LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 2007 >> STS Base, 4.6 A, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 12 (Lighting Systems) >> Diagnostic Information and Procedures >> DTC B2545 >> Circuit/System Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Circuit/System Testing

WARNING: This page is about a different car, the 2008 Cadillac SRX. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the joint connector at the left rear fuse block.
  2. Connect a test lamp between the backup lamp supply voltage circuit terminal S17 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. Disconnect the harness connector at the inside rearview mirror.
  5. Verify that a test lamp does not illuminate between the inside rearview mirror backup lamp supply voltage circuit terminal 9 and B+.
    • If the test lamp illuminates, test the control circuit for a short to ground.
  6. Connect the harness connector at the inside rearview mirror.
  7. Ignition ON, verify that a test lamp illuminates between the inside rearview mirror backup lamp supply voltage circuit terminal S15 and B+.
    • If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the inside rearview mirror.
  8. Disconnect the harness connector at the inoperative backup lamp.
  9. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohms of resistance between the inoperative backup lamp ground circuit terminal B and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  10. Ignition ON, verify that a test lamp does not illuminate between the backup lamp supply voltage circuit terminal S16 and ground.
    • If the test lamp illuminates, test the backup lamp control circuit for a short to voltage.
  11. Connect the harness connector at the inoperative backup lamp.
  12. Connect a 10-A fused jumper wire between the backup lamp supply voltage circuit terminal S16 and B+. Verify the backup lamps are activated.
    • If the backup lamps do not activate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the inoperative backup lamp.
  13. If all circuits test normal, test or replace the left rear fuse block.
scientia non olet · About LEMON Manuals