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 and the harness connector X2 at the VCIM.
2. Test for less than 1 ohm of resistance between terminal A and terminal 10.

^ If greater than the specified value, test the drain wire circuit for an open/high resistance.

3. Reconnect the harness connector X2 at the VCIM.
4. Ignition ON, test for less than 9.5 volts at the signal circuit terminal B.

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

5. 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

* Mobile Telephone Microphone Replacement