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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 224 (Lighting System - Diagnostic Information And Procedures (1 Of 2)) >> Diagnostic Information and Procedures >> DTC B1143 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the X7 connector at the K9 Body Control Module, Ignition ON.
  2. Verify the E8S Rear Compartment Courtesy Lamp is not illuminated.
    • If the E8S Rear Compartment Courtesy Lamp is illuminated 

      Repair the short to voltage on circuit 737.

    • Go to next step: If the E8S Rear Compartment Courtesy Lamp is not illuminated 
  3. Connect a 3 A fused jumper wire between B+ and terminal 18 at the X7 connector.
  4. Verify the E8S Rear Compartment Courtesy Lamp is illuminated.
    • If the E8S Rear Compartment Courtesy Lamp is not illuminated and the jumper fuse is OK. 
    1. Test circuit 2450 for an open/high resistance:
      • If an open/high resistance is found, repair the fault on the circuit or ground connection.
      • Go to next step: If an open/high resistance is not found.
    2. Test circuit 737 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit
      • Go to next step: If an open/high resistance is not found
    3. Replace the E8S Rear Compartment Courtesy Lamp.
    • If the E8S Rear Compartment Courtesy Lamp is not illuminated and the jumper fuse is open 
    1. Test circuit 737 for a short to ground.
      • If a short to ground is found, repair the fault on the circuit
      • Go to next step: If a short to ground is not found
    2. Replace the E8S Rear Compartment Courtesy Lamp.
    • Go to next step: If the E8S Rear Compartment Courtesy Lamp is illuminated 
  5. Replace the K9 Body Control Module.
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