Vehicle Speed Signal Circuit Troubleshooting

Vehicle Speed Signal Circuit Troubleshooting

Special Tools Required
Test Harness 07LAJ-PT3020A

Before testing, inspect the No. 4 (7.5 A) fuse in the under-dash fuse/relay box.




1. Disconnect the 3P connector from the VSS (vehicle speed sensor) (A).

2. Connect the test harness only to the engine wire harness and the VSS.
3. Connect the RED test harness clip (B) to the positive probe of an ohmmeter. Cover the white (C) and green (D) test harness with protective tape (E).
4. Turn the ignition switch ON (II).
5. Check for voltage between the RED test harness clip and body ground.

Is there less than 1 V?

YES - Go to step 6.

NO - Repair open or loose connection on the BLK wire between the VSS and G101.

6. Turn the ignition switch OFF.




7. Connect the WHT test harness clip (C) to the positive probe of a voltmeter, and connect the RED test harness clip (B) to the negative probe.

8. Turn the ignition switch ON (II).

Is there battery voltage?

YES - Go to step 9.

NO - Repair open in the BLK/YEL wire between the VSS and the under-dash fuse/relay box.

9. Disconnect the WHT test harness clip (C).
10. Disconnect the test harness from the VSS (A).




11. Connect the GRN test harness clip (D) to the positive probe of a voltmeter.

Is there 5 V or more?

YES - Go to step 12.

NO - Repair short in the BLU/WHT wire between the VSS and the ECM.

12. Turn the ignition switch OFF.




13. Connect the other test harness connector (A) to the VSS(B).
14. Raise the front of the vehicle, and make sure it is securely supported.
15. Put the vehicle in neutral with the ignition switch ON (II).
16. Slowly rotate one wheel with the other wheel blocked.

Does voltage pulse from 0 to about 5 V or more ?

YES - Go to step 17.

NO - Replace the VSS.

17. Disconnect gauge assembly connector A (30P).




18. Connect a voltmeter between the BLU/WHT wire and body ground.
19. Slowly rotate one wheel with the other wheel blocked.

Does the meter indicate pulsing voltage?

YES - Replace the speedometer.

NO - Repair open in the BLU/WHT wire between the VSS and the speedometer.