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Headlamp Levelling Malfunction

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 provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Ignition Headlamp Switch

1

1

--

--

Ignition Left Headlamp

1

2

--

--

Ignition Right Headlamp

1

3

--

--

Left Headlamp Levelling Control

1

2

1

--

Right Headlamp Levelling Control

1

3

1

--

Left Headlamp Ground

--

2

--

--

Right Headlamp Ground

--

3

--

--

1. All Headlamp Levelling Actuator Malfunction

2. Left Headlamp Levelling Actuator Malfunction

3. Right Headlamp Levelling Actuator Malfunction

Circuit/System Description

Each headlamp assembly contains a headlamp levelling motor that is controlled by the headlamp switch. The headlamp switch is a resistance ladder switch and wired to each headlamp levelling motor. With the ignition in ON position the headlamp switch and each headlamp levelling motor is applied to B+. Each headlamp levelling motor is permanently grounded.

Reference Information

Schematic Reference

Headlamps/Daytime Running Lamps (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 scan tool information

Circuit/System Verification

Ignition ON, cycle the headlamp levelling switch in each position while observing both headlamps. Both headlamps should operate to the appropriate position when commanded.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the headlight assembly listed below.
    2. ⇒M29L Headlight Levelling Actuator - Left
    ⇒M29R Headlight Levelling Actuator - Right
  2. Ignition OFF, test for less than 5 Ω between the ground circuit terminal 3 and ground.
    3. ⇒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 1 and ground. The test lamp should illuminate.
    4. ⇒If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  4. Ignition OFF, disconnect the harness connector at the S30 Headlamp Switch.
  5. Ignition ON, connect a test lamp between the ignition circuit terminal 9 and ground. The test lamp should illuminate.
    6. ⇒If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  6. Ignition ON, test for less than 0.3 V between the signal circuit terminal 10 and ground.
    7. ⇒If greater than the specified range, test the signal circuit for a short to voltage.
  7. Ignition OFF, test for greater than 500 kΩ between the signal circuit terminal 10 and ground.
    8. ⇒If less than the specified range, test the signal circuit for a short to ground.
  8. Ignition OFF, test for less than 5 Ω between the signal circuit terminal 10 at the S30 Headlamp Switch and the control circuit terminal 2 at the appropriate headlamp assembly.
    9. ⇒If greater than the specified range, test the signal circuit for an open/high resistance.
  9. Ignition OFF, reconnect the harness connector at the S30 Headlamp Switch.
  10. Ignition ON, test for 4.5-11.5 V between the control circuit terminal 8 at the appropriate headlamp assembly and ground. Switch the headlamp leveling switch in each position, the voltage should change in each position.
    11. ⇒If the voltage does not change, replace the S30 Headlight Switch.
  11. If all circuits test normal, replace the appropriate headlamp assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Headlamp Switch Replacement
    •  Headlamp Replacement
   


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