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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1743 (LIGHTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESBACKUP LAMPS MALFUNCTIONCIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6

Circuit/System Testing

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Testing
WARNING: This page is about a different car, the 2009 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the reverse lamp relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the relay controlled output circuit terminal R38 and ground.
    • If the test lamp illuminates, test the relay controlled output circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the relay switch B+ circuit terminal R37 and ground.
    • If the test lamp does not illuminate, test the relay switch 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 relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the reverse lamp relay.
  4. Verify that a test lamp illuminates between the relay coil B+ circuit terminal R36 and ground.
    • If the test lamp does not illuminate, test the relay coil B+ circuit for an open/high resistance.
  5. Disconnect the harness connector at the inoperative backup lamp.
  6. Test for less than 1 ohm between the inoperative backup lamp ground circuit terminal 3 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 backup lamp.
  8. Connect a 10A fused jumper wire between the B+ circuit terminal R37 and the control circuit terminal R38. Verify the backup lamps are illuminated.
    • If the backup lamps do not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the inoperative backup lamp.
  9. Connect a test lamp between the B+ circuit terminal R36 and the control circuit terminal R40.
  10. Command the Backup 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 RIM.
    • 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 RIM.
  11. If all circuits test normal, test or replace the reverse lamp relay.
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
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  • • You are missing required tools, torque specs, or safe lifting equipment.
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