hid's can put a lot of strain on the wiring harness when powering up. Using the harness wires the lights/ballasts directly to the battery for power removing this strain. Then you run a set of wires to the headlight harness so when you turn on your lights, the relay tells the hid's to turn on.guppie said:Does the Phillips kit require no drilling?
What about a relay? What's the purpose of those. I see some kits come with one some you buy seperate?