OnStar Microphone Malfunction
OnStar Microphone Malfunction
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 provides an overview of each diagnostic category.
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 cellular phone microphone is in use, voice data from the user is sent back to the telematics communication interface control module on the signal circuit.
Reference Information
Schematic Reference
OnStar Schematics OnStar Schematics
Connector End View Reference
Component Connector End Views Sunshade - Left
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 not set.
• If DTC B2455 is set
Refer to DTC B2455 B2455.
• If DTC B2455 is not set
3. Verify that a successful OnStar voice command can be made.
• If your voice can not be heard clearly
Refer to Circuit/System Testing - Microphone Malfunction.
• If your voice can be heard clearly
4. 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 - Cellular Telephone Voice Malfunction.
• If your voice can be heard clearly
5. All OK.
Circuit/System Testing
Microphone Malfunction
1. Ignition OFF, disconnect the harness connector at the B24 Cellular Phone Microphone, ignition ON.
2. Test for 8.0-10.5 V between the signal circuit terminal B and ground.
• If less than 8.0 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 8.0-10.5 V
3. Test for less than 1 V between the signal 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
4. Test for greater than 8 V between the signal circuit terminal B and the signal circuit terminal A.
• If less than 8 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 9 V
5. Test or replace the B24 Cellular Phone Microphone.
Cellular Telephone Voice Malfunction
1. Ignition OFF and vehicle systems OFF, disconnect the X2 harness connector at the K73 Telematics Communication Interface Control Module and the X4 harness connector at the A11 Radio, ignition ON.
2. Test for less than 1 V between the signal circuits listed below and ground.
* K73 Telematics Communication Interface Control Module signal circuit Terminal 6
* K73 Telematics Communication Interface Control Module signal circuit Terminal 15
• If greater than 1 V
Repair the short to voltage in the circuit.
• If less than 1 V
3. Ignition OFF.
4. Test for infinite resistance between the between the signal circuits listed below and ground.
* K73 Telematics Communication Interface Control Module signal circuit Terminal 6
* K73 Telematics Communication Interface Control Module signal circuit Terminal 15
• If less than infinite resistance
Repair the short to ground on the circuit.
• If infinite resistance
5. Test for less than 2 ohms in the the signal circuits listed below end to end.
* K73 Telematics Communication Interface Control Module signal circuit Terminal 6
* K73 Telematics Communication Interface Control Module signal circuit Terminal 15
• If 2 ohms or greater
Repair the open/high resistance in the circuit.
• If less than 2 ohms
6. Replace the K73 Telematics Communication Interface Control Module.
7. 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
Replace the A11 Radio.
• If your voice can be heard clearly
8. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair procedure.
* Mobile Telephone Microphone Replacement Service and Repair
* Control Module References Control Module References for radio or telematics communication interface control module replacement, programming, and setup.