U1220

DTC U1220 (34): DC-DC Converter Lost Communication with Motor Control Module (MCM)
1. Turn the ignition switch ON (II).
2. Reset the MCM.
3. Check for Temporary DTCs or DTCs with the HDS.
Is DTC U1220 indicated?
YES - Go to step 4.
NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the DC-DC converter and the MCM.

4. Turn the ignition switch OFF.
5. Turn the battery module switch OFF.
6. Remove the IPU lid.
7. Disconnect MCM connector B (24P).
8. Disconnect the DC-DC converter 4P connector.
9. Check for continuity between MCM connector terminal B19 and body ground.





Is there continuity?
YES - Repair short in the wire between the DC-DC converter and the MCM (B19), then go to step 15.
NO - Go to step 10.

10. Check for continuity between MCM connector terminal B19 and DC-DC converter 4P connector terminal No. 2.





Is there continuity?
YES - Go to step 11.
NO - Repair open in the wire between the DC-DC converter and the MCM (B19), then go to step 15.

11. Turn the ignition switch ON (II).
12. Reset the MCM.
13. Substitute a known-good DC-DC converter.
14. Check for Temporary DTCs or DTCs with the HDS.
Is DTC U1220 indicated?
YES - Go to step 21.
NO - Replace the original DC-DC converter, then go to step 15.

15. Turn the ignition switch OFF.
16. Reconnect all connectors.
17. Reinstall the IPU lid, then turn the battery module switch ON.
18. Turn the ignition switch ON (II).
19. Reset the MCM.
20. Check for Temporary DTCs or DTCs with the HDS.
Are any Temporary DTCs or DTCs indicated?
YES - If DTC U1220 is indicated, check for poor connections or loose terminals at the DC-DC converter and the MCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO - Troubleshooting is complete.

21. Reinstall the IPU lid, then turn the battery module switch ON.
22. Update the MCM if it does not have the latest software, or substitute a known-good MCM.
23. Check for Temporary DTCs or DTCs with the HDS.
Are any Temporary DTCs or DTCs indicated?
YES - If DTC U1220 is indicated, check for poor connections or loose terminals at the DC-DC converter and the MCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO - If the MCM was updated, troubleshooting is complete. If the MCM was substituted, replace the original MCM.