Headlamp Leveling Malfunction

Headlamp Leveling Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The IGN E fuse in the I/P fuse block supplies battery positive voltage to the headlamp leveling switch. When the driver places the headlamp leveling switch in any position, a signal is sent to the headlamp leveling actuators to adjust the headlight aiming to the desired position. The underhood fuse block supplies battery positive voltage and G107 and G103 supplies ground to the headlamp leveling actuators.

Circuit/System Verification

Ignition ON, adjust the headlamp leveling switch from the highest to lowest setting and verify that both headlamp leveling actuators operate.

If one leveling actuator is inoperative, refer to the headlamp leveling actuator circuit test.

If both leveling actuators are inoperative, refer to the headlamp leveling switch circuit test.

Circuit/System Testing

Headlamp Leveling Actuator Circuit Test

1. Ignition OFF, disconnect the harness connector at the affected actuator.
2. Verify that a test lamp illuminates between the ground circuit terminal 1 and ground.

^ If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Ignition ON, verify that a test lamp illuminates between the supply circuit terminal 3 and ground.

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

4. Ignition ON, test for 2.0 - 8.0 volts between the switch signal circuit terminal 2 and ground while operating the leveling switch from the lowest to highest setting.

^ If less than the specified range, test the signal circuit for a short to ground or an open/high resistance.

^ If greater than the specified range, test the signal circuit for a short to voltage.

5. If all circuits test normal, test or replace the affected actuator.

Headlamp Leveling Switch Circuit Test

1. Ignition OFF, disconnect the harness connectors at the headlamp switch.
2. Test for less than 1 ohm of resistance between the low reference circuit terminal X1 C and ground.

^ If greater than the specified range, test the low reference circuit for an open/high resistance.

3. Ignition ON, verify that a test lamp illuminates between the supply circuit terminal X2 G and ground.

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

4. Test the switch signal circuit for an open/high resistance, short to ground, or short to voltage.
5. If all circuits test normal, test or replace the headlamp switch.

Repair Instructions

Perform the after completing the diagnostic procedure.

* Headlamp Replacement (Envoy) Headlamp Replacement (TrailBlazer)
* Headlamp Switch Replacement