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Home >> Buick >> 2018 >> Regal GS >> Repair and Diagnosis >> Accessories & Equipment >> Exterior Lights >> Lighting System - Diagnostic Information And Procedures (B388B-P0504) And Symptoms >> Diagnostic Information and Procedures >> Headlamp Leveling Malfunction (Automatic) >> Circuit/System Verification

Circuit/System Verification

  1. Ignition ON.
  2. Verify the low beam headlamps turn ON and OFF while commanding the low beam headlamps ON and OFF with the headlamp switch.
    • Go to next step: If the low beam headlamps turn ON and OFF 
  3. Verify the scan tool Front Leveling Position Sensor Signal parameter is between 5 % and 90 %.
    • If the parameter is not between 5 % and 90 % 

      Refer to Circuit/System Testing - Headlamp Leveling Sensor Malfunction.

    • Go to next step: If the parameter is between 5 % and 90 % 
  4. Verify the scan tool Rear Leveling Position Sensor Signal parameter is between 5 % and 90 %.
    • If the parameter is not between 5 % and 90 % 

      Refer to Circuit/System Testing - Headlamp Leveling Sensor Malfunction.

    • Go to next step: If the parameter is between 5 % and 90 % 
  5. Verify the left headlamp operates to the UP and DOWN positions when commanding the Left Headlamp Vertical Motor UP and DOWN with a scan tool.
    • If the left headlamp does not operate UP and DOWN 

      Refer to Circuit/System Testing - Headlamp Leveling Actuator Malfunction

    • Go to next step: If the left headlamp operates UP and DOWN 
  6. Verify the right headlamp operates to the UP and DOWN positions when commanding the Right Headlamp Vertical Motor UP and DOWN with a scan tool.
    • If the right headlamp does not operate UP and DOWN 

      Refer to Circuit/System Testing - Headlamp Leveling Actuator Malfunction

    • Go to next step: If the right headlamp operates UP and DOWN 
  7. All OK.