For 1990-2009 cars

### 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 Leveling Control | 1 | 2 | 1 | --
Right Headlamp Leveling Control | 1 | 3 | 1 | --
Left Headlamp Ground | -- | 2 | -- | --
Right Headlamp Ground | -- | 3 | -- | --
1. All Headlamp Leveling Actuator Malfunction 2. Left Headlamp Leveling Actuator Malfunction 3. Right Headlamp Leveling Actuator Malfunction

### Circuit/System Description

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

### Reference Information

#### Schematic Reference

Headlight Leveling 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 leveling 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 appropriate headlamp assembly.
2. Ignition OFF, test for less than 5 Ω between the ground circuit terminal 3 and ground.

⇒ | 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.

⇒ | 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.

⇒ | 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.

⇒ | 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.

⇒ | 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.

⇒ | 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. Connect a test lamp between the control circuit terminal 2 at the appropriate headlamp assembly and ground.
10. Switch the headlamp leveling switch in each position. The test lamp illumination should change in each position.

⇒ | If the test lamp does not illuminate or does not change their illumination, replace the S30 Headlamp 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