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

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.
* The VCIM receives the clear DTC command from the scan tool.

Circuit/System Testing

1. Ignition OFF. Disconnect the harness connector at the cellular microphone.
2. 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.

3. Disconnect the VCIM C2 harness connector.
4. Test for less than 1 volt at the cellular microphone terminal A.

• If greater than specified value, repair short to B+.

5. Test for greater than 1 ohm of resistance between terminal A and ground

• If less than specified value, repair short to ground.

6. Test for less than 1 ohm of resistance between terminal A and terminal 10.

• If greater than the specified value, repair open/high resistance.

7. If all circuits test normal, test or replace the cellular microphone.

Repair Instructions

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

* Control Module References for VCIM replacement, setup, and programming
* Mobile Telephone Microphone Replacement