Diagnostic Instructions
DTC Descriptors
DTC B1461 00: Left Headlamp Horizontal Motor Circuit No Additional Information
DTC B1461 02: Left Headlamp Horizontal Motor Circuit Short to Ground
DTC B1461 39: Left Headlamp Horizontal Motor Circuit Internal Electronic Failure
DTC B1461 54: Left Headlamp Horizontal Motor Circuit Temperature High
Circuit/System Description
Battery positive voltage is applied to the headlamp control module at all times and when the ignition switch is in the RUN and CRANK positions. The headlamp control module has an operational voltage range of about 10.5-16 volts and is only
fully functional when the ignition switch is in the RUN position. The voltage input from the ignition switch wakes the headlamp control module microprocessor. The headlamp control module receives serial data messages via GMLAN from the engine control module
(ECM), transmission control module (TCM), electronic brake control module (EBCM), and body control module (BCM) with regards to 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 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 (DIC) located on the instrument panel
cluster (IPC). For more detailed information concerning exterior lighting operation, refer to
Exterior Lighting Systems Description and Operation
.
Conditions for Running the DTC
The headlamp control module performs this diagnostic test mode every 250 milliseconds when the following conditions are met:
| • | Battery voltage must be between 10-16 volts. |
| • | Ignition is in the RUN position. |
| • | Headlamp switch is in the AUTO position. |
| • | High or low beam headlamps must be active. |
| • | Vehicle speed greater than 2 mph. |
| • | Transmission is in the DRIVE position. |
Conditions for Setting the DTC
DTC B1461 00
This DTC will set when the headlamp control module detects an open or short to voltage in the left headlamp actuator control circuits.
DTC B1461 02
This DTC will set when the headlamp control module detects a short to ground in the left headlamp actuator control circuits.
DTC B1461 39
This DTC will set when the headlamp control module detects an internal circuit failure.
DTC B1461 54
This DTC will set when the headlamp control module detects a high temperature condition in the left headlamp actuator control circuits.
Actions Taken When the DTC Sets
| • | When DTC B1461 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 (DIC) will display Service AFS Lamps. |
| • | On vehicles equipped with both AFL and headlamp leveling, the headlamp leveling system will be disabled. |
Conditions for Clearing the DTC
| • | The condition responsible for setting the DTC no longer exists. |
| • | You issue a scan tool CLEAR DTCs command. |
| • | A history DTC will clear once 40 consecutive malfunction-free ignition cycles have occurred. |
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference
Lighting Systems Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
DTC B1461 00
- Ignition OFF, disconnect the headlamp control module harness connector.
- Ignition ON, verify that a test lamp does not illuminate between ground and each LH AFS motor control circuit one at a time.
| ⇒ | If the test lamp illuminates, repair the effected LH AFS motor control circuit for a short to voltage. |
- Ignition OFF, test each LH AFS motor control circuit for good continuity.
| ⇒ | If good continuity is not detected, repair the affected LH AFS motor control circuit for shorts to each other, or an open/high resistance. If the circuits test normal, test or replace the LH AFS motor. |
- If all circuits test normal, replace the headlamp control module.
DTC B1461 02
- Ignition OFF, disconnect the headlamp control module harness connector.
- Verify that a test lamp does not illuminate between battery positive voltage and each LH AFS motor control circuit one at a time.
| ⇒ | If the test lamp illuminates, repair the effected LH AFS motor control circuit for a short to ground. If the circuits test normal, test or replace the LH AFS motor. |
- If all circuits test normal, replace the headlamp control module.
DTC B1461 39
- Ignition ON, install a scan tool and clear all DTCs.
- Operate the vehicle within the conditions for running the DTC.
- With the scan tool, retrieve DTCs and determine if DTC B1461 39 has reset as current.
| ⇒ | If DTC B1461 39 resets as a current DTC, replace the headlamp control module. |
DTC B1461 54
- Ignition ON, install a scan tool and clear all DTCs.
- Operate the vehicle within the conditions for running the DTC.
- With the scan tool, retrieve DTCs and determine if DTC B1461 54 has reset as current.
| ⇒ | If DTC B1461 54 resets as a current DTC, replace the headlamp control module. |
Repair Instructions
Always perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
