4l60e Problems and Solutions
I found this on another forum, thought it might helpful seeing as so may of us have trans
problems i'm no trans prerson so i'm sorry for any inaccuracies.
hope it helps at least one person out if not ohwell
Common failures on 4L60E, symptom -> cause -> any possible repair:
1. Slow, slipping or no reverse: “lo-reverse” clutches are worn out, fluid leak in the
reverse apply circuit, or broken sunshell. It is possible to remedy a fluid problem by
removing the checkball from its cage in the case in the rear of the trans may help (must
remove valvebody), or adding a high-viscosity additive such as Lucas Transmission
additive or other seal restorer product. May also have worn boost valve (can replace in
the pan).
2. 1-2 shift does not happen at WOT until you let off the gas: Best case: try
replacing the TPS. Middle case: leak in the 2nd gear apply circuit (servo assembly or 1-2
accumulator). Doublecheck by using the pressure gauge and watch for a big drop when
the PCM commands 2nd gear. Worst case: poor line pressure rise (see below).
3. 1-2 Shift shudder at WOT; delayed or abnormal 1-2 shift; There's a problem
ONLY on the 1-2 shift: 1-2 accumulator piston cracked or stuck cocked in the bore. Check
the yellow spring inside the accum housing for breakage. Also, if the accumulator housing
walls are scored, the housing must be replaced. Easy fix in the pan.
4. 1-2 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and
linear electrical response over the entire range of motion. If not, replace.
5. Trans does not upshift out of first, speedometer reads zero at all times: VSS
failure. Easy fix on rear of transmission, but xmember must come out to access VSS.
6. No 3rd or 4th gear: “3-4” clutches are worn out. R&R. The car is safe to drive
(in 2) until you can get it fixed.
7. Sudden grinding noise with no prior warning primarily in 2nd gear, behavior in
reverse may be abnormal; sunshell is fractured. R&R. Try not to run or drive the car or
further damage could result.
8. 1st and 3rd only, no 2,4 or R; sunshell is fractured or splines are sheared off.
R&R. Try not to run or drive the car or further damage could result.
9. No 2nd or 4th gear. 2-4 band is slipping. Servo seals may be damaged (can be
fixed without removing trans. Otherwise, 2-4 band is worn out. R&R.
10. Trans shifts into gear harshly, 3rd gear starts, manual 2nd available but no 1st,
no 4th, and no TCC lockup: No power to transmission, or trans is in limp-home mode.
Check trans fuse underhood, and make sure transmission electrical connector is plugged
in. Easy fix.
11. No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD : ShiftA
solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.
12. No 2nd or 3rd available: ShiftB solenoid failed: Easy fix in the pan. Or a wiring
problem from PCM to trans.. or PCM.
13. No TCC lockup: Brake pedal switches improperly adjusted (always on), TCC
solenoid failed (easy fix in the pan), TCC clutch worn out (must remove trans and replace
TC).
14. TCC always locked: TCC apply solenoid circuit shorted to ground, TCC solenoid
blockage (easy fix in pan), or TC broken (must remove trans and replace TC).
15. Horrible noise in 4th and feels like the brakes are on: overrun clutches are
applying due to a cracked or leaking forward piston. Overrun clutches will be worn out
after 30 seconds of this behavior. Car can be safely driven in D. R&R.
16. Soft shifting, gradual performance degradation: Poor line pressure rise due to
leaking boost valve, clogged EPC filter screen, failing EPC solenoid, or worst case: leaky
seals throughout. Transgo HD2-C kit fixes first two without removing trans. Seal restorer
may fix last problem, but probably R&R. Also try a transmission flush with BG brand
products (Firestone stocks it).
17. No forward movement in OD or D, but L2, L1 and R work: Forward sprag is
broken. R&R. Try not to run or drive the car or further damage could result.
18. Extremely harsh shifts from P or N, normal shifts at WOT: EPC (Electronic
Pressure Control) solenoid failed. Easy fix in pan. Fix as soon as possible or hard parts
will eventually break.
19. Loud bang, grinding sound, loss of all gears, and a binding driveshaft: snapped
output shaft. Try to wiggle driveshaft - if more than 0.020" play, that's the sign. R&R.
20. Trans seems noisy when moving in 1st and Reverse, noise goes away instantly
if you shift to N or the trans goes into 3rd gear: Reaction planetary is worn out due to
high miles or insufficient lubrication. Not a critical failure, but not a good sign either. R&R
sooner rather than later.
21. No movement in any gear: pump failure, or total loss of fluid. R&R, or refill pan
and find the leak. If out of fluid, avoid running the engine until the trans is refilled to avoid
pump damage. To check for pump failure, check fluid level with the engine off, then start
the engine and recheck fluid level. If level does not go down when engine is running, the
pump is broken.
22. Transmission does not shift automatically, only manually. Swap in a
known-good PCM, check wiring, check other sensors such as VSS and TPS.
23. 3rd gear starts, can manually shift through all gears. When car has been
turned off for a bit, then back on it will run normally.: VSS dropoff w/ Hi-stall converter.
The rpms are too high, but VSS is showing no movement. Happens after a tire burning
take-off. Doesn't store a code, will not throw a CEL (I've heard that it will store a code if it
happens 3 or more times). Cure: Reprogram PCM for VSS dropoff -- PCMforLess knows
about it.
24. Car feels sluggish off the line, No 1st, 4th or TCC lockup available, Manual 2nd,
3rd and Reverse are only available gears, CEL is on: Transmision is either in limp-home
mode or has lost electrical power. If there are lots of error codes in the PCM, check the
underhood fuse that powers the transmission, and if it pops again, look for a short in that
circuit like an O2 sensor harness touching exhaust. Otherwise, check PCM codes for a
particular fault in the transmission causing the PCM to put it in limp-home mode.
25. Fluid leak out of the front of trans where the converter connects; partial or full
loss of movement: Front pump bushing walked out. R&R. May have to replace converter
also if hub is scored. Note that a leaking front seal usually means the bushing is walking
out (i.e. call your local trans shop and schedule an appt.).
26. Torque converter shudder in 4th while lockup is engaged; problem goes away
when the brake pedal is pressed slightly to unlock converter. Have a shop verify line
pressure, and provided no valves in the TCC hydraulic circuit are worn, replace the torque
converter. Also, Lubegard Shudder Fix will at least fix this for awhile. Or try a
transmission flush by a shop that uses BG brand products.
27. Shift suddenly become very hard. When going from park to either reverse or drive
it slams into gear. 1-2 and 2-3 shifts are also harsh. All gears seems to work. Problem
may be intermittent: Check TPS for smooth electrical response. If the response is jumpy
or erratic at all, replace TPS.
28. All fluid pumped out through the vent tube: Plugged cooler line. Flush the
transmission cooler and cooler lines. Also could be overfiled transmission.
29. Car acts like it's in OD in neutral, car is locked stationary in R, engine feels
loaded in P, all four forward positions work fine:Internal crossleak feeding the forward
clutches all the time. Most likely a cracked input housing. R&R required. Car can safely be
driven gently in forward gears until the repair.
30. Needle bearings in the pan, first gear and/or reverse may be noisy: Either a
torrington bearing or a planetary bearing is on its way out. Trans will eventually die a
loud, catastrophic death. Cheaper to rebuild now (saves further damage to hard parts),
but requires R&R. It is drivable until it breaks.
31. 1-2 or 2-3 shift is slow/soft above part throttle: Trans is on its way out. R&R.
Operational phases
A torque converter has three stages of operation:
* Stall. The prime mover is applying power to the pump but the turbine cannot rotate. For example, in an automobile, this stage of operation would occur when the driver has placed the transmission in gear but is preventing the vehicle from moving by continuing to apply the brakes. At stall, the torque converter can produce maximum torque multiplication if sufficient input power is applied (the resulting multiplication is called the stall ratio). The stall phase actually lasts for a brief period when the load (e.g., vehicle) initially starts to move, as there will be a very large difference between pump and turbine speed.
* Acceleration. The load is accelerating but there still is a relatively large difference between pump and turbine speed. Under this condition, the converter will produce torque multiplication that is less than what could be achieved under stall conditions. The amount of multiplication will depend upon the actual difference between pump and turbine speed, as well as various other design factors.
* Coupling. The turbine has reached approximately 90 percent of the speed of the pump. Torque multiplication has essentially ceased and the torque converter is behaving in a manner similar to a plain fluid coupling. In modern automotive applications, it is usually at this stage of operation where the lock-up clutch is applied, a procedure that tends to improve fuel efficiency.
The key to the torque converter's ability to multiply torque lies in the stator. In the classic fluid coupling design, periods of high slippage cause the fluid flow returning from the turbine to the pump to oppose the direction of pump rotation, leading to a significant loss of efficiency and the generation of considerable waste heat. Under the same condition in a torque converter, the returning fluid will be redirected by the stator so that it aids the rotation of the pump, instead of impeding it. The result is that much of the energy in the returning fluid is recovered and added to the energy being applied to the pump by the prime mover. This action causes a substantial increase in the mass of fluid being directed to the turbine, producing an increase in output torque. Since the returning fluid is initially traveling in a direction opposite to pump rotation, the stator will likewise attempt to counter-rotate as it forces the fluid to change direction, an effect that is prevented by the one-way stator clutch.
Unlike the radially straight blades used in a plain fluid coupling, a torque converter's turbine and stator use angled and curved blades. The blade shape of the stator is what alters the path of the fluid, forcing it to coincide with the pump rotation. The matching curve of the turbine blades helps to correctly direct the returning fluid to the stator so the latter can do its job. The shape of the blades is important as minor variations can result in significant changes to the converter's performance.
During the stall and acceleration phases, in which torque multiplication occurs, the stator remains stationary due to the action of its one-way clutch. However, as the torque converter approaches the coupling phase, the energy and volume of the fluid returning from the turbine will gradually decrease, causing pressure on the stator to likewise decrease. Once in the coupling phase, the returning fluid will reverse direction and now rotate in the direction of the pump and turbine, an effect which will attempt to forward-rotate the stator. At this point, the stator clutch will release and the pump, turbine and stator will all (more or less) turn as a unit.
Unavoidably, some of the fluid's kinetic energy will be lost due to friction and turbulence, causing the converter to generate waste heat (dissipated in many applications by water cooling). This effect, often referred to as pumping loss, will be most pronounced at or near stall conditions. In modern designs, the blade geometry minimizes oil velocity at low pump speeds, which allows the turbine to be stalled for long periods with little danger of overheating.
Torque converter - Wikipedia, the free encyclopedia
