Casutherland42 wrote:wiring harness pretty good? What exactly does it do?
Why do I need a relay harness?
Some vehicles might be able to power up HID systems normally without problems at install time. It will probably not last long. The inrush load can be up to max 13 amps per ballast, compared to 7amps inrush when using halogen. The factory design parameters for headlight circuits are 7 amps inrush and 4.5 amps continuous load. So over time, connectors, multifunction switch, headlight switch, wiring and fuse holders will slowly degrade, because of heat buildup. These components are very time consuming to troubleshoot because they are usually well hidden behind dashboards and other wiring looms. Parts can cost several hundred dollars and add 8h labor to that and it becomes obvious that a $18 to $25 wiring harness is a cheap insurance.