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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Cobalt 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Front Fog Lamps Malfunction

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.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Fog Lamp Relay B+

1

1

--

--

Fog Lamp Switch Signal

2

2

2

--

Fog Lamp Relay Control

B2530 02

B2530 05

B2530 05

--

Fog Lamp Control

1

1

1

--

Fog Lamp - LF Ground

--

1

--

--

Fog Lamp - RF Ground

--

1

--

--

Fog Lamp Relay Ground

--

1

--

--

Fog Lamp Switch Ground

--

2

--

--

1. Fog Lamps Malfunction

2. Fog Lamp Switch Malfunction

Circuit/System Description

The fog lamp relay is supplied with battery voltage at all times. The fog lamp switch signal circuit is grounded momentarily by pressing the fog lamp switch. The body control module (BCM) energizes the fog lamp relay by applying voltage to the fog lamp relay control circuit. When the fog lamp relay is energized, the relay switch contacts close and battery voltage is applied through the FOG LAMP fuse to the fog lamp control circuit which illuminates the fog lamps.

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 Verification
  1. Ignition ON, observe the scan tool Front Fog Lamp Switch parameter while activating the front fog lamp switch. The parameter should change between Active and Inactive.
    2. ⇒If the parameter does not change between the commanded states, refer to Fog Lamp Switch Malfunction.
  2. Activate the front fog lamp switch and observe the fog lamps. The fog lamps should illuminate.
    3. ⇒If the front fog lamps do not illuminate, refer to Fog Lamps Malfunction.

Circuit/System Testing

Fog Lamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the fog lamp switch.
  2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal A.
    3. ⇒If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Front Fog Lamp Switch parameter is Inactive.
    4. ⇒If not the specified value, test the signal circuit terminal C for a short to ground. If the circuit tests normal, replace the BCM.
  4. Install a 3A fused jumper wire between the signal circuit terminal C and ground. Verify the scan tool Front Fog Lamp Switch parameter is Active.
    5. ⇒If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the fog lamp switch.

Fog Lamps Malfunction

  1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
  2. Connect a test lamp between the control circuit terminal C3 and ground.
  3. Command the Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    4. ⇒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 an open/high resistance. If the circuit tests normal, replace the BCM.
  4. Ignition OFF, connect the X2 harness connector at the underhood fuse block.
  5. Disconnect the X3 harness connector at the underhood fuse block.
  6. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal F2 and ground.
    7. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect the X3 harness connector at the underhood fuse block.
  8. Disconnect the harness connector at the inoperative fog lamp.
  9. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal B and ground.
    10. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  10. Connect a test lamp between the control circuit terminal A and ground.
  11. Command the Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    12. ⇒If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.
    ⇒If the test lamp is always OFF and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
    ⇒If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, replace the underhood fuse block.
  12. If all circuits test normal, replace the inoperative fog lamp.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Fog Lamp Switch Replacement
    •  Front Fog Lamp Replacement
    •  Underhood Electrical Center or Junction Block Bracket Replacement
    •  Control Module References for BCM replacement, setup, and programming