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 has overviews of all diagnostic categories.

DTC Descriptors

DTC B1461 00

Left Headlamp Horizontal Motor Circuit Malfunction

DTC B1462 00

Right Headlamp Horizontal Motor Circuit Malfunction

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ignition Left Headlamp	1	1	-	B1461 00
Ignition Right Headlamp	2	2	-	B1462 00
Left Headlamp Ground	-	1	-	B1461 00
Right Headlamp Ground	-	2	-	B1462 00
1. Left Headlamp Leveling Malfunction 2. Right 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 AUTOMATIC LIGHT 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, transmission control module, electronic brake control module, 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

B1461 00 or B1462 00

The DTC will set when the headlamp control module detects a short to voltage or an open/high resistance on any of the headlamp actuator control circuits.

Action Taken When the DTC Sets

•	When DTC B1461 or DTC B1462 sets, the headlamp control module will attempt to return the lamps to a nominal position and disable all requests to both headlamp actuators.

•	The driver information center will display adaptive forward lighting Lamps Need Service.

•	On vehicles equipped with both adaptive forward lighting and headlamp leveling, the headlamp leveling system will be disabled.

Conditions for Clearing the DTC

A DTC becomes history, when the condition responsible for setting the DTC no longer exists for more than 3 s.

Reference Information

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Control Module References for information on diagnostic tools

Circuit/System Testing

1.	Ignition OFF, disconnect the harness connector at the appropriate headlamp assembly.

2.	Test for less than 5 Ω between the ground circuit terminal 1, 8 and ground.

3.	If greater than the specified range, test the ground circuit for an open/high resistance.

4.	Ignition ON, headlamps ON, connect a test lamp between the ignition circuit terminal 6 and ground. The test lamp should turn ON.

5.	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

6.	If all circuits test normal, replace the appropriate headlamp assembly. Verify that the DTC do not reset.

7.	If the DTC resets, replace the K26 Headlamp Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Headlamp Replacement

•	Control Module References for headlamp control module replacement, setup, and programming