For 1990-2009 cars

### Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

### Circuit/System Description

The body control module (BCM) supplies voltage to the audio steering wheel control multiple momentary contact switches and monitors the return signal. Each switch is associated to a set resistance value, when pressed a specific voltage drop occurs through a series of resistors unique to that switch. The BCM identifies the selection, then sends a serial data message that is received by the component controlled, activating the feature.

### Diagnostic Aids

• | This diagnostic is for the audio steering wheel controls.

• | Before diagnosis of the steering wheel controls, ensure the primary controls of the associated component are functioning properly.

• | Review schematic when testing switch resistance values.

• | If a single switch function is inoperative, test the suspect switch. Refer to component testing.

### Reference Information

#### Schematic Reference

Steering Wheel Secondary/Configurable Control Schematics

#### Connector End View Reference

• | Data Communication Connector End Views

• | Secondary/Configurable Control Connector End Views

#### Description and Operation

Steering Wheel Controls Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

### Circuit/System Verification

Ignition ON, observe the scan tool SWC Bank 1 status while pressing and releasing the switches. The reading should be SW1-SW7 identifying the switch pressed, and Idle when released.

### Circuit/System Testing

Important: It is recommended that component testing is performed before circuit testing when diagnosing steering wheel controls.

Caution: Refer to SIR Caution in the Preface section.

1. Ignition OFF, disconnect the harness connector at the right steering wheel control switch.
2. Ignition ON, test for ignition voltage between the ignition circuit terminal 3 and ground.

⇒ | If less than specified value, test the ignition circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the BCM.

3. Test for the 0 volts between the signal circuit terminal 4 and ground.

⇒ | If greater than specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.

4. Test for ignition voltage between the ignition circuit terminal 3 and the signal circuit terminal 4.

⇒ | If less than specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM.

5. Ignition OFF, disconnect the C1 harness connector at the BCM.
6. Test for infinite resistance between the signal circuit terminal 6 and ground.

⇒ | If not the specified value, test the signal circuit for a short to ground.

7. If all circuits test normal, test or replace switch.

### Component Testing

Caution: Refer to SIR Caution in the Preface section.

1. Ignition OFF, disconnect the harness connector at the suspect steering wheel control switch.
2. Test for infinite resistance between the ignition terminal 3 and the signal terminal 4 with the switch in the open position.

⇒ | If less than specified value, replace the switch.

3. Test for less than 5400 ohms of resistance between the signal terminal 4 and the ignition terminal 3 with the switch in the closed position. .

⇒ | If greater than the specified value, replace the steering wheel control switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Steering Wheel Control Switch Assembly Replacement

• | Control Module References for BCM replacement, setup, and programming