I thought it was a vacuum leak but it was the cruise control!
 

Any suggestions what might be causing my cruise control not to engage?

With the engine running and in park what I thought to be a vacuum leak turned out to be the cruise control sucking the rod that goes to the carburetor back thus causing a very high idle. I removed the rod that is connected to the cruise control servo at the carb and my idle dropped back to normal speed. So I ordered a rebuilt cruise control servo and replaced the old one with the rebuilt one. Engine idle speed now stays at normal idle speed. However, my cruise does not work. Any suggestions on what might be causing the cruise control not to engage? Thanks for your help!

Re: I thought it was a vacuum leak but it was the cruise control!
 

Do you have a wiring diagram for the cruze for your truck?

Re: I thought it was a vacuum leak but it was the cruise control!
 

I do not have a wiring diagram. I'll do a search and see if I can find one for the cruise control Thanks, for the reply.

Re: I thought it was a vacuum leak but it was the cruise control!
 

Some Cruise Control units utilized a vacuum release at the brake pedal. check to see if the may be hung open, causing a leak.

You can also try disconnecting the wiring harness to se if it returns to normal. That would point you towards an electrical issue. if not disconnect the vacuum and look for normal. This way you can isolate the issue to electrical or vacuum.

Re: I thought it was a vacuum leak but it was the cruise control!
 

Thanks Wgesnerjr, I'll look and see about the brake switch. I do have a hose coming from the cruise control going down into the firewall, I'll check it out!

Re: I thought it was a vacuum leak but it was the cruise control!
 

The CruiseMaster and Cruise III training manuals are posted in the manuals thread.
The 1979 service manual has a pretty decent section on CruiseMaster too.
There is a vacuum switch on the brake pedal on at least one of those systems.