B1407

DTC B1407 (3-4); OnStar Control Unit Lost Communication with Driver's MPCS Unit (ASLOCKSW 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 B1407 (3-4) 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 DTCs B1013 and B1615 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.