I have a 1997 1500 and the other day I went to use the Cruise control and it turned on but it didn't engage. Does any one have any idea what is wrong?

 

Have you checked the cable to the throttle body? Haven't had an issue with my dodge but I've had the cable come undone on my mustang, cheap ford parts

 

Make sure the vacuum line hasn't dry rotted, and broken as well.

 

Like HeyYou said, check the line..Battery acid can corrode the lines and cause the a/c and cruise to malfunction.

If you turn on your a/c and accelerate hard/drive up a hill, and the a/c switches to defrost (blows out defrost vents instead of out the normal ones) then check this out as well as the TSB: http://autorepair.about.com/library/faqs/bl073h.htm

 

I need to check my vacuum lines user that tray cuz I have th af issues but not my cruise control works

 

I know that none of my lines are corroded because I had my whole and I mean the whole truck torn apart.But I will look tomorrow afternoon.

 

The plastic line gets brittle. Follow it around to the passenger side of intake and check ther also.

 

Also the cruise control servo, or whatever its called, little canister under the battery tray, can get battery acid dripped on it and leak, not hold vacuum. I had to replace mine with one from a junk yard to get my cruise working.

 

I checked all the hoses under the hood and they are all in tact.

 

The line you are looking for is under the battery tray, not just the lines under the hood.