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 01
- Cellular Phone Microphone Circuit Short to Battery

DTC B2455 02
- Cellular Phone Microphone Circuit Short to Ground




Circuit/System Description

The navigation radio 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 navigation radio detects a short to ground 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 navigation radio 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 navigation radio detects the microphone connected for 5 consecutive 100 millisecond cycles.
* A history DTC clears after 50 malfunction-free ignition cycles.
* The navigation radio receives the clear DTC command from the scan tool.



Reference Information
Schematic Reference

OnStar Schematics (OnStar Schematics)
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 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 navigation radio.
• If less than specified value, repair short to ground or open/high resistance or replace the navigation radio.

3. Disconnect the navigation radio X4 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 between terminal A and ground

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

6. Test for less than 1 ohm between terminal A and terminal 16.

• 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 (Verification Tests) after completing the diagnostic procedure.

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