the front right head lamp electronics does not get voltage -- needs replacement on 1999 Audi A8

The front right head lamp of my 2000 Audi A8 does not get voltage. Apparently I am told there are two parts to delivering voltage to the light.
1. The base
2. The balast

One or both are out. How can these be tested?
how much does the procedure cost?

The Item number is I J 0941641 DS HID Balast -- if it is indeed the problem.


Asked by for the 1999 Audi A8
1 answer
swap the ballast left to right to see if the problem moves, but try swapping the bulbs fist. note: don't touch the bulb glass and "DON'T MESS WITH ANYTHING WHILE THE LIGHTS ARE ON!!!" very high voltage.