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.

Schematic Reference

Steering Wheel Secondary/Configurable Control Schematics

Connector End View Reference

Description and Operation

Steering Wheel Controls Description and Operation

Electrical Information Reference

Scan Tool Reference

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.

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

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

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

⇒	If less than the specified value, test the signal circuit for a short to ground.

7. If all circuits test normal, test or replace the steering wheel control switch.

1. Ignition OFF, disconnect the harness connector at the right steering wheel control switch.
2. Test for infinite resistance between the ignition terminal 3 and the signal terminal 6 with the switch in the open position.

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

3. Test for less than 5,400 ohms between the ignition terminal and the signal terminal with the switch closed in each position.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.