Headlamp Leveling Malfunction (Base)
Headlamp Leveling Malfunction (Base)
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.
Diagnostic Fault Information
Circuit/System Description
Each headlamp assembly contains a headlamp leveling motor that is controlled by the headlamp control module. The front and rear suspension position sensors provide the headlamp control module with suspension position information. Each sensor receives a 5-volt reference, signal, and low reference circuits from the headlamp control module. The sensors are connected to the control arms of the front and rear suspension. As the vehicle travels, the suspension compresses and rebounds moving the suspension position sensor arms. This causes the signal output of the sensor to change. The headlamp control module compares the information from both suspension position sensors and adjusts the headlamp leveling as needed. The headlamp control module is wired to each headlamp leveling motor with 4 directional motor control circuits.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference
Component Connector End Views A/C Compressor Clutch
Description and Operation
Exterior Lighting Systems Description and Operation Exterior Lighting Systems
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 Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON, with a scan tool, command the DHL Motor Control Up and Down while observing both headlamps. Both headlamps should operate to the Up and Down positions when commanded.
• If the headlamps do not operate to the Up and Down positions when commanded, refer to Headlamp Leveling Actuator Malfunction.
2. Observe the scan tool Front Leveling Position Sensor voltage parameter. The parameter should be between 0.5 and 4.9 V.
• If the parameter is not within the specified range, refer to Headlamp Leveling Sensor Malfunction.
3. Observe the scan tool Rear Leveling Position Sensor voltage parameter. The parameter should be between 0.5 and 4.9 V.
• If the parameter is not within the specified range, refer to Headlamp Leveling Sensor Malfunction.
Circuit/System Testing
Headlamp Leveling Actuator Malfunction
1. Ignition OFF, disconnect the harness connector at the appropriate headlamp.
2. Remove the AFS 15A fuse.
3. Ignition OFF, scan tool OFF, test for 10-25k ohms between each control circuit terminal listed below and ground.
* Headlamp leveling motor control terminal 1
* Headlamp leveling motor control terminal 2
* Headlamp leveling motor control terminal 3
* Headlamp leveling motor control terminal 4
• If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the headlamp control module.
• If less than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the headlamp control module.
4. Install the AFS 15 A fuse.
5. Ignition ON, scan tool OFF, headlamps ON, verify that a test lamp does not illuminate between each control circuit terminal listed below and ground.
* Headlamp leveling motor control terminal 1
* Headlamp leveling motor control terminal 2
* Headlamp leveling motor control terminal 3
* Headlamp leveling motor control terminal 4
• If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the headlamp control module.
6. If all circuits test normal, replace the headlamp assembly.
Headlamp Leveling Sensor Malfunction
1. Ignition OFF, disconnect the harness connector at the appropriate headlamp leveling sensor.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal C and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the headlamp control module.
3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal A and ground.
• If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the headlamp control module.
• If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the headlamp control module.
4. Verify the scan tool Leveling Position Sensor parameter is less than 0.5 V.
• If greater than the specified range, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the headlamp control module.
5. Install a 3 A fused jumper wire between the signal circuit terminal B and the 5 V reference circuit terminal A. Verify the scan tool Leveling Position Sensor parameter is greater than 4.8 V.
• If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the headlamp control module.
6. If all circuits test normal, test or replace the headlamp leveling sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
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* Headlamp Leveling Front Suspension Height Sensor Replacement Headlamp Leveling Front Suspension Height Sensor Replacement
* Headlamp Leveling Rear Suspension Height Sensor Replacement Headlamp Leveling Rear Suspension Height Sensor Replacement
* Control Module References Control Module References for headlamp control module replacement, setup, and programming