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 Descriptor

DTC B2530 00: Front Fog Light Circuit Low Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Front Fog Lamp Switch Signal | B2740 5a | B2740 05 | B2740 05 | --
Front Fog Lamp Relay Control | B2530 00 | B2530 00 | 1 | --
Front Fog Lamp Control | 1 | 1 | 1 | --
Fog Lamp - LF Ground | -- | 1 | 1 | --
Fog Lamp - RF Ground | -- | 1 | 1 | --
Front Fog Lamp Switch Ground | -- | 2 | 2 | --
1. Front Fog Lamps Malfunction 2. Front Fog Lamp Switch Malfunction

### Circuit/System Description

The front fog lamp switch is supplied with voltage from the instrument panel cluster (IPC) via the front fog lamp switch signal circuit. The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The front fog lamp switch signal circuit is grounded through the switch contacts of the front fog lamp 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). The UEC responds by applying ground to the front fog lamp relay control circuit energizing the front fog lamp relay coil. With the front fog lamp relay coil energized, the relay switch contacts close allowing battery voltage to flow from the front fog lamp fuse to the front fog lamp control circuit which illuminates the front fog lamps. The left front fog lamp receives ground at G101 and the right front fog lamp is grounded at G102.

### Conditions for Running the DTC

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

• | Front fog lamps ON.

### Conditions for Setting the DTC

The DTC will set when the UEC detects a short to ground or an open/high resistance in the front fog lamp relay control circuit.

### Actions Taken When the DTC Sets

When DTC B2530 00 is present, the front fog lamps will not operate when the park lamps are ON and the front fog lamp switch is active.

### Conditions for Clearing the DTC

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

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

### Reference Information

#### Schematic Reference

Fog Lights 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 front fog lamp relay.
2. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
3. Command the Front Fog Light 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, replace the UEC.

⇒ | If the test lamp is always OFF, replace the UEC.

4. If all circuits test normal, test or replace the front fog lamp relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Relay Replacement

• | Underhood Electrical Center or Junction Block Replacement

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