how do i know if i need a new ballast or new ignitor?
bulbs are new.

 

anybody know???

 

what exactly is the problem? is the HID not firing up?

it it isnt, it could be anything. bad ballast. a short circuit. burnt wire. new bulb was incorrectly installed/new bulb was faulty.

 

One light not working, or both? If one works you can use the parts from that side to test each of the elements on the bad side. If it's both you've got a problem higher up the chain, unless you installed those 12-buck Chinese jobs off E-Bay and they've fried your system on both sides.