B2840-87

B2840-87-LEFT HEADLAMP SWIVELING CONTROL - MISSING MESSAGE





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Left and Right Headlamp Leveling Control Modules (Headlamp Leveling Motors) are used to control the levels of the Front Headlamps. The Adaptive Front Lighting System (AFLS) Module communicates with these Control Modules via a LIN BUS circuit. The Headlamp Leveling Motors are integrated into both the Left and Right Headlamp Assemblies. If a motor is defective, the entire assembly must be replaced.

- When Monitored:
Continuously with the ignition on.

- Set Condition:
LIN BUS messages not received from the Left Headlamp Leveling Motor.





1. CHECK FOR AN ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, read DTCs.

Does the scan tool display this DTC as active?

Yes

- Go To 2

No

- Test complete, the condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.

2. (F927) RUN RELAY OUTPUT CIRCUIT OPEN OR SHORTED TO GROUND
1. Turn the ignition off.
2. Disconnect the Left Front Lamp Assembly C1 harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (F927) Run Relay Output circuit.

Is the voltage greater than 10.0 volts?

Yes

- Go To 3

No

- Repair the (F927) Run Relay Output circuit for an open or short to ground.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

3. (Z901) GROUND CIRCUITS OPEN
1. Turn the ignition off.
2. Measure the resistance between ground and the (Z901) Ground circuits.

Is the resistance below 5.0 Ohms?

Yes

- Go To 4

No

- Repair the open in the (Z901) Ground circuits.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

4. MEASURE THE VOLTAGE OF THE (D412) LIN BUS CIRCUIT
1. Turn the ignition on.
2. Measure the voltage of the (D412) LIN BUS circuit.

Is voltage present?

Yes

- Replace the Left Headlamp Assembly. Front Lamp Unit - Removal.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 5

5. (D412) LIN BUS CIRCUIT SHORTED TO GROUND
1. Turn the ignition off.
2. Disconnect the Adaptive Front Lighting System (AFLS) Module harness connector.
3. Measure the resistance between ground and the (D412) LIN BUS circuit.

Is the resistance below 10K Ohms?

Yes

- Repair the short to ground in the (D412) LIN BUS circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 6

6. (D412) LIN BUS CIRCUIT OPEN
1. Measure the resistance of the (D412) LIN BUS circuit.

Is the resistance below 5.0 Ohms?

Yes

- Replace the Adaptive Front Lighting System (AFLS) Module. Adaptive Front Lighting System Module - Removal.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Repair the open in the (D412) LIN BUS circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.