Pinpoint Test AA: DTC B1A98:88

Adaptive Headlighting

Pinpoint Test AA: DTC B1A98:88

- DTC B1A98:88 (LIN Bus Circuit #1: Bus off)- sets continuous and on-demand by the Headlamp Control Module (HCM) if communication is lost to the headlamps due to a circuit fault on the communication circuit between the HCM (Headlamp Control Module) and the headlamps.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- Headlamp assembly

- HCM (Headlamp Control Module)

PINPOINT TEST AA : DTC B1A98:88

AA1 ISOLATE THE LH HEADLAMP ASSEMBLY AS THE CAUSE OF THE DTC

- Ignition OFF.

- Disconnect: LH Headlamp Assembly C1021.

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: HCM (Headlamp Control Module) Self-Test.

- NOTE: Other DTCs can be present with the headlamp assembly disconnected and should be ignored.
Clear the DTCs and repeat the HCM (Headlamp Control Module) self-test.


Is DTC B1A98:88 still present?

Yes
GO to AA2.

No
INSTALL a new LH headlamp assembly. REFER to Headlamp Assembly . CLEAR the DTCs. REPEAT the self-test.

AA2 ISOLATE THE RH HEADLAMP ASSEMBLY AS THE CAUSE OF THE DTC

- Ignition OFF.

- Disconnect: RH Headlamp Assembly C1041.

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: HCM (Headlamp Control Module) Self-Test.

- NOTE: Other DTCs can be present with the headlamp assembly disconnected and should be ignored.
Clear the DTCs and repeat the HCM (Headlamp Control Module) self-test.


Is DTC B1A98:88 still present?

Yes
GO to AA3.

No
INSTALL a new RH headlamp assembly. REFER to Headlamp Assembly . CLEAR the DTCs. REPEAT the self-test.

AA3 CHECK THE COMMUNICATION CIRCUITS TO THE HEADLAMPS FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Disconnect: HCM (Headlamp Control Module) C1600.

- Ignition ON.

- Measure the voltage between the HCM (Headlamp Control Module) C1600-17, circuit VLF32 (YE), harness side, and ground; and the HCM (Headlamp Control Module) C1600-18, circuit VLF33 (BU), harness side, and ground.





Is any voltage present?

Yes
REPAIR circuit VLF32 (YE) (LH headlamp) or circuit VLF33 (BU) (RH headlamp) for a short to voltage. CLEAR the DTCs. REPEAT the self-test.

No
GO to AA4.

AA4 CHECK THE COMMUNICATION CIRCUITS TO THE HEADLAMPS FOR A SHORT TO GROUND

- Ignition OFF.

- Measure the resistance between the HCM (Headlamp Control Module) C1600-17, circuit VLF32 (YE), harness side, and ground; and the HCM (Headlamp Control Module) C1600-18, circuit VLF33 (BU), harness side, and ground.





Is the resistance greater than 10,000 ohms?

Yes
GO to AA5.

No
REPAIR circuit VLF32 (YE) (LH headlamp) or circuit VLF33 (BU) (RH headlamp) for a short to ground. CLEAR the DTCs. REPEAT the self-test.

AA5 CHECK FOR CORRECT HCM (Headlamp Control Module) OPERATION

- Disconnect all the HCM (Headlamp Control Module) connectors.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect all the HCM (Headlamp Control Module) connectors and make sure they seat correctly.

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new HCM (Headlamp Control Module). REFER to Headlamp Control Module (HCM) . 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.