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 (see DTC P0721: PROBLEM IN OUTPUT SHAFT (COUNTERSHAFT) SPEED SENSOR CIRCUIT ).
• Inspect the No. 9 (10 A) fuse in the driver's under-dash fuse/relay box.
• Check for continuity between the gauge assembly 14P (or 16P*) connector C9 and C10 (or C12 and C13)* terminals and body ground (G501).

1. Raise the vehicle, and make sure it is securely supported.
2. Disconnect gauge assembly connector C (14P or 16P*).
3. Connect the C2 (or C3*) 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.

   *: '04-'06 models

   Fig 1: Connecting C2 Terminal To Positive Probe Of Voltmeter And Connecting Negative Probe To Body Ground ('03 Model)

   Courtesy of AMERICAN HONDA MOTOR CO., INC.
   Fig 2: Connecting C3 Terminal To Positive Probe Of Voltmeter And Connecting Negative Probe To Body Ground ('04-06 Models)

   Courtesy of AMERICAN HONDA MOTOR CO., INC.
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? 

   1. YES  - Replace the speedometer or the printed circuit board (PCB).
   2. NO  - Go to step 6.
6. Jump the SCS line with the 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 (or C3*).

   *: '04-'06 models

   Fig 3: Checking Continuity Between PCM Connector Terminal B26 And Gauge Assembly Connector Terminal C2 (Or C3*)

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   Is there continuity? 

   1. YES  - Go to step 10.
   2. 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 PCM connector terminal B26 and body ground.
    Fig 4: Checking Continuity Between PCM Connector Terminal B26 And Body Ground

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. 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.
    2. NO  - Check for these problems:
       • Bent, loose or corroded terminals.
       • A faulty PCM.