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Home >> Buick >> 2015 >> Regal GS, AWD >> Repair and Diagnosis >> Accessories & Equipment >> Interior/Illumination Lights >> Lighting System - Diagnostic Information And Procedures >> Diagnostic Information and Procedures >> Headlamp Leveling Malfunction (Automatic) >> Circuit/System Testing

Circuit/System Testing

Headlamp Leveling Actuator Malfunction

  1. Ignition OFF, exterior lamps OFF, disconnect the harness connector at the appropriate E13 Headlamp Assembly.
  2. Test for less than 5Ω between the appropriate ground circuit terminal listed below and ground.
    • E13LA Headlamp Assembly - left terminal 8 with A1LL
    • E13RA Headlamp Assembly - right terminal 8 with A1LL
    • E13LA Headlamp Assembly - left terminal 7 with A1SL
    • E13RA Headlamp Assembly - right terminal 7 with A1SL
    • If 5Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2Ω in the ground circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, repair the open/high resistance in the ground connection.
    • If less than 5Ω 
  3. Ignition ON.
  4. Verify a test lamp illuminates between the appropriate B+ circuit terminal listed below and ground.
    • E13LA Headlamp Assembly - left terminal 6 with A1LL
    • E13RA Headlamp Assembly - right terminal 6 with A1LL
    • E13LA Headlamp Assembly - left terminal 8 with A1SL
    • E13RA Headlamp Assembly - right terminal 8 with A1SL
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the X2 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 2Ω in the control circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, replace the X50A Fuse Block - Underhood.
    • If the test lamp illuminates 
  5. Test or replace the K26 Headlamp Control Module.
  6. Ignition ON.
  7. Verify the appropriate headlamp operates to the UP and DOWN positions when commanding the DHL Motor Control UP and DOWN with a scan tool.
    • If the appropriate headlamp does not operate UP and DOWN, test or replace the appropriate headlamp assembly.

Headlamp Leveling Sensor Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate B51 Suspension Height Sensor, ignition ON.
  2. Verify a test lamp illuminates between the low reference circuit terminal 2 and B+.
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the harness connector at the K26 Headlamp Control Module.
    2. Test for less than 2Ω in the low reference circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, replace the K26 Headlamp Control Module.
    • If the test lamp illuminates 
  3. Ignition ON.
  4. Test for 4.8-5.2V between the 5V reference circuit terminal 1 and ground.
    • If less than 4.8V 
    1. Ignition OFF, disconnect the harness connector at the K26 Headlamp Control Module.
    2. Test for infinite resistance between the 5V reference circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2Ω in the 5V reference circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, replace the K26 Headlamp Control Module.
    • If greater than 5.2V 
    1. Ignition OFF, disconnect the harness connector at the K26 Headlamp Control Module, ignition ON.
    2. Test for less than 1V between the 5V reference circuit and ground.
      • If 1V or greater, repair the short to voltage on the circuit.
      • If less than 1V, replace the K26 Headlamp Control Module.
    • If between 4.8-5.2V 
  5. Verify the appropriate scan tool Leveling Position Sensor parameter is less than 1V.
    • If 1V or greater 
    1. Ignition OFF, disconnect the harness connector at the K26 Headlamp Control Module, ignition ON.
    2. Test for less than 1V between the signal circuit terminal 3 and ground.
      • If 1V or greater, repair the short to voltage on the circuit.
      • If less than 1V, replace the K26 Headlamp Control Module.
    • If less than 1V 
  6. Install a 3A fused jumper wire between the 5-volt reference circuit terminal 1 and the signal circuit terminal 3.
  7. Engine RUNNING, verify the appropriate scan tool Leveling Position Sensor parameter is greater than 4.8V.
    • If less than 4.8V 
    1. Ignition OFF, disconnect the harness connector at the K26 Headlamp Control Module.
    2. Test for infinite resistance between the signal circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2Ω in the signal circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, replace the K26 Headlamp Control Module.
    • If 4.8V or greater 
  8. Test or replace the appropriate B51 Suspension Height Sensor.
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