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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 B199A or B199B >> Circuit/System Testing

Circuit/System Testing

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DTC B199A

  1. Ignition/vehicle OFF, exterior lamps OFF, disconnect the E42L Rear Body Structure Stop Lamp - Left.
  2. Verify a test lamp illuminates between ground circuit terminal 6 and B+.
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on the ground circuit or ground connection.
    • Go to next step: If the test lamp illuminates 
  3. Connect a test lamp between control circuit terminal 4 and ground, ignition ON/vehicle in service mode.
  4. Verify the test lamp turns ON and OFF when commanding the Left Rear Turn Signal ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Test circuit 1334 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. Test circuit 1334 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 K219 Lighting Control Module.
    • If the test lamp is always ON 
    1. Test circuit 1334 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found
    2. Replace the K219 Lighting Control Module.
    • Go to next step: If the test lamp turns ON and OFF 
  5. Replace the E42L Rear Body Structure Stop Lamp - Left.

DTC B199B

  1. Ignition/vehicle OFF, exterior lamps OFF, disconnect the E42R Rear Body Structure Stop Lamp - Right.
  2. Verify a test lamp illuminates between ground circuit terminal 1 and B+.
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on the ground circuit or ground connection.
    • Go to next step: If the test lamp illuminates 
  3. Connect a test lamp between control circuit terminal 3 and ground, ignition ON/vehicle in service mode.
  4. Verify the test lamp turns ON and OFF when commanding the Right Rear Turn Signal ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Test circuit 1335 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. Test circuit 1335 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 K219 Lighting Control Module.
    • If the test lamp is always ON 
    1. Test circuit 1335 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found
    2. Replace the K219 Lighting Control Module.
    • Go to next step: If the test lamp turns ON and OFF 
  5. Replace the E42R Rear Body Structure Stop Lamp - Right.
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