I wanted to send an update on my cruise control problem for the archives.  

Thanks to the couple people that responded to my post.  I mentioned it must be difficult to troubleshoot electrical problems on a list because there are so many mistakes a person can make in the testing itself.  In my case, I was using a test light but I also used it as the jumper wire when trying to see if the vacuum motor would run.  Apparently you can't do that, why I don't know.  The test light would light up but the pump would not run.  When I used a jumper wire instead of the light, the motor ran.  

The real problem turned out to be an intermitent brake cutoff switch.  It was passing that tests sometimes and sometimes not.  I tested it for continuity and it seemed o.k. so I ignored it.  After getting the van back from the shop working, I ran the diagnostics again to see what I was doing wrong.

I posted some of what I learned at thesamba which may help the next person.
http://www.thesamba.com/vw/forum/viewtopic.php?t=317214&highlight=

Thanks,
Dave in Fort Collins

--- On Sat, 12/25/10, David Vickery <david_vickery@yahoo.com> wrote:

> Well the pump works fine, so it must
> be something else.� I connected the pump to the battery
> directly and it runs.� BTW, the other wire is for a
> valve; it clicks when you give it power like it is supposed
> to.� And the pump runs when you connect brown and green
> to battery.� The puzzling thing is that I get 12.x
> volts at the plug on the same connectors that I connected
> straight to the battery, but at the plug it won't run.�
> 
> -- On Fri, 12/24/10, David Vickery <david_vickery@YAHOO.COM>
> wrote:
> > Hi all,
> > 
> > Hoping someone can help with my 1987 stock cruise
> control
> > problem.
> > 
> > Background:� My cruise was working well now it won't
> > come on.� I went through the Bentley troubleshooting
> > diagram with a test light and passed the first
> several
> > checks, including the tests for the clutch and brake
> > switches.� Since I passed those tests, obviously the
> > fuse is fine and the on/off button works.� When I
> got
> > to the test for the vacuum pump motor, jumping #4 pin
> with
> > ground it says I should hear the pump come on.� I
> don't
> > hear anything.� With the ignition on and the cruise
> > control in the on position, the test light lights up
> but no
> > sounds from the pump in back.
> > 
> > I tried another pump today (used and unknown
> condition) and
> > I don't hear anything with it either.� So I am
> > wondering if it could be a wiring issue or possibly
> the 2nd
> > pump is bad.� With the #4 jumper in place and a volt
> > meter at the pump in back, I read 12 volts at the plug
> using
> > + to green wire and negative on the brown wire.� I
> > don't know what the green and white wire is for but I
> don't
> > get 12 volts when I try substituting that for the
> green wire
> > with my voltmeter.� When I had the pumps out, I
> tried
> > putting 12 volts to them directly and I don't hear
> anything,
> > but I am not sure if I should be using the green/white
> or
> > green or both with brown going to negative.
> > 
> > If anyone knows how I can test the pump directly and
> what
> > it should sound like if it is working, I would be
> very
> > appreciative.
> > 
> > Thanks, Dave
> > 
> 
> 
> 
>