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 Descriptor

DTC B2530 00: Front Fog Lamps Control Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Front Fog Lamp Relay B+

B2530 00

B2530 00

--

--

Front Fog Lamp Control

1

1

1

--

Front Fog Lamp Switch Signal

B2527 00

2

2

--

Front Fog Lamp Relay and Indicator Control

B2530 00

B2530 00

B2530 00

--

Front Fog Lamp Ground

--

1

--

--

Headlamp Switch Ground

--

4

--

--

1. Fog Lamp Malfunction

2. Fog Lamp Switch Malfunction

Circuit/System Description

The front fog lamp relay coil is supplied with battery voltage when the ignition is in the RUN or CRANK position. The front fog lamp relay switch is supplied with battery voltage at all times. 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 ground to the front fog lamp relay control circuit. When the front fog lamp relay is energized, the relay switch contacts close and battery voltage is applied through the FRONT FOG fuse to the front fog lamp control circuit which illuminates the front fog lamps.

Conditions for Running the DTC

The battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

    • When the BCM receives a front fog lamp switch OFF command and the front fog lamp relay control circuit is shorted to ground or has an open/high resistance.
    • When the BCM receives a front fog lamp switch ON command and the front fog lamp relay control circuit is shorted to voltage.

Action Taken When the DTC Sets

The front fog lamps will be inoperative or always ON.

Conditions for Clearing the DTC

    • This DTC will clear on current status after the condition for setting the fault is corrected.
    • A history DTC will clear after 100 consecutive ignition cycles without a fault present.

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 ON, verify that a test lamp does not illuminate between the front fog lamp control circuit terminal 87 and ground.
  3. If the test lamp illuminates, test the control circuit for a short to voltage.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
  5. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground.
  6. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
  7. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  8. Disconnect the harness connector at the inoperative front fog lamp.
  9. Test for less than 5.0 ohms between the front fog lamp ground circuit terminal B and ground.
  10. If greater than the specified range, test the ground circuit for an open/high resistance.
  11. Connect a test lamp between the control circuit terminal A and ground.
  12. Ignition OFF, connect a 15A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the test lamp illuminates.
  13. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance.
    If the test lamp is always ON, test the control circuit for a short to voltage.
  14. If all circuits test normal, replace the front fog lamp relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, programming, and setup.