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Home >> Cadillac >> 2007 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 1138 (Lighting Systems) >> Diagnostic Information and Procedures >> DTC B2545 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the inside rearview mirror.
  2. Connect a test lamp between the inside rearview mirror backup lamp supply voltage circuit terminal 9 and ground.
  3. 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 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, test the BCM 4 fuse voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. Connect the harness connector at the inside rearview mirror.
  5. Ignition OFF, disconnect the harness connector at the inoperative backup lamp.
  6. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohms between the inoperative backup lamp ground circuit terminal and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect a test lamp between the backup lamp supply voltage circuit terminal E and ground.
  8. 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 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.
  9. If all circuits test normal, test or replace the inoperative backup lamp.
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