Re: Tranny Switch Locations

["Jeff Goldberg" <jeffgold@erols.com>]

Zain,

I really gotta thank you for your excellent description of where to find
this elusive back-up lite switch. I followed your instructions and located
it strictly by feel based on your road map. Out of sight for sure. Did this
on my mechanics lift, with the help of a mechanic and it was no picnic, but
doable. Without your instructions, there was no chance of getting this done.
I now have backup lites cus the switch was fine, just had to connect the
wires to the proper switch. My mechanic called his friend at a dealership,
before I begged the list for help & he was told the switches fail to
activate due to a common fault with a spring breaking in the tranny. I
refused to accept this as the final word, and thanks to you I have backup
lights.

I am including your post below to help someone else in the same predicament.
My backup lites disappeared after a clutch job, so I knew they worked.

Jeff
86 4KCSQ Daily Driver (2 decals)
86 4KS      Spare

============================================================================
,
   The back up light switch is located behind the center differential lock
vacuum servo on the passenger side of the transmission.  The servo is
covered by
a tin shield and it makes the switch hard to get at it;  you'll have to feel
around behind the servo to locate it.  I had my 4kq inspected about a month
ago
and ran into the same problem.  To get at it, I removed the passenger side
wheel
and reached inbetween the subframe and body.  You might want to take a
course in
Yoga before you do this :).  You'll need a ratchet, extension and I think a
22mm
socket (I'm not certain - I'm used to VW backup switches which are smaller.
I
just remember this one being larger).  Once out, I tested for continunity
between the two electrodes on the switch and discovered it still worked ---
the
button on the bottom of the switch just wasn't being pushed in far enough.
I
was in a bit of pinch because I was having the car inspected the next day
(and
it was late) so, I stuck it in my lathe and took a little off the base of
it.  I
put it back in and it worked fine.
  This is a popular part to have go bad on a 4kq.  You can test it without
removing the switch by turning your key to the "on"  position and touching
the
two wires going to the switch together.  If fixing/changing the switch
doesn't
work though, I'd inspect the wiring harness that comes into the trunk lid on
the
driver side (you'll see it going into the lower driver side corner of the
trunk
lid).  I've seen a number of 4k/80/90 Audi's where some of the wires in this
harness have actually broken because they've flexed so many times (I ran
into
this with my 4kq too).  If none of the lights on your trunk work, than this
is
definetely the cause.  The last and most obvious cause could simply be a set
of
dirty/cruddy light sockets.
   There is another switch a little further back on the center differential
on
the passenger side.  It's for the center console  light which shows your
center
differential is locked.
   You're right about Bentley --- when I had this problem it drove me nuts
trying to find an illustration of the BU light switch location :).

Good Luck, Zain