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Home >> Cadillac >> 2017 >> XT5 Base >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Headlights >> Lighting System - DTC B093F To B3049 >> Diagnostic Information and Procedures >> DTC B3435 or B3440: Headlamp Leveling Control Module Left Servo Driver >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition OFF, disconnect the KR50 Headlamp Relay.
  2. Verify a test lamp illuminates between the B+ circuit terminal 85 and ground.
    • If the test lamp does not illuminate 

      Replace the X50A Fuse Block - Underhood.

    • If the test lamp illuminates 
  3. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate 

      Replace the X50A Fuse Block - Underhood.

    • If the test lamp illuminates 
  4. Connect a test lamp between the control circuit terminal 86 and B+, ignition ON.
  5. Verify the test lamp turns ON and OFF while turning the low beam headlamps ON and OFF with the S78 Turn Signal/Multifunction Switch.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the X5 harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the control circuit terminal and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Ignition OFF.
    4. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the X5 harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the control circuit terminal and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K9 Body Control Module.
    • If the test lamp turns ON and OFF 
  6. Ignition OFF, exterior lamps OFF, connect the KR50 Headlamp Relay.
  7. Ignition OFF, exterior lamps OFF, disconnect the harness connector at the appropriate E13 Headlamp Assembly. It may take up to 2 min for all vehicle systems to power down.
  8. Test for less than 15 Ω between the ground circuit terminal 9 and ground.
    • If 15 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 15 Ω 
  9. Ignition ON.
  10. Verify a test lamp illuminates between the B+ circuit terminal 10 and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the X5 harness connector at the X50A Fuse Block - Underhood.
    2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the KR50 Headlamp Relay.
    • If the test lamp illuminates 
  11. Test or replace the K28 Headlamp Leveling Control Module.
  12. Ignition ON.
  13. Verify the appropriate headlamp operates to the UP and DOWN positions when commanding the appropriate Headlamp Vertical Motor UP and DOWN with a scan tool.
    • If the headlamp does not operate UP and DOWN 
    • Test or replace the E13 Headlamp Assembly.
    • If the headlamp operates UP and DOWN 
  14. All OK.
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