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