Diagnostic Procedures
- Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM.
- Install a scan tool. Turn ON the ignition with the engine OFF. Record the DTC Freeze Frame and Failure Records. Clear the DTC. Raise the drive wheels. Start the engine. Allow the engine to idle in gear. Does the scan tool display vehicle speed above 0 MPH? If yes, go to next step. If no, go to step 4.
- Turn OFF the ignition. Turn ON the ignition with the engine OFF. Review the Freeze Frame data and record the parameters. Start the engine. Operate the vehicle within the Freeze Frame conditions and Conditions for Running DTC. Does the scan tool display vehicle speed above 0 MPH? If yes, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM. If no, go to next step.
- Verify that the latest calibration is installed in the PCM. Update the PCM with the latest calibration as necessary. Did the PCM require a calibration update? If yes, go to step 14. If no, go to next step.
- Turn OFF the ignition. Disconnect the PCM. Measure the resistance between terminal C2-20 and C2-21. Is the resistance 966-2,200 ohms? If yes, go to step 7. If no, go to next step.
- Test the VSS high signal and VSS low signal circuits for the following conditions:
- An open circuit or high resistance condition
- VSS high signal and VSS low signal circuits shorted together
Did you find and correct a condition? If yes, go to step 14. If no, go to step 11.
- Measure the resistance between the terminal C2-21 and ground. Is the resistance greater than 50 K ohms? If yes, go to step 10. If no, go to next step.
- Leave the DMM connected between terminal C2-21 and ground. Disconnect the VSS. Measure the resistance between terminal C2-21 and ground. Is the resistance greater than 50 K ohms? If yes, go to step 11. If no, go to next step.
- Repair the short to ground in the VSS high signal circuit. After repairs, go to step 14.
- Connect the DMM between terminal C2-20 and C2-21. Measure the AC voltage with the DMM while rotating the drive wheels by hand. Is the AC voltage equal to or greater than 0.5 V? If yes, go to step 13. If no, go to next step.
- Remove the VSS. Inspect the VSS and the VSS rotor for the following conditions:
- VSS damage.
- VSS rotor damage.
- Excessive air gap between the VSS rotor and the VSS.
- Incorrect alignment between the VSS and the VSS rotor.
Repair or replace any of the above items as necessary. Did you find and correct a condition? If yes, go to step 14. If no, go to next step.
- Replace the VSS. After repairs, go to step 14.
- Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After repairs, go to next step.
- Using the scan tool, clear the DTCs. Start the engine. Idle at normal operating temperature. Operate the vehicle within the Conditions for Running DTC. Does the scan tool indicate that this diagnostic has run and passed? If yes, system is okay. If no, go to step 2.
WARNING:
In order to avoid damage to the drive axles, support the lower control arms in the normal horizontal position. Do not run the vehicle in gear with the wheels hanging down at full travel.
NOTE:
Record the Failure Records before clearing the DTCs. Using the Clear Info function erases the Failure Records from the PCM.