Diagnostic Fault Information
Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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. |
Reference Information
Schematic Reference
Steering Wheel Schematics
Connector End View Reference
Electrical Information Reference
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
Note: It is Recommend that Component Testing is performed before Circuit Testing when diagnosing steering wheel controls.
Caution: Refer to SIR Caution in the Preface section.
- Ignition OFF, disconnect the harness connector at the audio steering wheel control switch.
- Ignition ON, test for 10-12 volts between the voltage circuit and ground at the right switch harness connector.
| ⇒ | If less than 10 volts, test the voltage circuit for short to ground or open/high resistance. If circuit test normal, replace BCM. |
- Install a 3-amp fused jumper wire between the voltage circuit and the signal circuit at the right harness connector. Verify DTC B2815 sets.
| ⇒ | If DTC B2815 does not set, test the signal circuit for a short to ground or open/high resistance. If circuit test normal, replace BCM. |
- If circuits test normal, refer to component testing.
Component Testing
Caution: Refer to SIR Caution in the Preface section.
- Ignition OFF, disconnect the harness connector at the audio steering wheel control switch.
- Test the switch for infinite resistance between the voltage terminal and the signal terminal with the switch in the open position.
| ⇒ | If less than infinite resistance, replace the switch. |
- Test resistance values between the 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
Important: Always perform the after completing the diagnostic procedure.
