[s-cars] Miracles Never Cease - Door Lock Problem Solved!

[Mike Bishoff]

This is an update from an age-old problem I've been having with my 92 S4.
For the last year or so, the car has been locking itself when entering or
exiting the vehicle. The problem was intermittent and often caused the
ignition to disconnect requiring me to open the window and while using the
key, unlock the car from the outside. This temporarily allowed me to start
the car. Of course, the alarm set and often announced that I was breaking
into my own car. The intermittent-ness of it all was causing the most
aggravation!
 
So, problem solved. I was fiddling around with the battery a few days ago
and touched the large module outboard to the battery that's wrapped in
rubbery material for shock absorption. No doubt this is the door lock vacuum
motor/ignition disconnect/alarm set module probably called something fancier
than that. When I touched the top of the box, the door lock vacuum motor
would activate and lock the doors. Pretty odd stuff, so I tried it again and
again and got the same results. I doubted that Audi would plan to run the
vacuum motor when the outside of the box was touched.
 
Pretty suspicious, which then led me to pull the box out and see what's
going on. The top of the module comes off pretty easily and exposes the
bottom side of a circuit board. Past that, the next thing I noticed was
something rattling around inside the box. After a few shakes, a small pop
rivet fell out. More suspicion.
 
The board doesn't come out that easily as it turns out because it has a
vacuum switch attached to it that's attached to a vacuum hose connected to
the vacuum motor. After some tugging, the vacuum hose disconnected and I was
able to pull the circuitry out. Putting this back together was as medium
effort in patience. How they assembled this in the first place is a mystery.
 
I couldn't find a place where the pop rivet may have come from - perhaps in
a very hidden place, but I looked hard. Since this is a closed unit, I'm
fairly certain it came from inside, but not 100% sure. I looked for loose
wiring, cracked solder connections, etc and didn't find anything, so I
temporarily hooked up the unit and lo and behold the locks, alarm, ignition
AND the infrared keys now all work.
 
I can only assume now that the pop rivet was rattling around on the
circuitry and wreaking electronic havoc. Fortunately this was a no-cost
repair!
 
Thanks to all that may have made suggestions in the past to help me resolve
this problem. Phew!
 
Mike - Seattle, WA