How does cruise work?

[urq]

The vacuum module has a pump and a vent valve.  If the computer wants to
increase the throttle it runs the vacuum motor and if it wants to reduce the
throttle it opens the vent valve.  When the cruise control is off the vent
valve is opened.  

You can test for leaks by removing the line at the pump ... the rest of the
system should hold vacuum.  If you don't have a vacuum pump you can push in
the vacuum motor that attaches to the throttle and then seal off the open
end of the hose you pulled off the pump.  Now release the vacuum motor ...
it should remain in place.  If the motor returns to the rest position there
is a leak.  A leak may be due to a pedal switch that is not adjusted
correctly or a split line at a fitting.  

Steve Buchholz

-----Original Message-----

Specifically the vacuum portion. 
 I guess the the electronic portion uses a set number or voltage then
compares to signal from speed sensor.
My question is about the vac portion. Does the vac motor run all the time
and use a bleed of sytem to position the throttle?
Or does the vac motor run when it needs to pull open the throttle? Seems it
would still need a bleed off to change or quickly close the throttle?
Anybody know for sure?
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