector voltage monitor fault

The injector voltage monitor line is used so that the PCM will know the exact voltage the fuel injectors are operating at. This voltage is used to control the pulse width modulation of the fuel injectors. If the injector voltage monitor line drops more than 2.5 volts for more than 5 seconds, Diagnostic Trouble Code (DTC) 57 will set. This DTC will turn "ON" the "Check Powertrain" lamp, and will have a DTC set in the PCM memory that can be read with the Tech 1 "Scan" tool and can be displayed by flashing out codes.

Test Description: Number(s) below refer to step(s) on the diagnostic chart.
2.The injector voltage monitor line voltage drops more than 2.5 volt in 5 seconds.

Diagnostic Aids:
When the injector voltage monitor line voltage drops more than 2.5 volts, the PCM will operate on an incorrected value for 5 seconds until the DTC 57 is set. After the DTC 57 is set, the PCM will use the battery feed as the voltage value to control the fuel injectors base pulse width. Check PCM terminal connections for proper mating.

DTC 58:
TRANSMISSION FLUID TEMPERATURE (TFT) (SIGNAL VOLTAGE LOW)

The Transmission Fluid Temperature (TFT) sensor is a thermistor that controls the signal voltage to the PCM. The PCM applies about 5 volts on circuit 1227 to the sensor. When the transmission fluid is cold, the sensor (thermistor) resistance is high, therefore, the PCM will see high signal voltage.
As the transmission fluid temperature warms, the sensor thermistor resistance becomes less and the PCM sees a lower signal voltage at normal transmission operating temperature (approximately 82-94 degrees C). The voltage will measure about 2.0 to 1.5 volts.

Test Description: Number(s) below refer to circled step(s) on the diagnostic chart.

3. Diagnostic Trouble Code 58 will set if:
TFT sensor signal voltage indicates a transmission fluid temperature above 150 degrees C for 1 second.
4. This test will determine if circuit 1227 is shorted to earth which will cause the conditions for Diagnostic Trouble Code 58.
5. In this Section, CHART 2.1 will diagnosis the transmission internal wiring harness.

Diagnostic Aids:
Check harness routing for a potential short to earth in circuit 1227. Check terminals at pass-thru connector for a good connection. Tech 1 "Scan" tool displays transmission fluid temperature in degrees Celsius. After transmission is operated, the temperature should rise steadily to about 82-94 C then stabilise.
The "Temperature to Resistance Value" scale may be used to test the transmission fluid temperature sensor at the various temperature levels to evaluate the possibility of a "slewed" (mis-scaled) sensor. A "slewed" sensor could result in delayed garage shifts or TCC enabled complaints.

DTC 59:
TRANSMISSION FLUID TEMPERATURE (TFT) (SIGNAL VOLTAGE HIGH)

The Transmission Fluid Temperature (TFT) sensor is a thermistor that controls the signal voltage to the PCM. The PCM applies about 5 volts on circuit 1227 to the sensor. When the transmission fluid is cold, the sensor resistance is high, therefore, the PCM will see high signal voltage.
As the transmission fluid warms, the sensor (thermistor) resistance becomes less and the PCM sees a lower signal voltage. At normal transmission operating temperature (approximately 82-94 degrees C), the voltage will measure about 2.0 to 1.5 volts.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.

2. Diagnostic Trouble Code 59 will set if:
TFT sensor signal voltage indicates a transmission fluid temperature below - 37 degrees C for 1 second.
3. This test simulates a Diagnostic Trouble Code 58. If the PCM recognises the low signal 0 voltage (high temperature), and the Tech 1 "Scan" tool reads 130 degrees C or above, the PCM and wiring are OK.
4. This test will determine if circuit 1227 is open. There should be open circuit voltage of 5 volts present at the transmission fluid temperature sensor harness connector if measured with a DVM. By jumpering this 5 volt signal to earth, the PCM should recognise this change.

Diagnostic Aids:
Tech 1 "Scan" tool displays transmission fluid temperature in degrees Celsius. After transmission is operated, the temperature should rise steadily to about 82-94 degrees C then stabilise.
A faulty connection, or an open in earth circuit or circuit 1227 will result in a Diagnostic Trouble Code 59.
If DTC 15 and DTC 21 are also set, check the earth circuit for a faulty wiring or connections. Check transmission pass-thru connections.
The "Temperature to Resistance Value" scale may be used to test the transmission fluid temperature sensor at various temperature levels to evaluate the possibility of a "slewed" (mis-scaled) sensor. A "slewed" sensor could result in firm garage shifts, or TCC enabled complaint.

DTC 66:
3-2 CONTROL SOLENOID OR QDM 2 CIRCUIT FAULT
The 3-2 control solenoid is pulse width modulated to improve the 3-2 downshift by coordinating the apply rate of the 2-4 band with the release of hydraulic oil from the 3-4 clutch during a 3-2 downshift.
The PCM continually monitors the 3-2 control solenoid circuit for either a low or a high voltage depending on the commanded state of the circuit. When the transmission is in 1st gear the duty cycle of the solenoid is normally about 0%. When the transmission is in 2nd gear or higher, the duty cycle of the solenoid will be about 90%. When the transmission downshifts, 3-2/4-2/3-1, the duty cycle of the solenoid may be low.

For example: If the PCM commands the solenoid "ON," (90%) the voltage on that circuit should drop (approximately 0 volt) when the 3-2 control solenoid is earthed, if voltage stays up high (approximately 12 volts) for a period of time a DTC 66 will set.
If the 3-2 control solenoid is "OFF," (0%) the voltage on the circuit should remain high if the voltage drops (approximately 0 volt) for some time, than DTC 66 will set. The 3-2 control solenoid feedback line and the quad-driver 2 fault line must both detect on inappropriate voltage status on the line for 4 seconds to set DTC 66.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. Diagnostic Trouble Code 66 will set if:
A commanded high duty cycle (about 90%), the 3-2 control solenoid circuit voltage is high (about 12 volts).
OR
A commanded low duty cycle (about 10%), the 3-2 control solenoid circuit voltage is low (about 0 volts).
Both conditions must be present for 4 seconds.
3. The first portion of the test checks for a shorted transmission internal harness or 3-2 control solenoid.
4. The second test verifies power supply to the 3-2 control solenoid.
5. This step checks circuit 897 for a short to earth. If circuit 897 is shorted to earth the 2-4 band would be slow to apply.
6. This test checks for a short to voltage on circuit 897.
7. The final test verifies that circuit 897 is not open.

Diagnostic Aids:
Be sure to check all connections especially those at the transmission pass-thru connector.
When DTC 66 is set, the transmission will have a soft landing into 3rd gear then stay in 3rd gear only and line pressure will be high. The 3-2 control solenoid resistance should be between 9-14 ohms at 20 degrees C. The 3-2 control solenoid operates at a 50 Hertz duty cycle frequency.

DTC 67:
TORQUE CONVERTER CLUTCH "ON-OFF" solenoid or qdm 2 CIRCUIT FAULT

The Torque Converter Clutch (TCC) "ON-OFF" solenoid is a normally open exhaust valve. The PCM activates the solenoid by earthing circuit 422 with an internal quad-driver. When the solenoid is energised it blocks the fluid from exhausting the TCC circuit and the TCC is applied.
The PCM continually monitors voltage on the TCC circuit connected to the "quad driver" for either low or high voltage depending on the commanded state of the torque converter clutch. Diagnostic Trouble Code (DTC) 67 will set if there is a fault detected on the TCC solenoid circuit. For example, if the TCC were "OFF," but voltage on the TCC circuit drops as if the solenoid were applied, then DTC 67 will be set. If the TCC were "ON" but voltage on the TCC circuit remains high (about 12 volts), as if TCC solenoid were not applied, then DTC 67 will be set.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. Diagnostic Trouble Code 67 will set if:
TCC signal circuit 422 is open or shorted to earth for 2 seconds.
This test checks to identify if the TCC circuit is currently open or shorted to earth.
3. This test checks for a short to voltage on circuit 422.
4. This test checks for resistance in the TCC solenoid and internal transmission harness.
5. This test checks for power to the Torque Converter Clutch (TCC) solenoid.
6. This test verifies that circuit 422 is not shorted to earth.
7. This test verifies that circuit 422 is not open.

Diagnostic Aids:
Be sure to check all connections especially those at the transmission pass-thru connector.
TCC solenoid resistance should be 20-40 ohms minimum when measured at 20 degrees C. Maximum solenoid current flow should not exceed 1.5 amps.
DTC 67 will only find an electrical fault with the torque converter clutch. DTC 69 will diagnosis mechanical faults with the torque converter clutch. Some slight TCC slip is normal. When diagnostic trouble Code 67 is set, the transmission will have no TCC and no 4th gear, if in the hot mode.

DTC 68:
TRANSMISSION COMPONENT SLIPPING

Diagnostic Trouble Code 68 is used to determine that a component in the transmission is slipping. The PCM monitors the difference of engine RPM and output shaft RPM, with the transmission in 4th gear and TCC engaged. When the TCC is engaged the engine and transmission should be coupled together nearly 100%. This difference is displayed on the Tech 1 "Scan" tool as "Trans Slip Speed" and should be near 0 RPM. Diagnostic Trouble Code 68 will set when this value is greater than +200 RPM, meaning that something is slipping either: 2-4 band, 3-4 clutch, torque converter clutch, or forward clutch.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
4. DTC 68 will set if:
Throttle position 0%-50%.
TFT between 20 degrees C-115 degrees C.
TCC is enabled.
3rd or 4th gear is selected or indicated.
Trans slip speed is greater than 200 RPM for 10 seconds.
NOTE: This checking procedure is a two person operation, one to drive the vehicle, the other to operate the Tech 1 'Scan" tool and record the various parameters. This test must only be conducted where it is legally permitted to drive at high speed and in a safe manner.
The jumper switch is a two position switch fitted with suitable length wires and terminals to enable connection to PCM terminals "A9" and "C2".
This test must be performed by slightly accelerating under light to moderate throttle, with throttle position less than 60% while monitoring the "Trans Slip Speed".
Even with the TCC engaged some slight slipping is considered normal. During this test it is possible to see negative RPM numbers, this is a normal condition, the important item to look for is that "Trans Slip Speed" does not exceed +200 RPM value.
5. This test checks for a faulty 2-4 band.
7. This test checks for a faulty 3-4 clutch assembly or TCC.
10. This test will identify a faulty forward clutch that may not have been identified in the previous, test because the overrun clutch is applied in the manual positions.

Diagnostic Aids:
Diagnostic Trouble Code 68 can be set falsely by having either an intermittent connection at the PCM or vehicle speed sensor, or electro motive induction on the vehicle speed sensor or engine reference signal which will cause a false signal and therefore, a false code. Make sure the vehicle speed sensor wires and engine reference signal wire are not routed near high voltage sources such as spark plug cables.
If both DTC 68 and DTC 82 are set, then the 1-2 shift solenoid circuit became open in 4th gear.

DTC 68 may be set if the transmission main line pressure is too low, refer to Section 7C3 in Volume 4 of this Service Manual for the proper testing procedure.
DTC 68 may be set if the vehicle was/is being used to tow something beyond its rated towing capacity, or in the wrong gear position. The correct gear for towing is "3".
If the transmission is slipping, remove the valve body and check to see if the valve body gaskets are blocking any oil passages. If OK, remove the servo and check out the seals and spring before tear down.

DTC 69:
TORQUE CONVERTER CLUTCH (TCC) STUCK "ON"

Diagnostic Trouble Code 69 is for determining a mechanical fault which will cause the Torque Converter Clutch to be stuck "ON." An electrical fault in the torque converter clutch solenoid circuit which could cause the torque converter clutch to be "Stuck ON" is diagnosed in DTC 67.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. Diagnostic Trouble Code (DTC) 69 will set if:
Gear selector in a drive range transmission in 2nd, 3rd or 4th gear.
TCC commanded "OFF".
TP sensor signal greater than 25%.
TCC slip is between -20 and +20 RPM.
All conditions must be met for 4 seconds.
3. The torque converter clutch solenoid is normally open. When the PCM energises the solenoid its blocks fluid from passing through it which causes the pressure in the circuit to rise and apply the torque converter clutch in the torque converter.

Diagnostic Aids:
When Diagnostic Trouble Code 69 is set, the transmission will have TCC "ON" in all gears and have early shifts.
An internally damaged torque converter may cause DTC 69 to be set.
If the converter clutch signal valve is stuck "ON," the customer should not complain about a symptom.

DTC 72:
VEHICLE SPEED SIGNAL INTERMITTENT

The Vehicle Speed Sensor (VSS) circuit consists of a magnetic induction type sensor and vehicle speed sensor wiring. Gear teeth pressed on the output shaft of the transmission induce an alternating current in the vehicle speed sensor. This alternating current is transmitted to the PCM.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. Diagnostic Trouble Code 72 will set if:
Two successive speed readings have a difference of more than 1000 RPM in any drive range (difference must be more than 2048 RPM in park or neutral).
This test checks the vehicle speed sensor signal to the PCM.
3. This test checks the vehicle speed sensor signal to the powertrain control module.

Diagnostic Aids:
DTC 72 is used to detect an intermittent failure. If a hard VSS fault exists, it will set DTC 24.
DTC 72 will set if the vehicle is operating at a road speed and something happens to the VSS signal.
Check all connections for proper retention. When Diagnostic Trouble Code 72 is set, the transmission will have high line pressure and 3rd gear only. If DTC 72 is set while in 4th gear, the vehicle will stay in 4th gear. However, as the vehicle is coasting to stop the transmission will downshift normally from 4 to 3. Once the downshift into 3rd gear has occurred, the vehicle will stay in 3rd gear.

Check that wiring harness for VSS are not routed near high voltage sources such as spark plug cables which could induce a false signal onto the VSS signal.
DTC 72 could possibly be set by rapidly accelerating the vehicle in a loose material (such as sand or gravel) where the wheels can be spinning faster than actual vehicle speed then having the spinning wheel rapidly decrease when it contacts a hard surface. Review DTC history to identify when DTC 72 was set.

DTC 73:
PRESSURE CONTROL SOLENOID (CURRENT ERROR)

The pressure control solenoid is a PCM controlled device used to regulate transmission fluid line pressure. The PCM looks at TP sensor voltage, engine RPM and other inputs to determine the line pressure appropriate for a given load, then regulates the pressure by applying a varying amperage to the pressure control solenoid. The applied amperage can vary from 0.1 to 1.1 amp. The PCM then monitors the amperage at the pressure control solenoid low line and if the low line amperage varies more than 0.16 amp from the commanded amperage for a duration of about 1 second, Diagnostic Trouble Code (DTC) 73 is set. Once DTC 73 is set, the pressure control solenoid is disabled and full line pressure will be applied until the next time the ignition key is cycled. If upon restart, the current error does not exist, DTC 73 will remain stored but the pressure control solenoid will resume normal function.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. This procedure verifies an amperage difference of more than 0.16 amp between the actual pressure control solenoid current and the desired pressure control solenoid current, the PCM's ability to control amperage to the pressure control solenoid.
3. This part of the test checks the pressure control solenoid for internal shorts and integrity.

Diagnostic Aids:
Check for poor connections at PCM and especially at the transmission pass-thru connector.
Pressure control solenoid resistance should be between 3.5-8.0 ohms at 20 degrees C.
When Diagnostic Trouble Code 73 is set, the transmission will have harsh shifts and maximum line pressure.
The PCM controls the pressure control solenoid by commanding current between 0 and 1.1 amps. 1.1 amps corresponds to minimum line pressure, and 0 amps is maximum line pressure (if solenoid loses power, transmission will still have maximum line pressure).

DTC 75:
SYSTEM VOLTAGE LOW

Diagnostic Trouble Code (DTC) 75 will set when the ignition is "ON" and PCM terminal "C1" voltage is less than 8.6 volts for about 4 seconds. Minimum voltage allowed for Diagnostic Trouble Code 75 to set is on a graduated scale and will change with temperature. Minimum voltage at - 40 degrees C is 7.3 volts, minimum voltage at 152 degrees C is 11.4 volts, 8.6 volts is the minimum voltage at 90 degrees C.
During the time the failure is present: the pressure control solenoid is turned "OFF," maintaining 3rd gear only, and inhibiting 4th gear and TCC operation and line pressure will be at its maximum.

Test Description: Number(s) below refer to step(s) on the diagnostic chart.
2. Normal battery voltage is between 9.6 - 14.5 volts.
3. Checks to see if the low voltage reading is due to the generator, circuit 39 or PCM, with engine running check voltage at the battery. If the voltage is below 8.6 volts, the PCM is OK.

Diagnostic Aids:
If Diagnostic Trouble Code 75 sets when an accessory is operated, check for poor connections or excessive current draw.
When Diagnostic Trouble Code 75 is set, the transmission will have no TCC, high line pressure and third gear only.

DTC 79:
TRANSMISSION FLUID TEMPERATURE TOO HIGH

The Transmission Fluid Temperature (TFT) sensor is a thermistor within the (PSA), that controls the signal voltage to the PCM. The PCM applies about 5 volts on circuit 1227 to the sensor. When the transmission fluid is cold, the sensor (thermistor) resistance is high, therefore, the PCM will sense high signal voltage about 4-4.5 volts.
As the transmission fluid temperature warms (normal transmission operating temperature 82 degrees C - 94 degrees C), the sensor (thermistor) resistance becomes less and the voltage will measure about 2.0 to 1.5 volts. If the fluid temperature becomes greater than 146 degrees C for 30 minutes, a DTC 79 will set.

When DTC 79 sets, the fluid may have been severely degraded and the PCM will shift the transmission into 3rd gear and apply the torque converter clutch to reduce the build up of heat in the transmission.

Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
1. DTC 79 will set if:
TFT signal voltage indicates a transmission fluid temperature above 146 degrees C for 30 minutes.
4. The fluid must be replaced because the extreme temperature has broken down the additives in the fluid needed to properly protect the transmission. Continued use of this fluid will lead to premature failure of the transmission.
5. If the cooling system is operating as design intent there is nothing you as a technician can do except inform the customer of these limitations.

Diagnostic Aids:
Brake torquing the transmission to check for a bad converter or engine miss under load may cause DTC 79 to set. Review DTC history to determine what conditions DTC 79 was set.
Check harness routing for a potential short to earth in circuit 1227.
Tech 1 "Scan" tool displays TFT temperature while transmission is operating, the temperature should rise steadily to about 82 degrees C-94 degrees C then stabilise.
The temperature to resistance value table, may be used to test the transmission fluid temperature sensor at the various temperature levels to evaluate the possibility of a "skewed" (mis-scaled) sensor. A "skewed" sensor could result in delayed garage shifts or TCC enabled complaints.

 

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DTC 81:
2-3 SHIFT SOLENOID "B" CIRCUIT FAULT

The PCM continually monitors voltage on each circuit connected to the "quad driver" module looking for either low or high voltage depending on the commanded state of the devices connected to it. Diagnostic Trouble Code 81 will set if there is a fault detected on the 2-3 shift solenoid "B" circuit. For example, if 2-3 shift solenoid "B" is commanded "ON" by the PCM, then voltage on that circuit should drop when the solenoid is earthed, if the voltage remains high for at least 2 seconds after the "ON" command is given, then Diagnostic Trouble Code 81 will be set. The opposite is also true if 2-3 shift solenoid "B" is "OFF" then the voltage on the circuit should remain high, if voltage drops for more than 2 seconds, then Diagnostic Trouble Code 81 will be set.
Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. This test checks the PCM's ability to provide a earth for control of 2-3 shift solenoid "B".
3. This procedure checks 2-3 shift solenoid "B" and the transmission internal wiring harness for shorts.
4. This test checks for power to the 2-3 shift solenoid "B" from the ignition through the Fuse F12.
5. This test verifies that circuit 1223 is not shorted to earth.
6. The final test verifies that circuit 1223 is not open.

Diagnostic Aids:
Check all connections especially those at the transmission pass-thru connector. 2-3 shift solenoid "B" resistance should measure 20-40 ohms minimum when measured at 20 degrees C.
2-3 shift solenoid "B" current flow should not exceed 0.75 amps.
The shift solenoid should energise at a voltage of 7.5 volts or more (measured across the terminals). The shift solenoid should de-energise when voltage is one volt or less.
When Diagnostic Trouble Code 81 is set, the transmission will have no TCC, high line pressure and second or third gear only depending upon when the fault occurred.

If both solenoids lose power, third gear only will result, unless manual 2nd gear is selected.

DTC 82:
1-2 SHIFT SOLENOID "A" CIRCUIT FAULT

The PCM continually monitors voltage on each circuit connected to the "quad driver" module looking for either low or high voltage depending on the commanded state of the devices connected to it. Diagnostic Trouble Code 82 will set if there is a fault detected on the 1-2 shift solenoid "A" circuit. For example, if 1-2 shift solenoid "A" is commanded "ON" by the PCM, then voltage on that circuit should drop when the solenoid is earthed, if the voltage remains high for at least 2 seconds after the "ON" command is given, then Diagnostic Trouble Code 82 will be set. The opposite is also true if 1-2 shift solenoid "A" is "OFF" then the voltage on the circuit should remain high, if voltage drops for more than 2 seconds, then Diagnostic Trouble Code 82 will be set.
Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. This test checks the PCM's ability to provide a earth for control of 1-2 shift solenoid "A".
3. This procedure checks 1-2 shift solenoid "A" and the transmission internal wiring harness for shorts.
4. This test checks for power to the 1-2 shift solenoid "A" from the ignition through the Fuse F12.
5. This test verifies that circuit 1222 is not shorted to earth.
6. The final test verifies that circuit 1222 is not open.

Diagnostic Aids:
Check all connections especially those at the transmission pass-thru connector. 1-2 shift solenoid "A" resistance should measure 20-40 ohms minimum when measured at 20 degrees C.
1-2 shift solenoid "A" current flow should not exceed 0.75 amps.
The shift solenoid should energise at a voltage of 7.5 volts or more (measured across the terminals). The shift solenoid should de-energise when voltage is one volt or less.
When Diagnostic Trouble Code 82 is set, the transmission will have no TCC, high line pressure and second or third gear only depending upon when the fault occurred.

If both solenoids lose power, third gear only will result, unless manual 2nd gear is selected.

DTC 83:
TORQUE CONVERTER CLUTCH (TCC) SOLENOID "PWM" CIRCUIT FAULT

The TCC "PWM" solenoid is used in combination with the TCC "ON-OFF" solenoid to regulate fluid to the torque converter, and is attached to the control valve body within the transmission. The Powertrain Control Module (PCM) supplies a earth allowing current to flow through the solenoid coil according to the duty cycle (percentage of "ON" and "OFF" time). This current flow through the solenoid coil creates a magnetic field that magnetises the solenoid core. The magnetised core attracts the checkball to seat against spring pressure. When the checkball is seated, it essentially changes actuator feed limit (AFL) fluid to converter clutch signal (CC SIGNAL) fluid, that is directed to the base of the Isolator Valve. Depending on the PCM controlled duty cycle, the TCC PWM solenoid determines the value of the CC SIGNAL fluid pressure

By having an electronically controllable, variable fluid pressure acting on the end of the Isolator Valve, the force controlling the position of the Regulated Apply Valve can now vary the regulated apply (REG AP) fluid pressure that is directed to the Converter Clutch Valve.
The use of the Torque Converter Clutch Pulse Width Modulated, (TCC PWM) solenoid provides the ability of being able to control more precisely, the rate of Torque Converter Clutch (TCC) apply and release.

Action Taken (PCM will default to):
Inhibit TCC operation.
Inhibit 4th gear operation if in hot mode.

Test Description: Number(s) below refer to step number(s) on the diagnostic table.
2. DTC 83 will set if:
The PCM commands the solenoid "ON" and voltage remains high (B+).
or
The PCM commands the solenoid "OFF" and voltage remains low (zero volts).
All conditions met for 2 seconds.
This test will check if the PCM is commanding the TCC "PWM" solenoid "ON".
4. This test will check for voltage to the TCC "PWM" solenoid.

Diagnostic Aids:
Check all connections at the transmission pass-thru connector.
When DTC 83 is set, the PCM will inhibit TCC operation and 4th gear if in hot mode.

Under light throttle with the vehicle in gear, the TCC "PWM" solenoid will go from 0% to 90% in anticipation of apply the TCC when 3rd gear is achieved.

 

[ephect]

This should be sticky'd and locked to prevent posts like this

Great info

 

[St3alth187]

+1 to sticky