LEMON Manuals: Even more car manuals for everyone
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 >> High Intensity Discharge Lamp Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING:

The high intensity discharge system produces high voltage and current. To reduce the risk of severe shocks and burns:

  • Never open the high intensity discharge system ballast or the arc tube assembly starter.
  • Never probe between the high intensity discharge system ballast output connector and the arc tube assembly.
  1. Ignition OFF, disconnect the headlamp low beam relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
    • If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the B+ circuit terminal 86 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  5. Disconnect the harness connector at the inoperative E4 headlamp.
  6. Test for less than 5 Ω between the headlamp ground circuit terminal 10 and ground
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the E4 headlamp.
  8. Connect a 15 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the headlamp is activated.
    • If the headlamp does not activate and the jumper wire fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the headlamp.
    • If the headlamp does not activate and the jumper wire fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the headlamp.
  9. Connect a test lamp between the B+ circuit terminal 86 and the control circuit terminal 85.
  10. Command the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K9 BCM.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  11. If all circuits test normal, test or replace the headlamp low beam relay.
scientia non olet · About LEMON Manuals