IHADAV8.com - Turbo Buick Tech, and Nonsense

Tech Area => General Buick Tech => Topic started by: poppy1440 on January 11 2016, 11:14:40 AM

Title: Cruise control
Post by: poppy1440 on January 11 2016, 11:14:40 AM

Hello,
What causes the cruise control module to suck in as soon as vehicle is cranked whether cruise is on or not.
I didn't see this scenario in the trouble shooting on vortex Buick.
Thanks

Title: Re: Cruise control
Post by: poppy1440 on January 11 2016, 11:10:52 PM

I just noticed that I don't have any check valves in any of my vacuum lines.
Could this be my problem.
I have always had this problem I just kept the vacuum line off the servo but the lack of a check valve may be my problem.
What do y'all think

Title: Re: Cruise control
Post by: Steve Wood on January 12 2016, 12:41:53 AM

I don't remember a check valve in that line...am not looking at a car at this moment...

Title: Re: Cruise control
Post by: daveismissing on January 12 2016, 09:03:14 AM

I'm thinking the control module directly (via wires) controls the the vac modulator?
I'm nowhere near my manuals

Title: Re: Cruise control
Post by: poppy1440 on January 12 2016, 10:13:29 AM

If I crank up my car with the vacuum line connected to servo and connect the throttle cable to the throttle body.
It will just suck in and floor the gas pedal.
Needless to say I don't have it hooked up

Title: Re: Cruise control
Post by: poppy1440 on January 12 2016, 10:28:11 AM

Maybe the diaphragm is bad in the Servo

Title: Re: Cruise control
Post by: daveismissing on January 12 2016, 01:24:22 PM

or the control module or the wire in the column. Got any spare parts? column stalk? electronics module?

Title: Re: Cruise control
Post by: Just a Six? on January 12 2016, 02:49:42 PM

I know there is a check valve in the system but I'm not sure exactly where because I'm missing it!
Mine wont engage & I just never spent the time to try & fix it.

Title: Re: Cruise control
Post by: Pyro6 on January 12 2016, 06:30:38 PM

I'm looking at the Alldata vacuum diagram, there is supposed to be a check valve from the vacuum source. I don't think that would be the problem though. If it failed closed it wouldn't get vacuum, if it failed open it would just feed the servo without delay. All the actual vacuum switching is done inside the servo. So, if the servo switching is faulty, it would get vacuum all the time. If he PCM is faulty, it could tell the servo to open the vacuum switches when they shouldn't be opened. I think if you just electrically disconnect the servo and start the engine, it shouldn't engage. If it does, the servo internal vacuum switches are stuck. If it doesn't, the PCM is probably sending the wrong command. I don't think it would be the brake switch, but to check that, just disconnect it and start the car.

Title: Re: Cruise control
Post by: Steve Wood on January 12 2016, 07:13:08 PM

I remembered today, driving down the road, that the check valve is that "fat" Tee connector on the firewall that receives vacuum via the metal line off the plenum vacuum block.  I also don't believe that is the problem.