Hi Mark,
I have a similar problem with my 96 S6. The vacuum pump is located under the rear passenger next to the battery on the outside, wrapped in foam - it isn't fixed down to anything. Can you here the control unit attempting to activate the pump but there is no sound or action after the control is depressed - either from the remote or the switch on the driver door?
The control unit/pump part number is 4A0 862 257G (or J) for the unit with infra red remotes and 8L0 862 257B if you have a RF control unit. A new unit is approx US$380. Easy do-it-yourself fix, but when dismantling the middle connector must be removed first and replaced last when re-assembling - Bently repair CD says so.
Good luck,
Tony Ottawa
I've just bought a 1997 A6 - the central locking doesn't work. are
> they vacuum operated? where can i find the pump? i've checked for a
> fuse (can't find one) and if the wires are connected to the switch on
> the door (they are). does it have a relay?
>
> don't want to pay audis labour charges if it's something really
> simple...
>
> thanks