DTC Troubleshooting

DTC Troubleshooting: U0155

DTC U0155: F-CAN Malfunction (ECM-Gauge Control Module)

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

1. Turn the ignition switch to ON (II).

2. Clear the DTC with the HDS.

3. Check for Temporary DTCs or DTCs with the HDS.

Is DTC U0155 indicated?
YES - Go to step 4.

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


4. Check for body electrical DTCs in the DTCs MENU with the HDS.

Is DTC B1168, B1169, and/or B1178 indicated?
YES - Go to step 5.

NO - Do the gauge control module (tach) input test. Gauge Control Module (Tach) Input Test


5. Turn the ignition switch to LOCK (0).

6. Jump the SCS line with the HDS.

7. Remove the gauge control module (tach). Gauge Control Module Replacement

8. Disconnect the gauge control module (tach) 36P connector.

9. Disconnect ECM connector A (44P).

10. Connect gauge control module (tach) 36P connector terminal No. 1 to body ground with a jumper wire.






11. Check for continuity between ECM connector terminal A36 and body ground.

Is there continuity?
YES - Go to step 12.

NO - Repair open in the wire between the ECM (A36) and the gauge control module (tach), then go to step 14.






12. Connect gauge control module (tach) 36P connector terminal No. 19 to body ground with a jumper wire.






13. Check for continuity between ECM connector terminal A37 and body ground.

Is there continuity?
YES - Substitute a known-good gauge control module (tach), Gauge Control Module Replacement then go to step 14 and recheck. If no DTCs are indicated, replace the original gauge control module (tach), Gauge Control Module Replacement then go to step 14.

NO - Repair open in the wire between the ECM (A37) and the gauge control module (tach), then go to step 14.






14. Reconnect all connectors.

15. Turn the ignition switch to ON (II).

16. Reset the ECM with the HDS.

17. Do the ECM idle learn procedure. ECM Idle Learn Procedure

18. Check for Temporary DTCs or DTCs with the HDS.

Is DTC U0155 indicated?
YES - Check for poor connections or loose terminals at the gauge control module (tach) and the ECM, then go to step 1.

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