Chevrolet Trax: DTC B2455 (ONSTAR): Cellular phone microphone

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• 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/High Resistance

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 high 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 microphone low signal circuit.

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 s.

Conditions for Setting the DTC

B2455 02

The telematics communication interface control module detects an short to ground in the cellular phone microphone high signal circuit for 10 s 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 high signal circuit for 10 s or greater.
• The telematics communication interface control module detects an open/high resistance in the microphone low signal circuit for 10 s or greater.

Action Taken When the DTC Sets

• The OnStar 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/Telematics Schematics (Encore), OnStar/Telematics Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

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 low 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 8 V

5. Test or replace the B24 Cellular Phone Microphone.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Mobile Telephone Microphone Replacement (Encore), Mobile Telephone Microphone Replacement (Trax)
• Control Module References for telematics communication interface control module replacement, programming and setup.

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