I’ll be updating this post when I get the time, but I recently bought some SWEET Sonar headlights off of ebay for my Audi S4.  The problem was they came with the WRONG WIRE HARNESS. So I had to bust out the Multimeter and figure out which wire did what in the stock Audi headlight harness.

I’ve created this basic wire diagram of the harness, it’s not too complicated. In fact, there are actually some bonus wires you can tap into.  As far as the color-code of the individual wires, I wouldn’t pay too much attention to them.  Both my left AND right headlight harnesses had totally different color schemes.  Just follow the numbering of the wires themselves.

The install wasn’t really difficult, just took about 2 hours.  The Sonar headlights fit perfectly and, although they are not HID Xenon bulbs, they are pretty stinkin bright. I no longer get the cool blue of the stock Xenons, but I do get a sweet purple/yellowish glow.  I’m also proud of the additional daytime running light which wired right into the daytime wire that was NOT used in the stock harness!  The halos are cool too, but alas are a little cheesy since I don’t drive a BMW.  But when it’s dark and all the lights are on it looks good.  And the black housing looks way hotter than the stock reflective housing.

Hopefully this post helps someone out who bought the Sonar A4/S4 B5 Audi headlights and has no clue how to install them.  Just take the plunge and snip the wires. That will get you motivated.