Cruise control

[Joe Yakubik <75363.2524@CompuServe.COM>]

Wanted:  Cruise Control control unit (or some really good advice)

My cruise control doesn't work and I can't figure out why.  It went out some
time ago (just prior to a long trip, naturally)  but I couldn't be bothered to
fix it then.  I had some time this weekend so I poked around with it.  In true
Audi form it teased me with solutions.

I started with the vacuum system -- lo and behold the hose to the
bellows/actuator was off.  This is gonna be easy, thinks I.  A short test drive,
no cruise.

A vacuum test -- system okay.  Time to start spelunking under the dash and
following the troubleshooting checklist.

I get to the "check the SET button" step and get a bad result.  Bentley says
"Replace switch".  I say  "No way.  I can rebuild it.  Make it better, stronger,
faster...".  I open up the steering wheel cover and figure out a way to remove
the guts of the cruise control switch without removing the steering wheel or
anything else.  I discover a broken wire.  I think  "Not so easy, but pretty
straightforward".  A few computer parts, a little solder, and I feel ready to
cruise.

A short test drive, no cruise.

Back under the dash, more spelunking.  Hmmm, maybe I didn't get the connector
seated all the way down.  A short test drive, no cruise.

Re-accomplish the troubleshooting checklist.  The switch repair appears to be
functioning correctly, the pump works, the pump valve works, the clutch and
brake switches work.  

I got to the "test the speedo signal" step and stopped.  My speedo works, so I
assume the speedo signal is good, too.  Is this a bad assumption?

My logic is:  since all the peripherals appear to be working correctly, the bad
component must be the control unit.  I did the tests without taking the control
unit out.  You can test the components, but I don't think you can test/replace
the control unit without pulling the dash.  If possible I would like to plug in
a good, working control unit to make sure I haven't missed something before I
pull out the dash.  Anybody have a control unit for a 5k/200 lying around they
want to loan me with an option to buy?

Joe Yakubik
'91 200tqw