Pinpoint Test E: The Steering Wheel Controls Are Inoperative
Information and Entertainment System
Pinpoint Tests
Pinpoint Test E: The Steering Wheel Controls Are Inoperative
Refer to Wiring Diagram Set 130, Audio System for schematic and connector information. Diagrams By Number
Normal Operation
The audio unit sends a reference voltage to the steering wheel controls. 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.
- DTC C1976 (Audio Steering Wheel Switch Circuit - Open Circuit) - sets when the reference voltage is too high, suggesting an open circuit.
- DTC C1977 (Audio Steering Wheel Switch Circuit Short to GND) - sets when the reference voltage is too low, suggesting a short to ground 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
PINPOINT TEST E: THE STEERING WHEEL CONTROLS ARE INOPERATIVE
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
-------------------------------------------------
E1 CHECK THE STEERING WHEEL CONTROLS RESISTANCE VALUES
- Ignition OFF.
- Disconnect: Audio Unit C290a.
- Measure the resistance between the audio unit C290a-18, circuit 595 (LB/RD), harness side and ground while pressing the steering wheel controls as follows:
- Are the resistances within specification?
Yes
INSTALL a new audio unit. REFER to Audio Unit Service and Repair. TEST the system for normal operation.
No
GO to E2.
-------------------------------------------------
E2 CHECK THE STEERING WHEEL CONTROLS SIGNAL CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Disconnect: Clockspring C218a.
- Measure the resistance between the audio unit C290a-18, circuit 595 (LB/RD), harness side and the clockspring C218a-5, circuit 595 (LB/RD), harness side; and between the audio unit C290a-18, circuit 595 (LB/RD), harness side and ground.
- Is the resistance less than 5 ohms between the audio unit and the clockspring, and greater than 10,000 ohms between the audio unit and ground?
Yes
GO to E3.
No
REPAIR the circuit. CLEAR the DTCs. TEST the system for normal operation.
-------------------------------------------------
E3 CHECK THE STEERING WHEEL CONTROLS GROUND CIRCUIT FOR AN OPEN
- Measure the resistance between the clockspring C218a-15, circuit 57 (BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to E4.
No
REPAIR the circuit. CLEAR the DTCs. TEST the system for normal operation.
-------------------------------------------------
E4 CHECK THE STEERING WHEEL CONTROLS SIGNAL CIRCUIT FOR AN OPEN IN THE STEERING WHEEL HARNESS
- Remove the driver air bag module. Refer to Restraint Systems.
- Disconnect: Clockspring C218b.
- Disconnect: Steering Wheel Controls C2208.
- Measure the resistance between the steering wheel controls C2208-5, circuit 595 (LB/RD), harness side and the clockspring C218b-9, circuit 595 (LB/RD), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to E5.
No
INSTALL a new steering wheel. REFER to Steering Column. CLEAR the DTCs. TEST the system for normal operation.
-------------------------------------------------
E5 CHECK THE STEERING WHEEL CONTROLS GROUND CIRCUIT FOR AN OPEN IN THE STEERING WHEEL HARNESS
- Measure the resistance between the steering wheel controls C2208-3, circuit 57 (BK), harness side and the clockspring C218b-7, circuit 57 (BK), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to E6.
No
INSTALL a new steering wheel. REFER to Steering Column. CLEAR the DTCs. TEST the system for normal operation.
-------------------------------------------------
E6 CHECK THE CLOCKSPRING FOR AN OPEN
- Measure the resistance between the clockspring C218a pin 5, component side and the clockspring C218b pin 9, component side; and between the clockspring C218a pin 15, component side and the clockspring C218b pin 7, component side.
- Are the resistances less than 5 ohms?
Yes
INSTALL new steering wheel controls. REFER to Steering Wheel Controls Service and Repair. INSTALL the driver air bag module. REFER to Restraint Systems. CLEAR the DTCs. TEST the system for normal operation.
No
INSTALL a new clockspring. INSTALL the driver air bag module. REFER to Restraint Systems. TEST the system for normal operation.
-------------------------------------------------