Tech article: Window Switch rebuild

[Scott Fisher <sefisher@cisco.com>]

Haven't I read here that the power-window switches tend to go out on
mid-Eighties Audis?  If so, this article will help many others, since
I'm sure that 4000 and probably 5000 series cars use the same
power-window switch gear that my '83 CGT does.  It's literally a
five-minute fix.

Over Thanksgiving weekend, the Bay Area had its first serious
rainstorm.  Naturally, not only was that the weekend we had to move, it
was also the weekend that the passenger's-side window switch in my '83
CGT decided to fail, with the window in the partway-down position.  It
would roll further down but not up.

I kludged up a solution in the garage of our new place: pulled both
switches, swapped the (working) driver's side to the right and rolled
the window up.  Neat, kept the interior dry, and didn't cost anything or
require serious tools (which were still in transit).  But I knew I'd
want to get the passenger's window going sooner or later.

So on Sunday I fixed it twice.  Here's the story:

When I picked up this car from my friend Daren, he gave me a box of
spares which included a couple of different styles of power window
switch.  One setup included the whole panel and two switches, though
apparently from a different style of car.  My Coupe has the nifty
lighted switches; the spares didn't, and also had a much larger bezel
around the rocker switch.

Naturally, only one of the spares worked, so I couldn't install them
both and have matching switches.  I sighed and installed the working
spare over the passenger's window, figuring that with all the cracks in
my dash it wouldn't REALLY matter if the right-hand window switch didn't
match the left-hand one.  I screwed the little panel into place, popped
the switches into the trim panel, and climbed out of the car.  Nope, I
wasn't satisfied.  

So I figured, what have I got to lose?  The original switch doesn't
work, I can't make it worse than it is now... Disassembling the switch
turned out to be easy; the bezel just snaps into (or out of) place, and
was easily removed with my handy machinist's scribe to lever it off. 
Similarly, the rocker switch pops out; the rotating pivots are how it
clips into the switch base, so if you lever the side walls of the switch
base away from the rocker while lifting the rocker out, it just slides
apart.

Be sure to be holding the switch with the rocker side facing up, because
here's how the switch works:

The rocker has two plastic cylinders which project down into the switch
base.  They in turn press on a pair of ball bearings, which rest in the
middle of a pair of shallow metal Vs.  These Vs make the electrical
contact; it'll be obvious when looking at them how they work.  I shook
out the ball bearings (carefully, I've seen tiny ball bearings go
skittering under things) and lifted out the metal Vs.  They turned out
to be symmetrical and identical; that is, they could be installed 180
degrees or swapped from side to side with no problems (to simplify
initial manufacture, no doubt).

On the underside of the Vs there are a pair of contacts, looking very
much like contact-breaker points (for those who remember what THOSE
are).  There's a matching set of points-material contacts in the base of
the switch.

In my non-working switch, it was easy to determine the orientation of
the Vs even when they were out -- the burned contacts gave it away.  A
thin layer of carbon covered the points, and explained why the switch
had stopped working.

I used the straight end of my machinist's scribe, very gently, to remove
the black deposits from the end of the contacts, burnishing them
slightly.  Just to be safe, I rotated the switch Vs so that each
position had one never-been-burned contact and one just-been-burnished
one.  The ball bearings slipped neatly into the valley of the Vs, the
rocker clicked into place, and the proper-sized bezel clicked in just as
authoritatively.

I "gently prised" the non-illuminated switch from the panel, lifted out
the ashtray to get access to the connectors, and tested my rebuilt
switch.  It worked perfectly.  I returned the working spare switch to
the spares box and installed the original, lighted switch.

Now, of course, the passenger's window goes up and down with alacrity,
while the driver's side is a little slow and creaky.  Since I'm taking
some time off work this week, I'll probably pull that switch and spend
five minutes to make it work properly too.

Tricks:

0 - remove the ashtray before beginning, you should then see the white
nylon connectors for the power-window switches.

1 - carefully pry the switch straight out of the trim panel by levering
behind the switch bezel.  It's just held in with a spring, but be
careful not to scratch the trim panel or the bezel.

2 - use the corner of a straight screwdriver to pry the narrow edges of
the switch connectors, which is where the barbs are located that keep
them connected.  The connectors then pull straight off.  Thread them out
from under the trim piece and lift the switches out of the car.

3 - look closely behind the switch bezel to see where it clips to the
switch base.  Again, lever gently with a pointed metal object (if you
haven't yet purchased a double-headed machinist's scribe -- looks like
Dr. Mengele's dental pick -- get one, it's one of the most useful tools
you can own).

4 - if I were doing this again, I'd lever the rocker insert out over a
small cardboard box, just in case the ball bearings drop out.  

5 - if I were a hardware geek instead of a content geek, I'd have
contact cleaner lying around the house, and I'd use that on the burned
contacts.  

6 - be careful not to gouge or damage the contacts when you're cleaning
them up; you don't want to remove metal, you just want to remove the
insulating carbon layer.