Engine Control System

DTC P0500: Malfunction in VSS Circuit (M/T)
1. Test-drive the vehicle.
2. Check the vehicle speed with the scan tool. Is the correct speed indicated?
YES- Intermittent failure, system is OK at this time.
Check for poor connections or loose wires at the VSS and the ECM.
NO-Go to step 3.
3. Turn the ignition switch OFF.
4. Block the rear wheels and set the parking brake.
5. Raise the front of the vehicle, and make sure it is securely supported.
6. Turn the ignition switch ON (II).
7. Block the right front wheel, and slowly rotate the left front wheel.




8. Measure voltage between the ECM connector terminals B20 and C23.
Does the voltage pulse between 0 V and 5 V?
YES-Substitute a known-good ECM and recheck. If symptom/indication goes away, replace the original ECM.
Diagnostic Strategies

NO-Go to step 9.
9. Turn the ignition switch OFF.
10. Disconnect the ECM connector C (31P).
11. Turn the ignition switch ON (II).
12. Block the right front wheel, and slowly rotate the left front wheel.




13. Measure voltage between the ECM connector terminals B20 and C23.
Does the voltage pulse between 0 V and 5 V?
YES-Substitute a known-good ECM and recheck. If the symptom/indication goes away, replace the original ECM.
Diagnostic Strategies

NO-Check these items:
- A short or an open in the wire between the ECM (C23) and the VSS.
- If the wire is OK, lest the VSS.