Steering Wheel Controls Inoperative (Mute)

Steering Wheel Controls Inoperative (Mute)

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview

Circuit/System Description

The body control module (BCM) supplies voltage to the MUTE switch through the Ignition 1 voltage circuit and monitors the Cellular telephone voice signal circuit. When the switch is pressed the BCM identifies the selection, then sends a serial data message that is received by the component controlled, activating the feature.

Diagnostic Aids

* Before diagnosis of the steering wheel control, ensure the primary controls of the associated component is functioning properly.
* Pressing and holding the Mute button duplicates pressing the phone icon on the rear view mirror for OnStar ready.

Circuit/System Testing

Note: It is Recommend that Component Testing is performed before Circuit Testing when diagnosing steering wheel controls.

Caution: Refer to Restraint System Service Precautions.

1. Ignition OFF, disconnect the harness connector at the MUTE switch.
2. Ignition ON, test for 10-12 volts between the ignition 1 voltage circuit and ground at the switch harness connector.

• If less than 10 volts, test the voltage circuit for short to ground or open/high resistance. If circuit test normal and the fuse is open, test the signal circuit for a short to ground.

3. Connect test lamp between the signal circuit and ground at the harness connector. Verify test lamp does not illuminate.

• If test lamp illuminates, test the signal circuit for short to voltage. If circuit test normal, replace BCM.

4. Test for 10-12 volts between the voltage circuit and the signal circuit at the harness connector.

• If less than 10 volts, test the signal circuit for an open/high resistance. If the circuit test normal and the fuse is open, test the signal circuit for a short to ground.

5. If all circuits test normal, refer to component testing.

Component Testing

Caution: Refer to Restraint System Service Precautions.

1. Ignition OFF, disconnect the harness connector at the MUTE switch.
2. Test for infinite resistance between the ignition 1 terminal and the voice signal terminal with the switch in the open position.

• If not the specified value, replace the switch.

3. Test for less than 1.5 ohms of resistance between the voltage terminal and the voice signal terminal with the switch closed.

• If greater than specified, replace faulty switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Steering Wheel Control Switch Assembly Replacement
* Refer to Programming and Relearning for BCM replacement, setup, and programming. Programming and Relearning