Motor Control Module
DTC Troubleshooting: U0038 (99), U1204 (55)
DTC U0038:
IMA-CAN Malfunction (BUS-OFF (Motor Control Module (MCM)))
DTC U1204:
IMA-CAN Malfunction (Powertrain Control Module (PCM) - Motor Control Module (MCM))
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. Check for ENGINE COOLANT TEMPERATURE in the IMA DATA LIST with the HDS.
Is 419 °F (215 °C) indicated?
YES -
Go to step 3.
NO -
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the ECM/PCM and the MCM.
3. Jump the SCS line with the HDS.
4. Turn the ignition switch to LOCK (0).
5. Disconnect ECM/PCM connector A (44P).
6. Measure the resistance between ECM/PCM connector terminals A38 and A39.
Is there about 120 Ohms?
YES -
Go to step 19.
NO -
Go to step 7.
7. Measure the resistance between ECM/PCM connector terminals A38 and A39.
Is there about 0 Ohms?
YES -
Go to step 8.
NO -
Go to step 13.
8. Turn the battery module switch OFF.
9. Remove the IPU cover IPU Cover Removal/Installation.
10. Remove the PCU lid, the PCU busplate, and the PCU cover Service and Repair.
11. Disconnect MCM connector A (31P).
12. Check for continuity between MCM connector terminals A1 and A2.
Is there continuity?
YES -
Repair a short in the wire between MCM connector terminals A1 and A2, then go to step 32.
NO -
Go to step 38.
13. Turn the battery module switch OFF.
14. Remove the IPU cover IPU Cover Removal/Installation.
15. Remove the PCU lid, the PCU busplate, and the PCU cover Service and Repair.
16. Disconnect MCM connector A (31P).
17. Check for continuity between MCM connector terminal A2 and ECM/PCM connector terminal A38.
Is there continuity?
YES -
Go to step 18.
NO -
Repair an open in the wire between the ECM/PCM (A38) and the MCM (A2), then go to step 32.
18. Check for continuity between MCM connector terminal A1 and ECM/PCM connector terminal A39.
Is there continuity?
YES -
Go to step 38.
NO -
Repair an open in the wire between the ECM/PCM (A39) and the MCM (A1), then go to step 32.
19. Turn the ignition switch to LOCK (0).
20. Turn the battery module switch OFF.
21. Remove the IPU cover IPU Cover Removal/Installation.
22. Remove the PCU lid, the PCU busplate, and the PCU cover Service and Repair.
23. Disconnect MCM connector A (31P).
24. Check for continuity between MCM connector terminal A2 and body ground.
Is there continuity?
YES -
Repair a short to ground in the wire between the ECM/PCM (A38) and the MCM (A2), then go to step 32.
NO -
Go to step 25.
25. Check for continuity between MCM connector terminal A1 and body ground.
Is there continuity?
YES -
Repair a short to ground in the wire between the ECM/PCM (A39) and the MCM (A1), then go to step 32.
NO -
Go to step 26.
26. Turn the ignition switch to ON (II).
27. Measure the voltage between MCM connector terminal A2 and body ground.
Is there about 5-12 V?
YES -
Repair a short to power in the wire between the ECM/PCM (A38) and the MCM (A2), then go to step 32.
NO -
Go to step 28.
28. Measure the voltage between MCM connector terminal A1 and body ground.
Is there about 5-12 V?
YES -
Repair a short to power in the wire between the ECM/PCM (A39) and the MCM (A1), then go to step 32.
NO -
Go to step 29.
29. Turn the ignition switch to LOCK (0).
30. Reconnect ECM/PCM connector A (44P).
31. Measure the resistance between MCM connector terminals A1 and A2.
Is there about 120 Ohms?
YES -
Go to step 38.
NO -
Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM, then go to step 32.
32. Reconnect all connectors.
33. Reinstall the PCU cover, the PCU busplate, and the PCU lid Service and Repair.
34. Reinstall the IPU cover IPU Cover Removal/Installation, then turn the battery module switch ON.
35. Turn the ignition switch to ON (II).
36. Clear the DTC with the HDS.
37. Check for Pending or Confirmed DTCs in the IMA SYSTEM with the HDS.
Is DTC U0038 or U1204 indicated?
YES -
Check for poor connections or loose terminals at the ECM/PCM and the MCM, 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.
38. Reconnect all connectors.
39. Reinstall the PCU cover, the PCU busplate, and the PCU lid Service and Repair.
40. Reinstall the IPU cover IPU Cover Removal/Installation, then turn the battery module switch ON.
41. Update the MCM if it does not have the latest software Testing and Inspection, or substitute a known-good MCM.
42. Turn the ignition switch to ON (II).
43. Check for Pending or Confirmed DTCs with the HDS in the IMA SYSTEM.
Is DTC U0038 or U1204 indicated?
YES -
Check for poor connections or loose terminals at the ECM/PCM and the MCM. If the MCM was updated, substitute a known-good MCM, then recheck. If the MCM was substituted, go to step 1.
NO -
If the MCM was updated, troubleshooting is complete. If the MCM was substituted, replace the original MCM Service and Repair. If any other Pending or Confirmed DTCs were indicated, go to the indicated DTC's troubleshooting.