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Cliff2468

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So I’ve seen a lot of post about the speedo not working at all. But the problem with my VS wagon is everything works. It just doesn’t go past 80km sometimes. It either stops or starts to go backwards. It’s clearly not the cluster since I replaced it and still have the same problem (Unless the clusters unluckily have the same problem). Will also mention that I replaced the motor and box recently. And that was when the problem started to occur. Would this just be a faulty speed sensor? The ECU is the one that was already in my car. Could that be a problem as well? If anyone’s had this problem please let me know if and how you fixed it.

Thanks
 

losh1971

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Try fitting another speed sensor since that appears to be the problem.
 

Trevor loves holden.

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From a old link by BlackVXGTS
"For Automatic Transmissions. The Vehicle Speed Sensor (VSS) for the automatic transmission is located on the transmission extension housing and is accessible from the right side of the vehicle.The vehicle speed sensor contains a coil that has continuous magnetic field. A voltage signal is induced in the vehicle speed sensor by teeth on the output shaft that rotate past the sensor and break the magnetic field. Each break in the field sends an electrical pulse to the PCM. This voltage output will vary with transmission output shaft 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 4,000 RPM in fourth gear the voltage will be approximately 25 Volts AC.The PCM uses speed information from this sensor to determine the following:
. Vehicle speed.
. Control shift points.
. Calculate transmission slip.
. Engine fueling modes.

Diagnostic Trouble Code (DTC) 24 will set if a fault exists in the vehicle speed sensor circuit while the vehicle is not moving. As the vehicle is accelerated, the PCM shifts the transmission to second gear at approximately 50 km/h. If the vehicle speed signal is still not present while in second gear, DTC 24 is set, the transmission will have maximum line pressure, 2nd gear only and have no TCC and a default value will be substituted by the PCM.

DTC 72 will set if there is an intermittent failure in the VSS circuit while the vehicle is moving. As long as the fault remains and the Diagnostic Trouble Code 72 is set, the PCM will have maximum line pressure and 3rd gear only. If the fault is removed, normal operation will resume after the next ignition cycle."

BlackVXGTS, Mar 12, 2015
 

losh1971

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I had a speed sensor issue a few years back and no fault codes were logged. However i did lose the ability to shift.
Edit, i think i paid $15 for a SH sensor. So not exi if the OP wants to try the easiest thing to replace first up.
 

Trevor loves holden.

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Not all scan tools will be able to pick up Transmission codes only engine diagnostics, I'm not saying yours wont. Replace the sensor and if it still does it then it maybe a wire issue or your PCM.
 
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