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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 B199C or B199D >> Circuit/System Testing

Circuit/System Testing

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DTC B199C

  1. Ignition OFF, exterior lamps OFF, disconnect the connector at the A9A Outside Rearview Mirror - Driver.
  2. Connect a test lamp between control circuit terminal 8 and ground circuit terminal 9.
  3. Ignition ON, verify the test lamp turns ON and OFF when commanding the Left Turn Signal Repeater Lamp Command ON and OFF with a scan tool.
    • If the test lamp is always ON 
    1. Test circuit 2114 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 2150 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 2114 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 2114 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. Replace the E4Y Turn Signal Repeater Lamp - Left.

DTC B199D

  1. Ignition OFF, exterior lamps OFF, disconnect the connector at the A9B Outside Rearview Mirror - Passenger.
  2. Connect a test lamp between control circuit terminal 8 and ground circuit terminal 9.
  3. Ignition ON, verify the test lamp turns ON and OFF when commanding the Right Turn Signal Repeater Lamp Command ON and OFF with a scan tool.
    • If the test lamp is always ON 
    1. Test circuit 2115 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 2250 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 2115 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 2115 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. Replace the E4Z Turn Signal Repeater Lamp - Right.
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