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HOMESERVICE MANUALSCHEVROLET2009TAHOE BASE, 4.8 CREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 212 (LIGHTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESFRONT FOG LAMPS MALFUNCTIONCIRCUIT/SYSTEM TESTING
2009 Chevrolet Tahoe Base, 4.8 C

Circuit/System Testing

2009 Chevrolet Tahoe Base, 4.8 CSECTION Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2010 GMC Yukon XL, 2010 GMC Yukon, 2010 Chevrolet Tahoe, 2010 Chevrolet Suburban, and 2010 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Front Fog Lamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
  2. Ignition OFF, verify a test lamp illuminates between B+ and the ground circuit terminal 8.
    • 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.
    • If not the specified value, test the signal circuit terminal 10 for a short to ground. If the circuit tests normal, replace the BCM.
  4. Install a 3 A fused jumper wire between the signal circuit terminal 10 and the ground circuit terminal 8. 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.
  5. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Front Fog Lamps Malfunction

  1. Ignition OFF, disconnect the front fog lamp relay.
  2. Ignition ON, verify 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 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 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. Disconnect the harness connector at the appropriate front fog lamp.
  6. Ignition OFF, test for less than 5.0 Ξ© 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 front fog lamp.
  8. Connect a 15 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the front fog lamps are activated.
    • If the front 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 front fog lamp.
  9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
  10. Ignition ON, 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 open/high resistance. If the circuit tests normal, replace the BCM.
  11. If all circuits test normal, test or replace the front fog lamp relay.
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