## PGM-FI System

#### DTC Troubleshooting (cont'd)

11-390

DTC P0500: VSS Circuit Malfunction

DTC P0501: | VSS Range/Performance Problem

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 at 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 ECM/PCM connector terminals A18 and A24.

ECM/PCM CONNECTOR A (31P)

Wire side of female terminals

Does the voltage pulse between 0 V and 5 V or battery voltage?

YES | - Substitute a known-good ECM/PCM and recheck (see page 11-313). If symptom/indication goes away, replace the original ECM/PCM.
NO | - Go to step 9.

9. Turn the ignition switch OFF.
10. Disconnect ECM/PCM connector A (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 ECM/PCM connector terminals A18 and A24.

ECM/PCM CONNECTOR A (31P)

Wire side of female terminals

Does the voltage pulse between 0 V and 5 V or battery voltage?

YES | - Substitute a known-good ECM/PCM and recheck (see page 11-313). If symptom/indication goes away, replace the original ECM/PCM.
NO | - Check these items:

- A short or an open in the wire between the ECM/PCM (A18) and the VSS.
- If the wire is OK, test the VSS (see page 22-94).