Faulty Signal. Permanent Fault

Faulty signal. Permanent fault

Checking the transmission output speed sensor signal








- Ignition off
- Check the control module and transmission output speed sensor connectors. Check for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault
- Reinstall the components, reconnect the connectors etc.
- Raise the car so that the drive wheels can rotate freely
- Engine idling
- Gear selector in position D
- Read off the transmission output speed signal.
Check that the speed increases with engine speed (RPM). If the speed is updated, the cause of the fault was loose connections in the control module or vehicle speed sensor (VSS) connectors.

Note! A diagnostic trouble code (DTC) may be stored in the ABS system when the rear wheels are stationary and the front wheels rotate. Erase any diagnostic trouble codes (DTCs) in the ABS system after completing fault-tracing.

Other information:
- To access the control module connector, see Connecting the breakout box, 4T65EV-GT Connecting the Breakout Box
- To access the transmission connector, see Connecting the breakout box, GM automatic transmissions, 4T65EV-GT Connecting the Breakout Box, GM Automatic Transmissions.





Does the speed increase with engine speed (RPM)?

Yes - FAULT FOUND

No - Checking wiring and sensors

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Checking wiring and sensors




- Ignition off.
Check the power supply cable between vehicle speed sensor (VSS) connector terminal #1 (control module side) and control module terminal #57 (#A57). Check for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Check for a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Check for a short-circuit to supply voltage according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Hint: With the control module connected and the ignition on, the voltage between speed sensor connector terminal #1 and ground (breakout box terminal #53) must be approximately 1-3 V below Ubat.

Check the signal cable between speed sensor connector terminal #2 (control module side) and control module terminal #39 (#A39). Check for an open-circuit. See Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Check for a short-circuit to ground. See Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Check for a short-circuit to supply voltage. See Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Remedy as necessary.

Other information:
- To connect the breakout box, see Connecting the breakout box, 4T65EV-GT Connecting the Breakout Box
- To replace the vehicle speed sensor (VSS), see Output speed sensor gearbox, replacing Transmission Output Speed Sensor, Replacing
- For information about signals, see Signal specification, 4T65EV-GT Signal Specification.









Was a fault detected?

Yes - Verification

No - No Fault Found

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Verification




Verification

Hint: After carrying out the repair, check that the fault has been remedied.








- Ignition off.
- Reinstall connectors, components etc.
- Raise car so that drive wheels are unimpeded.
- Start the engine and let it idle.
- Shift gear selector to position D so that the drive wheels begin to rotate.
- Read off the transmission speed.
Check that speed is updated

Note! When the rear wheels are stationary and the front wheels rotate, diagnostic trouble codes (DTCs) can be stored in the ABS system. Erase any diagnostic trouble codes (DTCs) stored in the ABS system after fault-tracing.

Note! Ensure that the wheels are not rotating when the gear selector is moved.





Was speed updated?

Yes - Verification completed

No - Fault-tracing information

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Fault-tracing information




Information

Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - Exit Fault-Tracing

No - Attempt New Test

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Attempt New Test - Checking the transmission output speed sensor signal

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