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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 B1919 >> 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. Set the S36 Dimmer Switch to full intensity.
  2. Ignition OFF, disconnect the X5 connector at the K9 Body Control Module, ignition ON:
  3. Verify the appropriate accent/courtesy lamps are not illuminated:
    • E63LR Rear Side Door Inside Handle Illumination Lamp - Left
    • E1LR Rear Side Door Light Conductor Lamp - Left Trim Panel
    • E64LR Rear Side Door Pull Cup Illumination Lamp - Left
    • E63RR Rear Side Door Inside Handle Illumination Lamp - Right
    • E1RR Rear Side Door Light Conductor Lamp - Right Trim Panel
    • E64RR Rear Side Door Pull Cup Illumination Lamp - Right
    • If an accent/courtesy lamp is illuminated 

      Repair the short to voltage on circuit 7557.

    • Go to next step: If all accent/courtesy lamp are not illuminated 
  4. Connect a 3 A fused jumper wire between B+ and circuit terminal 15 at the X5 connector.
  5. Verify the appropriate accent/courtesy lamps are illuminated.
    • If the accent/courtesy lamp is not illuminated and the jumper fuse is OK. 
    1. Test the appropriate circuit for an open/high resistance:
      • E63LR Rear Side Door Inside Handle Illumination Lamp - Left - 2350
      • E1LR Rear Side Door Light Conductor Lamp - Left Trim Panel - 2350
      • E64LR Rear Side Door Pull Cup Illumination Lamp - Left - 2350
      • E63RR Rear Side Door Inside Handle Illumination Lamp - Right - 2350
      • E1RR Rear Side Door Light Conductor Lamp - Right Trim Panel - 2350
      • E64RR Rear Side Door Pull Cup Illumination Lamp - Right - 2450
      • 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 7557 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 appropriate accent/courtesy lamp.
    • If the accent/courtesy lamp is not illuminated and the jumper fuse is open 
    1. Test circuit 7557 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 appropriate accent/courtesy lamp.
    • Go to next step: If the accent/courtesy lamp is illuminated 
  6. Replace the K9 Body Control Module.
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