Vehicle Speed Signal Circuit Troubleshooting
Vehicle Speed Signal Circuit TroubleshootingSpecial Tools Required
Test harness 07LAJ-PT3020A
Before testing, inspect the No. 4 (10 A) and No. 10 (7.5 A) fuses in the under-dash fuse/relay box.
1. Disconnect the 3P connector from the vehicle speed sensor (VSS) (A).
2. Connect the test harness only to the engine wire harness.
3. Connect the RED test harness clip (B) to the positive probe of an Ohmmeter. Cover the white (C) and green (D) test harness leads with protective tape (E).
4. Check for continuity between the RED test harness clip and body ground.
Is there continuity?
YES - Go to step 5.
NO - Repair open in the BLK wire between the VSS and G101.
5. Connect the WHT test harness clip (B) to the positive probe of a voltmeter, and connect the RED test harness clip (C) to the negative probe.
6. Connect the test harness to the VSS.
7. Turn the ignition switch ON (II).
Is there battery voltage?
YES - Go to step 8.
NO - Repair open in the BLK/YEL or BLK/ORN wire between the VSS and the under-dash fuse/relay box, repair ground or open in BLK wire between VSS and G101.
8. Disconnect the WHT test harness clip (B).
9. Disconnect the test harness from the VSS.
10. Connect the GRN test harness clip (D) to the positive probe of a voltmeter.
Is there 5 V or more?
YES - Go to step 11.
NO - Repair short or open in the BLU/WHT or WHT/GRN wire between the VSS and the cruise control unit, the gauge assembly or the ECM.
11. Turn the ignition switch OFF.
12. Connect the other test harness connector (A) to the VSS (B).
13. Raise the front of the vehicle, and make sure it is securely supported.
14. Put the vehicle in neutral with the ignition switch ON (II).
15. Slowly rotate one wheel with the other wheel blocked.
Does voltage pulse from 0 to about 5 V?
YES - Go to step 16.
NO - Replace the VSS.
16. Disconnect the 22P connector "B" from the gauge assembly.
17. Connect the positive probe of a voltmeter to the BLU/WHT wire and the negative probe to ground.
18. Slowly rotate one wheel with the other wheel blocked.
Does voltage pulse from 0 to about 5 V?
YES - Replace the speedometer assembly.
NO - Repair open in the BLU/WHT wire between the VSS and the speedometer.