Fuel and Emissions

DTC U0129: F-CAN Malfunction (PCM-Servo Unit)

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.

1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Check for Temporary DTCs or DTCs with the HDS.

Are DTC U0028 and U0129 indicated at the same time?

YES - Go to troubleshooting for DTC U0028.

NO - Go to step 4.

4. Clear the DTC with the HDS.
5. Check for Temporary DTCs or DTCs with the HDS.

Is DTC U0129 indicated?

YES - Go to step 6.

NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the gauge control module (tach), the servo unit, and the PCM.

6. Check for communication to the advanced hydraulic booster system with the HDS.

Does the HDS communicate with the servo unit?

YES - Check for DTCs in the hydraulic booster system with the HDS, then go to the indicated DTCs troubleshooting.

NO - Go to step 7.

7. Turn the ignition switch OFF.
8. Disconnect the servo unit 25P connector.
9. Check for continuity between body ground and servo unit 25P connector terminals No. 7, No. 23, and No. 24 individually.






Is there continuity?

YES - Substitute a known-good servo unit, then go to step 10 and recheck. If DTC U0129 is not indicated, replace the original servo unit, then go to step 10.

NO - Repair open in the wire between the servo unit (No. 7, No. 23, and/or No. 24) and G202, then go to step 10.

10. Turn the ignition switch OFF.
11. Reconnect the servo unit 25P connector.
12. Turn the ignition switch ON (II).
13. Reset the PCM with the HDS.
14. Do the PCM idle learn procedure.
15. Check for Temporary DTCs or DTCs with the HDS.

Is DTC U0129 indicated?

YES - Check for poor connections or loose terminals at the gauge control module (tach), the servo unit and the PCM, then go to step 1.

NO - Troubleshooting is complete. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTCs troubleshooting.