B0984
DTC B0984 or B0985
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC B0984 00
- Left Headlamp Light Distribution Shutter Control Circuit Malfunction
DTC B0985 00
- Right Headlamp Light Distribution Shutter Control Circuit Malfunction
Diagnostic Fault Information
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
Headlights/Daytime Running Lights (DRL) Schematics (Headlights/Daytime Running Lights (DRL) Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Verify that DTC B3415 is not present.
If DTC is present, refer to DTC B3415 (B3415).
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the appropriate headlamp assembly.
2. Test for less than 5 ohm between the ground circuit terminal H and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, connect a test lamp between the ignition circuit terminal B and ground. The test lamp should illuminate.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
4. If all circuits test normal, replace the appropriate headlamp assembly. Verify that the DTC do not reset.
• If the DTC resets, replace the K26 Headlamp Control Module.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Headlamp Replacement (Headlamp Replacement)
* Control Module References (Programming and Relearning) for headlamp control module replacement, setup, and programming