B2455

DTC B2455

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provide an overview of each diagnostic category.



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(R) 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.



Reference Information
Schematic Reference

OnStar Schematics (OnStar Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

OnStar Description and Operation (OnStar Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)



Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the inside rearview mirror.
2. Ignition ON, test for greater than 9 volts between the signal circuit terminal 10 and ground.

• If less than specified range, test the signal circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the VCIM.

3. Test for greater than 9 volts between the signal circuit terminal 10 and the drain circuit terminal 2.

• If less than specified range, test the drain wire for an open/high resistance. If the circuit tests normal, replace the VCIM.

4. If all circuit test normal, test or replace the cellular microphone assembly.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Control Module References (Programming and Relearning) for VCIM replacement, setup, and programming
* Mobile Telephone Microphone Replacement (Service and Repair)