GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saab 🢒 2008 🢒 9-7x 🢒 Body Systems 🢒 Lighting 🢒 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

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

--

2

--

--

1. Fog Lamp Malfunction

2. Fog Lamp Switch Malfunction

Circuit/System Description

With both the ignition switch in the RUN position and the park lamps or low beam head lamps on, the fog lights will illuminate when the driver presses the fog lamp switch. The FOG LAMP fuse in the engine wiring harness junction block supplies battery positive voltage to the fog lamp relay. With the headlamp switch in either the park or headlamp position and the fog lamp switch is pressed, the body control module (BCM) will energize the fog lamp relay by grounding the control circuit. The current flow is from the fog lamp relay to both front fog lamps and to ground G107 and G103. The state of the fog lamps either ON or OFF will remain the same until the fog lamp switch is pressed again, or the ignition switch is cycled OFF and ON. Fog lamp operation will be cancelled whenever the park lamps are turned OFF or the high beam headlights have been selected.

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

Ignition ON, headlamps ON, verify the scan tool Front Fog Lamp Switch parameter changes between ON and OFF when turning the front fog lamp switch ON and OFF.

⇒If the scan tool parameter does not change between ON and OFF, refer to the Front Fog Lamp Switch Malfunction.
⇒If the switch operates normal, but the front fog lamps do not turn ON and OFF, refer to the Front Fog Lamp Malfunction.

Circuit/System Testing

Front Fog Lamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector X4 at the turn signal/multifunction switch.
  2. Test for less than 5.0 ohms between the ground circuit terminal F and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Front Fog Lamp Switch parameter is OFF.
    4. ⇒If not the specified value, test the signal circuit terminal E 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 E and the ground circuit terminal F. Verify the scan tool Front Fog Lamp Switch parameter is ON.
    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 turn signal/multifunction switch.

Fog Lamp Control Circuit Test

  1. Ignition OFF, disconnect the FOG LAMP relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the fog lamp control circuit terminal 87 and ground.
    3. ⇒If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
    4. ⇒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.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
    5. ⇒If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  5. Disconnect the harness connector at the inoperative fog lamp.
  6. Test for less than 5.0 ohms between the fog lamp ground circuit terminal B and ground.
    7. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the fog lamp.
  8. Connect a 15A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the fog lamps are illuminated.
    9. ⇒If the fog lamps do not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the inoperative fog lamp.
  9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
  10. Headlamps ON turn the front fog lamps ON and OFF. The test lamp should turn ON and OFF when changing between the commanded states.
    11. ⇒If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
    ⇒If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  11. If all circuits test normal, test or replace the FOG LAMP relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Fog Lamp Bulb Replacement
    •  Headlamp Switch Replacement
    •  Control Module References for BCM replacement, programming, and setup