Where do the headlights ground to the chassis?

[Ricochet]

I'm talking about the wires that go from the bulb to the chassis.. When I turn on my headlights my driver's side HID bulb will flick on for a second or two, then off. I thought it was a bad ballast and Dayle was nice enough to send me new ones, but it's doing the same thing still. I've tried four ballasts, two bulbs, and swapped relays on that side - all do the same thing. I'm guessing there is a bad ground, so where can I find it to scrub away with a wire brush?