Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC B0984 00: Left Headlamp Light Distribution Shutter Control Circuit MalfunctionDTC B0985 00: Right Headlamp Light Distribution Shutter Control Circuit Malfunction
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Headlamp Motor Supply | B0984 00 | B0984 00 | B0984 00 | -- |
Headlamp Motor Ground | B0985 00 | B0985 00 | B0985 00 | -- |
Headlamp Motor Module | 1 | 1 | 1 | -- |
Headlamp Control Module | 1 | 1 | 1 | -- |
1. Headlamp Leveling Malfunction | ||||
Circuit/System Description
Battery positive voltage is applied to the headlamp control module at all times. The headlamp control module has a normal operational voltage range of about 12.5-16 V and is only fully functional with the ignition switch is in the RUN position and the headlamp switch in the AUTO position. The communications enable signal from the body control module (BCM) wakes the headlamp control module microprocessor. The headlamp control module receives serial data messages from the engine control module (ECM), transmission control module (TCM), electronic brake control module (EBCM), and BCM with information regarding power mode, speed, steering angle, transmission gear selection, and headlamp switch status. The headlamp control module calculates the headlamp angle and sends commands to the left and right adaptive forward lighting system headlamp actuators. The headlamp actuators drive the headlamps to the position commanded by the headlamp control module. The headlamp control module monitors the headlamp actuator motor control circuits for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected, a DTC will be stored in memory and the driver will be notified with a message displayed over the driver information center located on the instrument cluster.
Conditions for Running the DTC
| • | Battery voltage must be between 9-16 V. |
| • | The ignition is in the ON or RUN position. |
| • | The headlamps are ON. |
Conditions for Setting the DTC
B0984 00 or B0985 00
The DTC will set when the headlamp control module detects no signal and low voltage on the sensor signal line.
Action Taken When the DTC Sets
| • | The headlamp control module disables the headlamp leveling system. |
| • | Headlamp leveling inoperative indication ON. |
| • | Advanced front lighting system fault indication ON. |
Conditions for Clearing the DTC
The condition responsible for setting the DTC no longer exists.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Verify that DTC B3415 is not present.
| ⇒ | If DTC is present, refer to DTC B3415 |
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the appropriate headlamp assembly.
- Test for less than 5 Ω between the ground circuit terminal 8 and ground.
- Ignition ON, connect a test lamp between the ignition circuit terminal 6 and ground. The test lamp should illuminate.
- If all circuits test normal, replace the appropriate headlamp assembly. Verify that the DTC do not reset.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. |
| ⇒ | If the DTC resets, replace the K26 Headlamp Control Module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for headlamp control module replacement, setup, and programming |
