Thanks Larry,  I think you are right that there is some sort of ground or other wiring problem, but I couldn't find it.  I followed the Bentley troubleshooting routine which tests ground in the first step (using a test light) and the light came on.  All the troubleshooting tests passed initially except the pump.  After I got a 2nd used pump and it didn't run, I checked the pumps directly at the battery and they both ran.  And with the jumper still in place to run the pump manually, I get 12.x volts at the plug (green +, brown -), and I checked resistance on those wires from the front plug to the back where they plug into the motor.  I think it was fine, .08 ohms.  Maybe both motors are actually bad and it just takes a direct battery connection for them to get enough juice to run.  Or maybe there is a wiring issue elsewhere.  I am stumped after 3 days.

I can see how troublehooting electrical issues is difficult on a list.  THere are so many mistakes I can make and then give misinformation about what I think I am seeing.  I have learned a ton about the cruise control system over the weekend, but still cann't find the problem.  I have the van at the shop this morning.

Thanks 
Dave

--- On Tue, 12/28/10, Larry Alofs <lalofs@gmail.com> wrote:

> From: Larry Alofs <lalofs@gmail.com>
> Subject: Re: 87 Cruise Control--followup
> To: "David Vickery" <david_vickery@yahoo.com>
> Cc: vanagon@gerry.vanagon.com
> Date: Tuesday, December 28, 2010, 5:50 AM
> Sounds like a ground problem.�
> If the ground wire for the pump also
> shows 12v, then it isn't connected to a solid ground.�
> Do you have a
> wiring diagram?
> 
> Larry A.
> 
> 
> On Sat, Dec 25, 2010 at 5:37 PM, 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. �I even cut the plug and
> connected directly to the wires to be sure I was getting a
> good connection. �I don't know how it can show 12.x volts
> at the plug but not have enough power to run the pump. �I
> am not that good at using my multimeter but maybe there is a
> way to diagnose further. Maybe something is loose enough
> that it shows it has power, but it isn't able to give any
> current? �I did set the multimeter to 10A and tried to see
> what the pump was drawing, but with the pump not running, I
> don't know if the value I got has any meaning
> > �.05amps. �If no one has any suggestions, I will be
> headed to the shop.
> > Thanks
> > Dave
> >
> > -- On Fri, 12/24/10, David Vickery <david_vickery@YAHOO.COM>
> wrote:
> >
> >> From: David Vickery <david_vickery@YAHOO.COM>
> >> Subject: 87 Cruise Control troubleshooting
> >> To: vanagon@GERRY.VANAGON.COM
> >> Date: Friday, December 24, 2010, 5:07 PM
> >> 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
> >>
> >
> >
> >
> >
>