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
--- | --- | --- | --- | ---
High Beam Indicator Supply Circuit | 1 | 1 | -- | --
High Beam Indicator Ground Circuit | -- | 1 | 1 | --
1. High Beam Indicator Inoperative

### Circuit/System Description

The headlamp may be turned on 2 different ways. First, when the driver places the headlamp switch in the ON position, for manual operation. Second, with the headlamp switch placed in the OFF position activating automatic lamp control (ALC). The Left High Beam, Right High Beam, Left Low Beam, and Right Low Beam fuses in the fuse block - underhood, supply battery positive voltage to both low and high beam lamps at all times. For manual operation, when the headlamp switch is in the ON position, the headlamp switch supplies ground directly to the headlamps and to the body control module (BCM) on the headlamp low or high beam signal circuit, depending on the position of the headlamp dimmer switch. The BCM uses this signal to determines if the conditions are present to illuminate the daytime running lamps or park lamps.

### Diagnostic Aids

• | An open in the BCM would cause the high beam indicator to be inoperative

• | An open/high resistance, short to voltage or short to ground in the instrument cluster would cause the high beam indicator to be inoperative.

### Reference Information

#### Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

#### Connector End View Reference

Lighting Systems Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

• | Scan Tool Data Definitions

• | Scan Tool Data List

• | Scan Tool Output Controls

### Circuit/System Verification

Ignition ON, turn ON and OFF the high beam headlamps. The high beam indicator should turn ON and OFF with the high beam headlamps.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the instrument panel cluster.
2. Ignition OFF, test for less than 1 ohm of resistance between the ground circuit and ground.

⇒ | If greater than 1 ohm, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit and the ground circuit.
4. Turn the high beam headlamps ON and OFF. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | If the test lamp remains ON all the time, test for a short to voltage on the control circuit. If the circuit tests normal, replace the BCM.

⇒ | If the test lamp remains OFF all the time, test for a short to ground or an open/high resistance on the control circuit. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, test or replace the instrument panel cluster.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the instrument panel cluster.
2. Test for 5-15 ohms of resistance between the control terminal and the ground terminal of the instrument panel cluster.

⇒ | If the resistance is not within the specified range, replace the instrument panel cluster.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Control Module References for BCM replacement, setup, and programming

• | Instrument Cluster Replacement