Vehicle Speed Signal Circuit Troubleshooting

Vehicle Speed Signal Circuit Troubleshooting

Before testing:

- Check to see if Diagnostic Trouble Code (DTC) P0721 (9) is indicated. If it is, troubleshoot the DTC.
- Inspect the No. 9 (10 A)fuse in the driver's under-dash fuse/relay box.
- Check for 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 gauge assembly connector C (14P).




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 towel.
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 about 5 V or more?

YES - Replace the speedmeter or the printed circuit board (PCB).

NO - Go to step 6.

6. Jump the SCS line with the Honda PGM Tester or HDS.
7. Turn the ignition switch OFF.
8. Disconnect PCM connector B(56P).




9. Check for continuity between PCM connector terminal B26 and gauge assembly connector terminal C2.

Is there continuity?

YES - Go to step 10.

NO - Repair open in the wire between the PCM (B26) and the gauge assembly.

10. Disconnect driver's multiplex control unit connector B, multi-information display unit connector B (without navigation) or navigation connector C (with navigation), climate control unit connector B, and the driver's power seat control unit connector A.




11. Check for continuity between No. 26 terminal and body ground.

Is there continuity?

YES - Repair short to ground in the BLU/WHT wire between the PCM and driver's multiplex control unit connector B, multi-information display unit connector B (without navigation), or navigation connector C (with navigation) climate control unit connector B, driver's power seat control unit connector A, or the gauge assembly connector C.

NO - Check for these problems:

- Bent, loose or corroded terminals.
- A faulty PCM.