For 1990-2009 cars only
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provide an overview of each diagnostic category. |
DTC Descriptor
DTC B1446: Replace Backup Power SourceCircuit/System Description
The vehicle communication interface module (VCIM) detects the Back-up Battery (BUB) is no longer able to meet the minimum requirements to successfully place a call in the event of a main battery disconnect during a collision event.
Conditions for Running the DTC
| • | Ignition is in the RUN or ACC position. |
| • | System voltage is between 9.5 and 15.5 volts. |
| • | DTC B1447 is not set. |
Conditions for Setting the DTC
The VCIM detects that the back-up battery voltage has dropped below the minimum threshold value.
Action Taken When the DTC Sets
The OnStar® status LED turns red.
Conditions for Clearing the DTC
| • | A current DTC will clear when the VCIM detects the voltage of the back-up battery is above the minimum threshold value. |
| • | A history DTC clears after 50 malfunction-free ignition cycles. |
Reference Information
Schematic Reference
Connector End View Reference
Entertainment/Communication Connector End Views
Description and Operation
OnStar Description and Operation
Electrical Information Reference
Circuit/System Testing
- Ignition OFF, disconnect the harness connector C1 at the VCIM.
- Measure for greater than 15.5 volts between terminals 13 and 14.
- If all circuits test normal, replace the VCIM.
| ⇒ | If less than specified voltage, test the battery backup supply voltage circuit and battery backup low reference circuit for an open/high resistance. If the circuit tests normal, replace the BUB. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for VCIM replacement, setup and programming |
