DTC Descriptor
DTC B2455 00: Cellular Phone Microphone Circuit
Circuit/System Description
The vehicle communication interface module (VCIM) detects that the cellular microphone is connected through the cellular microphone signal circuit and the drain wire.
Conditions for Running the DTC
| • | The ignition must be in the RUN or ACC position. |
| • | The system voltage is at least 9.5 volts and no more than 15.5 volts. |
| • | All the above conditions are present for greater than 10 seconds. |
Conditions for Setting the DTC
| • | The VCIM detects an open in the drain wire circuit or a short to voltage in the cellular microphone signal circuit. |
| • | The above conditions are present for greater than 10 seconds. |
Action Taken When the DTC Sets
| • | The VCIM will not receive any signal from the microphone. |
| • | Calls can be placed but the caller cannot be heard. |
| • | The OnStar® status LED turns red. |
Conditions for Clearing the DTC
| • | The VCIM detects the microphone connected for 5 consecutive 100 millisecond cycles. |
| • | A history DTC clears after 50 malfunction-free ignition cycles. |
| • | The VCIM receives the clear DTC command from the scan tool. |
Reference Information
Schematic Reference
OnStar Schematics
Connector End View Reference
Cellular Communication Connector End Views
Description and Operation
OnStar Description and Operation
Electrical Information Reference
Circuit/System Testing
- Ignition OFF. Disconnect the harness connector at the cellular microphone.
- Ignition ON, test for 9 - 11 volts at signal circuit terminal B.
| ⇒ | If greater than specified value, repair short to B+ or replace the VCIM. |
| ⇒ | If less than specified value, repair short to ground or open/high resistance or replace the VCIM. |
- Disconnect the VCIM C2 harness connector.
- Test for less than 1 volt at the cellular microphone terminal A .
| ⇒ | If greater than specified value, repair short to B+. |
- Test for greater than 1 ohm of resistance between terminal A and ground
| ⇒ | If less than specified value, repair short to ground. |
- Test for less than 1 ohm of resistance between terminal A and terminal 10.
| ⇒ | If greater than the specified value, repair open/high resistance. |
- If all circuits test normal, test or replace the cellular microphone.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
