The white box or "transmitter" is located under the rear seat. If it has a brown plug with 9 wires in it, you have keyless. If you just have the plug (it will be under the seat), all you need to do is buy the transmitter or white box part number 8D0 907 335A (external antenna) or 8G0 907 335 (internal antenna). The first one is better but they superceed each other. Once you add the box and plug it in, program your remotes and your done. It's that easy. It will cost you about $475 for the transmitter and $150 for the remotes. All the cars are wired as it is easier for Audi to make the cars as similar as possible and add things easily on the assembly line. The transmitter is a "switch" that cuts the circuit to the lock unit. The key pad simply tells it what and when to do it. I verified this with a multi tester and bought the unit for my car and it worked fine, it's OEM and as usual, the range sucks. e-mail me concerns. Good luck.

Jeff

Why do you need to get it re-programmed? Is the battery dead? When did it stop working? If you do need to re-program it, go to the A4 forum and search keyless. Find the forum on re-programming remotes for a 96, it's different than the newer ones. It's a simple procedure.

you may also have to change the vacuum pump, depending on the model.

Appears that there were quite a few variations
in the early years on the A4.

Looks like you lucked out, and got one of the
later model 1996 a4s.
Mine is an early model. (i believe actually mfg in 1995, but I have to check)

PS don't confuse the boxes under the rear seat.
There is also:
ABS box under rear seat.
Ultrasonic breakin detector control module under
rear seat--this does NOT equal remote ready.