B2455

DTC B2455

Diagnostic Instructions

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

DTC Descriptor

DTC B2455 00
- Cellular Phone Microphone Circuit

Diagnostic Fault Information






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

* Radio ON.
* Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

* The VCIM detects a short to voltage in the cellular microphone signal circuit for 10 seconds or greater.
* The VCIM detects an open/high resistance in the drain wire circuit for 10 seconds or greater.

Actions Taken When the DTC Sets

* The OnStar(R) status LED turns red.
* The VCIM will not receive a signal from the microphone.
* Calls can be placed but the caller cannot be heard.

Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the cellular microphone.
2. Ignition ON, test for 8.5-9.5 volts between the cellular microphone signal circuit terminal B and ground.

• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the VCIM.

• If less than the 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. Ignition ON, test for 8.5-9.5 volts between the cellular microphone signal circuit terminal B and the drain wire circuit terminal A.

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

4. If all circuits test normal, replace the cellular microphone.

Repair Instructions

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

* Mobile Telephone Microphone Replacement