Geico266

It started yesterday. If I set the cruise it will immediately start slipping and not hold the speed. If, after I hit set, and it starts to slip I can push resume/ accell and it will speed up and hold the speed within 1-2MPH. If I hit canel and resume it will resume speed no problem. Just when I hit set the first time it won't hold the speed. Any ideas from the techs?

torquefan

That's a weird one. It acts like a vacuum supply problem, but why does it only do it the first time? Also, with low vacuum, they won't usually speed up with the "accel" button. It would really be nice to hook up a scanner, because Dodge has a decent data stream for the cruise system. Try pulling up on the brake pedal with your foot while pushing "set" the first time. Maybe your brake switch is a little out of adjustment. Otherwise, I don't really know what to tell you.

Geico266

Well, now it won't hold even if I hit accell. It slowly lets go, not all at once, like it was a vacuum leak, but I checked the control unit with a vacuum tester and the control unit hold a vacuum fine. I also checked the vacuum system with the engine running and that is fine also at 26".

I tried the brake peddle thing, no luck.

Should I try replacing the cruise control solinoid?

or the vehicle speed unit on the trans next?

torquefan

On your truck, the cruise control gets its speed signal from the sensor on the rear differential, as does the speedometer. Theoretically, if the speedo works fine, the sensor won't be an issue with the cruise. Did you check the vacuum right at the servo? I don't think it's an electrical problem because of the gradual slowdown involved. 90% of the cruise problems I see with these trucks are vacuum related. If vacuum supply is good right to the servo, it may be time to try a new servo. Possibly one of the internal valves not sealing completely. They are relatively simple inside, I remember having one apart before, but I can't remember if I had to destroy it to take it apart. The servo is not as expensive as one might think, but kind of a pain to change.

Geico266

I think you are right on track, and I thank you for the info.

I pulled out the old servo and will replace it in the morning. I'm pretty sure its the servo due to other posts after I "searched" it on this site. System vacuum was good at 26" hg, and everything held a vacuum with the engine off, hense no leaks. I'll let you know if it works after I replace the servo.

Battery acid had eaten some plastic parts under the battery tray, but not the vaccum lines. I sure am glad I got Optima Red tops now! No more battery acid leaks!

Geico266

It was the cruise control servo valve.

Thank all!


I'm a cruisin machine now!

torquefan