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Home › Chevrolet › 2021 › Traverse L › Repair and Diagnosis › External Pages › Different car › Section 77 (Lighting System - Diagnostic Information And Procedures) › Diagnostic Information and Procedures › DTC B1236 (Lighting Control Module) › Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2020 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, exterior lamps OFF, disconnect the connectors:
    • E5 Backup Lamp
    • A11 Radio - X2
    • {With DD8/DRZ} A10 Inside Rearview Mirror - X1
  2. Connect a test lamp between control circuit terminal 2 and ground circuit terminal 1 at the E5 Backup Lamp connector.
  3. Ignition ON, verify the test lamp turns ON and OFF when commanding the Backup Lamps ON and OFF with a scan tool.
    • If the test lamp is always ON 
    1. Test circuit 24 for a short to voltage
      • If a short to voltage is found, repair the fault.
      • Go to next step: If a short to voltage is not found, replace the K219 Lighting Control Module.
    • If the test lamp is always OFF 
    1. Test circuit 2550 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 24 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. Test circuit 24 for 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
    4. Replace the K219 Lighting Control Module.
    • Go to next step: If the test lamp turns ON and OFF 
  4. Connect following components:
    • A11 Radio - X2
    • {With DD8/DRZ} A10 Inside Rearview Mirror - X1
  5. Verify the test lamp turns ON and OFF when commanding the Backup Lamps ON and OFF with a scan tool.
    • If the test lamp does not turn ON and OFF 
  6. Replace the appropriate component:
    • A11 Radio - X2
    • {With DD8/DRZ} A10 Inside Rearview Mirror - X1
    • Go to next step: If the test lamp turns ON and OFF 
  7. Replace the E5 Backup Lamp.
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