Pinpoint Test AF: DTC C1278

Adaptive Headlighting

Pinpoint Tests

Pinpoint Test AF: DTC C1278

Normal Operation

- DTC C1278 (Steering Wheel Angle 1 and 2 Signal Faulted) - an on-demand DTC that sets when the Headlamp Control Module (HCM) receives incorrect steering wheel angle data from the Steering Angle Sensor Module (SASM).

This pinpoint test is intended to diagnose the following:

- HCM
- SASM



PINPOINT TEST AF: DTC C1278

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AF1 REPEAT THE HCM SELF-TEST


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: HCM Self-Test.
- Clear the DTCs and repeat the HCM self-test.
- Is DTC C1278 retrieved again?

Yes
GO to AF2.

No
The vehicle is operating correctly at this time. The HCM may have temporarily received incorrect data from the SASM.

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AF2 CHECK THE ABS MODULE FOR DTC C1278


- Carry out the self-test for the ABS module.
- Is DTC C1278 retrieved?

Yes
GO to AF3.

No
GO to AF4.

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AF3 CHECK FOR CORRECT SASM OPERATION


- Disconnect the SASM connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the SASM connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new SASM. REFER to Steering Wheel Rotation Sensor in Antilock Brakes / Traction Control Systems. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

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AF4 CHECK FOR CORRECT HCM OPERATION


- Disconnect the HCM connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the HCM connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new HCM. REFER to Headlamp Control Module (HCM) Service and Repair. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

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