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 02
- Cellular Phone Microphone Circuit Short to Ground
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
B2455 02
The telematics communication interface control module detects an short to ground in the cellular phone microphone signal circuit for 10 seconds or greater.
B2455 04
The following conditions will set this DTC:
* The telematics communication interface control module detects an open/high resistance 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 Fuel Pump and Level Sensor Assembly
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 Control Module References for scan tool information
Circuit/System Verification
Note: It is necessary to have the vehicle in a quiet, open outside area where a cellular call can be successfully placed and GPS data can be received from satellites.
1. Ignition ON.
2. Verify that DTC B2455 is set.
• If DTC B2455 is not set
Refer to OnStar Microphone Malfunction OnStar Microphone Malfunction.
• If DTC B2455 is set
3. Verify that your voice is heard clearly by the OnStar Call Center after completing a blue button press.
• If your voice can not be heard clearly
Refer to Circuit/System Testing.
• If your voice can be heard clearly
4. All OK.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the B24 cellular phone microphone, ignition ON.
2. Test for 9.5-10.5 V between the signal+ circuit terminal B and ground.
• If less than 9.5 V
1. Ignition OFF, disconnect the X2 harness connector at the K73 telematics communication interface control module.
2. Test for infinite resistance between the signal+ circuit and ground.
• If less than infinite resistance, repair the short to ground in the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the signal+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the vehicle K73 telematics communication interface control module.
• If greater than 10.5 V
1. Ignition OFF, disconnect the X2 harness connector at the K73 telematics communication interface control module, ignition ON.
2. Test for less than 1 V between the signal+ circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K73 telematics communication interface control module.
• If between 9.5-10.5 V
3. Ignition ON.
4. Test for less than 1 V between the singal- circuit terminal A and ground.
• If greater than 1 V
1. Ignition OFF, disconnect the X2 harness connector at the K73 telematics communication interface control module, ignition ON.
2. Test for less than 1 V between the signal- circuit and ground.
• If 1 V or greater, repair the short to voltage in the circuit.
• If less than 1 V, repair the K73 telematics communication interface control module.
• If less than 1 V
5. Test for 9.5-10.5 V between the signal+ circuit terminal B and the signal- circuit terminal A.
• If not between 9.5-10.5 V
1. Ignition OFF, disconnect the connector X2 at the K73 telematics communication interface control module.
2. Test for infinite resistance between the signal- circuit and ground.
• If less than infinite resistance, repair the short to ground in the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the signal- circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K73 telematics communication interface control module.
• If between 9.5-10.5 V
6. Test or replace the B24 cellular phone microphone.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Mobile Telephone Microphone Replacement Service and Repair
* Control Module References Control Module References for telematics communication interface control module replacement, programming and setup.