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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 B19A3 or B19A4 >> 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.

DTC B19A3

  1. Ignition OFF, exterior lamps OFF, disconnect the X110 connector at the E13LA Front Headlamp - Left.
  2. Connect a test lamp between ground circuit terminal 1 and control circuit terminal 6.
  3. Ignition ON, verify the test lamp turns ON and OFF when commanding the Left Daytime Running Lamp ON and OFF with a scan tool.
    • If the test lamp is always ON 
    1. Test circuit 7538 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 turns is always OFF 
    1. Test circuit 550 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 7538 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 7538 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
    4. Replace the K219 Lighting Control Module.
    • Go to next step: If the test lamp turns ON and OFF 
  4. Replace the E13LA Front Headlamp - Left.

DTC B19A4

  1. Ignition OFF, exterior lamps OFF, disconnect the X120 connector at the E13RA Front Headlamp - Right.
  2. Connect a test lamp between ground circuit terminal 1 and control circuit terminal 6.
  3. Ignition ON, verify the test lamp turns ON and OFF when commanding the Right Daytime Running Lamp ON and OFF with a scan tool.
    • If the test lamp is always ON 
    1. Test circuit 7539 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 650 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 7539 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 7539 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
    4. Replace the K219 Lighting Control Module.
    • Go to next step: If the test lamp turns ON and OFF 
  4. Replace the E13RA Front Headlamp - Right.
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