re:CRUISE CONTROL

[Steve Valin <steve@sgi.com>]

afinney@tamsconsultants.com asks:

<< What I'm wondering is why the plunger switches
on the clutch and brake interupt the flow of power to terminal
3 of the control unit. The switches don't even see power until
the brake pedal is depressed and power is sent to the brake
lights. So what is the point of then interupting this flow if it
was only just initiated? >>

I was wondering the exact same thing on my '88 90Q.  It sounds like
the cruise control circuit is pretty much the same for all Audi's
of this period.  I posted this same question to the list last week
and got a very good answer from Joe Yakubik, who's been struggling
with his CC on his 200.  

Basically, the gist is that the switches find a ground path thru
the brake lamp module (of thru the lamps themselves, if you don't 
have a module).  The CC module is looking for a connection to
ground, not +12V.  Pretty perverse, eh?  I'm not sure why Audi did
it this way, instead of going directly to ground or +12V, like one
would expect.

-steve

--
Steve Valin	http://reality.sgi.com/steve_engr	steve@sgi.com
    		"Time wounds all heels"  -Crackerbash