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

Fog Lamp Relay Control

B2530 02

B2530 05

B2530 05

--

Fog Lamp Voltage Supply

1

1

1

--

Front Fog Lamp Switch Signal

1

1

--

--

Fog Lamp Relay Ground

--

1

--

--

Fog Lamp - LF Ground

--

1

--

--

Fog Lamp - RF Ground

--

1

--

--

Fog Lamp Switch Ground

--

1

--

--

1. Front Fog Lamps Malfunction

Circuit/System Description

When the fog lamp switch is placed in the ON position, ground is applied through the fog lamp switch signal circuit at G300 to the body control module (BCM). The BCM applies battery voltage through the fog lamp relay control circuit to the coil side of the fog lamp relay and the fog lamps ON indicator located on the fog lamp switch. Battery voltage is applied at all times from the FOG LP fuse to the switch side of the fog lamp relay. When the relay coil is energized, the relay switch contacts close and allow battery voltage to be applied from the FOG LP fuse, through the relay switch contacts, to the fog lamps. Ground for the fog lamps is applied at all times at G101 for the left fog lamp and G102 for the right fog lamp. G102 also serves as ground for the coil side of the fog lamp relay.

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

    • DTC B2530 02 will set when the BCM detects a short to ground in the front fog lamp relay control circuit.
    • DTC B2530 05 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.
    • You issue a scan tool CLEAR DTCs command.
    • 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

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 Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Testing

  1. Ignition OFF, disconnect the front fog lamp relay.
  2. Test for less than 1.0 ohm of resistance between the fog lamp relay ground circuit and ground at the relay terminal.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Connect a test lamp between the front fog lamp relay control circuit and the ground circuit at the relay terminals.
  5. Command the front fog lamps ON and OFF with a scan tool. 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.

    •  Underhood Electrical Center or Junction Block Replacement
    •  Relay Replacement
    •  Control Module References for BCM replacement, setup, and programming