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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 B1992 or B1993 >> Circuit/System Testing

Circuit/System Testing

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DTC B1992

  1. Ignition/vehicle OFF, disconnect the appropriate component:
    • {With T87} E4B Cornering Lamp - Right
    • {Without T87} E4D Daytime Running 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 the appropriate control circuit terminal and ground, ignition on/vehicle in service mode:
    • {With T87} E4B Cornering Lamp - Right = Terminal 6
    • {Without T87} E4D Daytime Running Lamp - Right = Terminal 5
  4. Verify the test lamp turns on and off when commanding the park lamps on and off with the S78 Turn Signal Switch.
    • If the test lamp is always off 
    1. Test control circuit 1203 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 control circuit 1203 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 control circuit 1203 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 appropriate lamp assembly.

DTC B1993

  1. Ignition/vehicle OFF, disconnect the appropriate component:
    • {With T87} E4A Cornering Lamp - Left
    • {Without T87} E4C Daytime Running Lamp - Left
  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 the appropriate control circuit terminal and ground, ignition on/vehicle in service mode:
    • {With T87} E4A Cornering Lamp - Left = Terminal 6
    • {Without T87} E4C Daytime Running Lamp - Left = Terminal 5
  4. Verify the test lamp turns on and off when commanding the park lamps on and off with the S78 Turn Signal Switch.
    • If the test lamp is always off 
    1. Test control circuit 1204 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 control circuit 1204 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 control circuit 1204 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 appropriate lamp assembly.
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