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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 >> DTC B3806: High Beam and Headlamp Flash Select >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, disconnect the harness connector at the S78 turn signal/multifunction switch. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 15Ω between the ground circuit terminal 3 and ground.
    • If 15Ω 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 15Ω 
  3. Ignition ON.
  4. Verify the scan tool Headlamps Flash Switch parameter is Inactive.
    • If not Inactive 
    1. Ignition OFF, disconnect the X3 harness connector at the K9 body control module.
    2. Test for infinite resistance between the signal circuit terminal 4 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 Inactive 
  5. Install a 3A fused jumper wire between the signal circuit terminal 4 and the ground circuit terminal 3.
  6. Verify the scan tool Headlamps Flash Switch parameter is Active.
    • If not Active 
    1. Ignition OFF, disconnect the X3 harness connector at the K9 body control module, ignition ON.
    2. Test for less than 1V between the signal circuit terminal 4 and ground.
      • If 1V or greater, repair the short to voltage on the circuit.
      • If less than 1V
    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 K9 body control module.
    • If Active 
  7. Test or replace the S78 turn signal/multifunction switch.
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