90Q cruise control problem

[steve@ipecac.engr.sgi.com (Steve Valin)]

So I have an '88 90Q and a Bentley for it.  I've been 
tracing down the cruise control system trying to find 
the reason why it's not working.  I noticed that the
way the brake and clutch switches are wired makes no 
sense.  I can't figure out how this damn thing works!

The cruise control system has it's own clutch and brake 
pedal switches.  These are wired in series and connect
to the CC module on one side and the CC pwr switch  on the
other.  I would then think that the switch should then 
be connected to +12V so that the CCmodule would be able to
detect if either the clutch or brake is pressed.  But no,
it's wired instead to the other brake switch, which is 
normally open until the brake is pressed.  This means
that when the brake is not pressed, no current will flow
thru the CC switches.  When it is pressed, 12V is passed
on, only to be blocked by the CC brake switch.  It's like
connecting the inputs of an XOR gate to a signal and it's 
inverse - you'll never see a 1 at the output!  

I must be looking at this system incorrectly.  Does anyone
know what's going on here?  I have gone thru this with the 
voltmeter, and it does seem to behave like I've stated.  If
something were wrong with this pedal switch circuit, it would
keep the CC from working.

Dazed and Confused,
-steve

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