Test E: The Steering Wheel Controls Are Inoperative

PINPOINT TEST E: THE STEERING WHEEL CONTROLS ARE INOPERATIVE

Normal Operation
The audio unit sends a reference voltage to the steering wheel controls through circuit 595 (LB/RD). Each steering wheel control switch function corresponds with a specific resistance value within the switch. When a switch is pressed, the audio unit monitors the change in reference voltage to determine the requested function. Ground for the steering wheel controls is provided through circuit 57 (BK).

- DTC C1976 (Audio Steering Wheel Switch Circuit - Open Circuit) - sets when the reference voltage on circuit 595 (LB/RD) is too high, suggesting an open circuit.
- DTC C1977 (Audio Steering Wheel Switch Circuit Short to GND) - sets when the reference voltage on circuit 595 (LB/RD) is too low, suggesting a short to ground on circuit 595 (LB/RD) before the steering wheel controls, or internally shorted steering wheel controls.
- DTC B2404 (Audio Steering Wheel Switch Circuit Fault) - sets when any fault is detected in the steering wheel controls circuit.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Audio unit
- Clockspring
- Steering wheel controls

E1-E2:

E2-E4:

E4-E6: