... the car battery. Check all connections between the bulb, ballast, & igniter. Check the vehicle battery terminal.Only one light works, although ... parts.Inspection Procedure: Check all connections between the bulb, ballast, & igniter. Check the bulb that does not work. Check the fuses ... vehicle. If the problem still persists, the Ballast and/or Igniter are bad. If HID system works properly; your vehicle ...