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.

### DTC Descriptors

DTC B2575 02: Left Low Beam Circuit Low Voltage
DTC B2575 05: Left Low Beam Circuit Open or High Voltage
DTC B2699 02: Right Low Beam Circuit Low Voltage
DTC B2699 05: Right Low Beam Circuit Open or High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
LF Low Beam Headlamp Control | B2575 00 | B2575 05 | B2575 05 | --
RF Low Beam Headlamp Control | B2699 00 | B2699 05 | B2699 05 | --
LF Low Beam Headlamp Ground | -- | 1 | -- | --
RF Low Beam Headlamp Ground | -- | 1 | -- | --
1. Headlamps Malfunction

### Circuit/System Description

The headlamp switch is supplied with voltage from the instrument panel cluster (IPC) by two signal circuits, the headlamps signal circuit and the park lamp signal circuit. When the headlamp switch is placed in either the AUTO or HEAD position, the headlamps signal circuit is provided with ground through the switch contacts of the headlamp switch to a common headlamp switch ground back to the IPC. The IPC interprets the flow of voltage and responds by sending a serial data message to the underhood electrical center (UEC) requesting the low beam headlamps be activated. The UEC responds by applying voltage to the left and right low beam headlamp control circuits illuminating the low beam headlamps. Ground for the left headlamp is supplied at G101 and the right headlamp receives ground at G102.

### Conditions for Running the DTC

• | Battery voltage must be between 9-16 volts.

• | Headlamps ON.

### Conditions for Setting the DTC

#### B2575 00

The DTC will set when the UEC detects a short to ground in the left low beam headlamp control circuit when the low beam headlamps are being commanded ON.

#### B2575 05

The DTC will set when the UEC detects a short to voltage or an open/high resistance in the left low beam headlamp control circuit when the low beam headlamps are being commanded ON.

#### B2699 00

The DTC will set when the UEC detects a short to ground in the right low beam headlamp control circuit when the low beam headlamps are being commanded ON.

#### B2699 05

The DTC will set when the UEC detects a short to voltage or an open/high resistance in the right low beam headlamp control circuit when the low beam headlamps are being commanded ON.

### Actions Taken When the DTC Sets

The UEC will disable the headlamp low beam control circuit that has a fault present.

### Conditions for Clearing the DTC

• | The condition responsible for setting the DTC no longer exists.

• | A history DTC will clear once 100 malfunction-free ignition cycles have occurred.

### Reference Information

#### Schematic Reference

Headlights/Daytime Running Lights (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 Testing

1. Ignition OFF, disconnect the harness connector at the inoperative headlamp.
2. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohms between the ground circuit terminal 10 and ground.

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

3. Connect a test lamp between the control circuit terminal 3 and ground.
4. Command the Front Low Beam Test ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the UEC.

⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the UEC.

5. If all circuits test normal, replace the inoperative low beam headlamp.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | High Intensity Discharge Headlamp Ballast Replacement

• | Headlamp Bulb Replacement - Left Side

• | Headlamp Bulb Replacement - Right Side

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