Steering Wheel Controls Inoperative

Steering Wheel Controls Inoperative

Diagnostic Fault Information
Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

Circuit/System Description
The body control module (BCM) supplies 12 volts 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 with the schematic when testing switch resistance values.
^ If a single switch function is inoperative, test the suspect switch. Refer to component testing.
^ A poor connection at the right switch could cause the left switch to malfunction or be inoperative.

Reference Information

Schematic Reference

Steering Wheel Schematics

Connector End View Reference
^ Steering Wheel and Column Connector End Views
^ Computer/Integrating Systems Connector End Views

Electrical Information Reference

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

Circuit/System Verification
Ignition ON, observe the scan tool steering wheel controls (SWC) Switch Voltage parameter in the BCM data list. Pressing the switch should read voltage present, and drop to 0 volts when released.

Circuit/System Testing
It is recommended that Component Testing is performed before Circuit Testing when diagnosing steering wheel controls.

Caution: Refer to SIR Caution:

1. Ignition OFF, disconnect the harness connector at the audio steering wheel control switches.
2. Ignition ON, test for 12 volts between the voltage supply circuit and ground at the right switch harness connector.
^ If less than 10 volts, test the voltage supply circuit for a short to ground or an open/high resistance. If circuit tests normal, replace the BCM.
3. Install a 3-amp fused jumper wire at the right switch supply voltage circuit. Toggle the jumper wire to the signal circuits at the left and the right harness connectors. Verify DTC B2815 sets. B2815
^ If DTC B2815 does not set, test the signal circuits for a short to ground or an open/high resistance. If circuits test normal, replace the BCM.
4. Remove the 3-amp fused jumper wire.
5. Ignition OFF, test the jumper wire for less than 1.0 ohm of resistance between the left and right switch connectors.
^ If greater than 1.0 ohm, test the jumper wire circuit for an open/high resistance.
6. If circuit tests normal, test or replace the switch.

Component Testing

Caution: Refer to SIR Caution:

1. Ignition OFF, disconnect the harness connector at the suspect audio steering wheel control switch.
2. Test the switch for infinite resistance between the supply voltage terminal and the signal terminal with the switch in the open position.
^ If less than infinite resistance, replace the switch.
3. Test resistance values between the supply voltage terminal and the signal terminal with the switch closed in each position and verify readings are approximate to what the schematic reads.
^ If values do not, replace the switch.

Repair Instructions
Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
^ Steering Wheel Control Switch Assembly Replacement.
^ Control Module References for BCM replacement, setup, and programming.