B1406

DTC B1406 (3-3): OnStar Control Unit Lost Communication with Driver's MPCS Unit (Door Look Switch Message)

NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test mode A.

1. Delete the DTCs.
2. Turn the ignition switch OFF, and then back ON (II).
3. Check for DTCs.

Is DTC B1406 (3-3) indicated?

YES - Go to step 4.

NO - Intermittent failure. The system is OK at this time. Check for loose or poor connections.
4. Check for DTCs with the HDS.

Are DTC B1015, B1065, B1182 and B1614 also indicated?

YES - Go to the driver's MPCS unit input test. Driver's MPCS Unit Input Test If the driver's MPCS unit input test is OK, replace the OnStar control unit.

NO - Replace the OnStar control unit.