B2455
DTC B2455
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provide an overview of each diagnostic category.
DTC Descriptors
DTC B2455 00
- Cellular Phone Microphone Circuit
DTC B2455 04
- Cellular Phone Microphone Circuit Open
Diagnostic Fault Information
Circuit/System Description
The telematics communication interface control module provides the cellular phone microphone with a supplied voltage on the cellular phone microphone signal circuit. When the microphone is in use, voice data from the user is sent back to the telematics communication interface control module on the signal circuit. The telematics communication interface control module provides a ground for the cellular phone microphone via the low reference wire.
Conditions for Running the DTC
* The ignition must be in the RUN or ACC position.
* The system voltage is at least 9.5 V and no more than 15.5 V.
* All the above conditions are present for greater than 10 seconds.
Conditions for Setting the DTC
* The telematics communication interface control module detects an open, short to ground or short to voltage in the cellular phone microphone signal circuit for 10 seconds or greater.
* The telematics communication interface control module detects an open/high resistance in the low reference circuit for 10 seconds or greater.
Action Taken When the DTC Sets
* The OnStar(R) status LED turns red.
* The telematics communication interface control module will not receive a signal from the cellular phone 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.
Reference Information
Schematic Reference
OnStar Schematics (OnStar Schematics)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
OnStar Description and Operation (OnStar)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the B24 cellular phone microphone.
2. Ignition OFF and scan tool disconnected, wait until all retained accessory power is OFF, test for less than 10 ohm between the low reference circuit terminal 1 or A (depending on vehicle) and ground, allowing up to 5 minutes for the circuit resistance to drop to its lowest reading.
• If greater than the specified range, test the circuit for an open/high resistance.
3. Ignition ON, test for 9.5-10.5 V between the signal circuit terminal 2 or B (depending on vehicle) and ground.
• If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K73 telematics communication interface control module.
• If greater than the specified range, test the circuit for a short to voltage. If the circuit tests normal, replace the K73 telematics communication interface control module.
4. If all circuit test normal, replace the B24 cellular phone microphone.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Mobile Telephone Microphone Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for telematics communication interface control module replacement, setup, and programming