DTC Troubleshooting

Control System DTCs

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 How To Troubleshoot The Fuel And Emissions Systems.

1. Problem verification:

Problem verification
-1. Turn the ignition switch to ON (II).

-2. Clear the DTC with the HDS.

-3. Check for Pending or Confirmed DTCs with the HDS.

Is DTC U0155 indicated?
-YES- The failure is duplicated. Go to step 2.
-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.

2. Body electrical system DTC check:

Body electrical system DTC check
-1. Check for body electrical DTCs with the HDS.

Is DTC B1168, B1169, and/or B1178 indicated?
-YES- Go to step 3.
-NO- Do the gauge control module (tach) input test.

3. Open wire check (F_CAN-H line):

Open wire check (F_CAN-H line)
-1. Turn the ignition switch to LOCK (0).

-2. Jump the SCS line with the HDS.

-3. Disconnect the following connectors.





-4. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The F_CAN-H wire is OK. Go to step 4.
-NO- Repair an open in the F_CAN-H wire between the ECM (A3) and the gauge control module (tach), then do the repair verification.

4. Open wire check (F_CAN-L line):

Open wire check (F_CAN-L line)
-1. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The F_CAN-L wire is OK. Substitute a known-good gauge control module (tach) Gauge Control Module (Tach) Removal and Installation, then do the repair verification. If DTC U0155 is not indicated after substitution, replace the original gauge control module (tach) Gauge Control Module (Tach) Removal and Installation, then do the repair verification.
-NO- Repair an open in the F_CAN-L wire between the ECM (A4) and the gauge control module (tach), then do the repair verification.

Repair verification:

-1. Turn the ignition switch to LOCK (0).

-2. Reconnect all connectors.

-3. Turn the ignition switch to ON (II).

-4. Reset the ECM with the HDS How To Troubleshoot The Fuel And Emissions Systems.

-5. Do the ECM idle learn procedure ECM/PCM Idle Learn Procedure.

-6. Check for Pending or Confirmed 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 Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.