Date:         Wed, 29 Oct 2003 14:12:44 -0700
Reply-To:     Chad Morris <chad@ALLMORRIS.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Chad Morris <chad@ALLMORRIS.COM>
Subject:      Cruise Control
Content-Type: text/plain; charset="iso-8859-1"

Hoping someone can give me some help understanding how the factory cruise control works.

The cruise control on my automatic '89 Carat was acting up.  When I tried to use it, the speed of the van would gradually decrease, even on flat roads.  Forget trying to use it going up hills.   I looked everything over, readjusted the linkage from the diaphragm to the throttle, with no appearant change.  After giving it more thought, I surmised that the problem must be due to a vacuum leak somewhere in the system.  To  test my theory, I disconnected the hose that runs to the valve on the brake pedal.  In other words, my cruise control setup now had only a single hose running from the diaphragm to the vacuum pump.  I took the van for a test drive, assuming that I risked the cruise control not switching off if I tapped the brakes, which meant I would have to be sure to manually switch off the cruise control.

The results of my test:  Cruise control works great!  It even maintains speed going up-hill when the auto tranny downshifts.  So I have concluded that the vacuum loss is definitely somewhere in the hose that goes from the vacuum pump to the valve on the brake pedal.

What I am still puzzled about:  What surprised me was that when I tapped the brakes, the cruise control switched off, even with the hose going to the valve on the brake pedal disconnected.  My question, therefore, is why do I need to have the valve on the brake pedal connected?  Is it some kind of backup safety system in case the cruise control malfunctions?  I would appreciate your input as I see no point in reconnecting the hose going to the brake pedal valve when everything works great as is.  "If it aint broke, don't fix it."

Chad Morris
'89 Carat
looking for a 7 passenger Westy Weekender