Vehicle Speed Signal Circuit Troubleshooting

Vehicle Speed Signal Circuit Troubleshooting

Before testing:

- Check to see if diagnostic trouble code P0720 (9) is indicated. If it is, troubleshoot the DTC.
- Inspect the No. 9 (7.5 A) fuse in the driver's under-dash fuse/relay box.
- Confirm that there is continuity between the gauge assembly 14P connector C9 and C10 terminals and body ground (G501).

1. Raise the vehicle, and make sure it is securely supported.
2. Disconnect the 14P connector C from the gauge assembly.




3. Connect the C2 terminal to the positive probe of a voltmeter, and connect the negative probe to body ground. To prevent damage to the gauge assembly, lay the gauge assembly on a shop rag.
4. Put the vehicle in neutral with the ignition switch ON (II).
5. Slowly rotate (over 3 mph (2 km/h)) one wheel with the other wheel blocked.

Does voltage pulse from 0 to approx. 5 V or more?

YES - Replace the speedometer or the printed circuit board panel.

NO - Turn the ignition switch OFF, and go to step 6.




6. Connect the No. 9 terminal of the PCM connector A (32P) to the positive probe of a voltmeter, and connect the negative probe to body ground. (A/T)




7. Connect the No. 16 terminal of the ECM connector E (31P) to the positive probe of a voltmeter, and connect the negative probe to body ground. (M/T)
8. Put the vehicle in neutral with the ignition switch ON (II).
9. Slowly rotate (over 3 mph (2 km/h)) one wheel with the other wheel blocked.

Does voltage pulse from 0 to approx. 5 V or more?

YES - Repair open in the BLU/WHT wire between the gauge assembly and the PCM, the cruise control unit, or the driver's multiplex control unit the climate control unit, the driver's power seat control unit, or the navigation control unit.

NO - Turn the ignition switch OFF, and go to step 9.

10. Disconnect PCM connector A (32P).




11. Check for continuity between No. 9 terminal and body ground. (A/T)




12. Check for continuity between No. 16 terminal and body ground. (M/T)

Is there continuity?

YES - Repair short to ground in the BLU/WHT wire between the PCM and the gauge assembly, the cruise control unit, the driver's multiplex control unit the climate control unit, the driver's power seat control unit, or the navigation unit.

NO - Check for these problems:
- Bent, loose or corroded terminals.
- A faulty PCM.