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Home >> Hummer >> 2008 >> H3 Base, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 264 (Lighting Systems) >> Diagnostic Information and Procedures >> Front Fog Lamps Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2009 GMC Canyon and 2009 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.

Fog Lamp Malfunction

  1. Ignition OFF, disconnect the fog lamp relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
    • 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.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  5. Ignition OFF, disconnect the harness connector at the inoperative fog lamp.
  6. Test for less than 5.0 ohms between the ground circuit terminal B and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the inoperative 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 activated.
    • If the fog lamps do not activate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the inoperative fog lamp.
  9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
  10. 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.
    • 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.

Fog Lamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
  2. Ignition ON, verify the scan tool front fog lamp switch parameter is Inactive.
    • If not the specified value, test the signal circuit terminal 7 for a short to ground. If the circuit tests normal, replace the BCM.
  3. Install a 3A fused jumper wire between the signal circuit terminal 7 and the low reference circuit terminal 3. Verify the scan tool front fog lamp switch parameter is Active.
    • 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.
  4. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Fog Lamp Indicator Malfunction

  1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
  2. Ignition ON, headlamps ON, connect a test lamp between the indicator control circuit terminal 8 and ground. The test lamp should not be illuminated.
    • If the test lamp is illuminated, test the indicator control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  3. Command the front fog lamps ON with a scan tool. The test lamp should be illuminated.
    • If the test lamp is not illuminated, test the indicator control circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the BCM.
  4. If all the circuits test normal replace the headlamp and panel dimmer switch.
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