GM Service Manual Online
For 1990-2009 cars only

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 B2530 02: Front Fog Lamps Control Circuit Short to Ground

DTC B2530 05: Front Fog Lamps Control Circuit Open or Short to Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Front Fog Lamp Switch Signal

1

1

--

--

Front Fog Lamp Relay Control

B2530 02

B2530 05

B2530 05

--

Front Fog Lamp Control

1

1

1

--

Front Fog Lamp Relay Ground

--

1

1

--

Fog Lamp - LF Ground

--

1

1

--

Fog Lamp - RF Ground

--

1

1

--

Fog Lamp Switch Ground

--

1

1

--

1. Front Fog Lamps Malfunction

Circuit/System Description

The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The body control module (BCM) energizes the front fog lamp relay by applying battery voltage to the front fog lamp relay control circuit. When the front fog lamp relay is energized, battery voltage is applied via the FOG LAMP fuse to the front fog lamp supply voltage circuit which illuminates the front fog lamps.

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

B2530 02

This DTC will set when the BCM detects a short to ground in the front fog lamp relay control circuit.

B2530 05

This DTC will set when the BCM detects an open or short to voltage in the front fog lamp relay control circuit.

Actions Taken When the DTC Sets

    • When DTC B2530 02 is present, the front fog lamps will not operate when the park lamps are ON and the front fog lamp switch is active.
    • When DTC B2530 05 is present, the front fog lamps and/or the front fog lamp indicator will be ON at all times or will not operate.

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. Ignition OFF, scan tool OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal C3 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Connect a test lamp between the control circuit terminal A4 and ground.
  5. Command the front fog lamps ON and OFF with the front fog lamp switch. The test lamp should turn ON and OFF when changing between the commanded states.
  6. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
    If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the BCM.
  7. 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 BCM replacement, setup, and programming