I have searched for a previous post regarding this problem without success, so I am asking if anyone might know why this is happening....
I just yesterday purchased a beautiful 1990 Seville with the 4.5 engine. Everything is great except that when I turn on the cruise control on the turn signal stem, the dashboard message says "cruise control engaged" but when I try to set a speed, nothing happens. It won't engage to hold any speed. All the fuses seem fine. Could this be a vacuum problem/leak? Any suggestions will be greatly appreciated. Thanks much.

 

There is a vacuum-operated diaphragm that should have a cablecoming out ofit going to the throttle. Find the vacuum hose going to that unit and make sure it's pulling plenty of vacuum when idling. If not, there's a leak somewhere in the hose or it's disconnected. If you have plenty of vacuum, the diaphragm itself may have failed and needs replaced.

 

If it says cruise engaged, that means you've set it, not turned it on. There is a set button and an off/on switch. So assuming the sytem switch is on and you depress the engage switch and nothing happens, I would look at the attachment of the cruise servo cable to the throttle body. Too much slack, disconnected, or hose off the servo would keep it from setting.

 

To both who were kind enough to reply, thank you very much. Your suggestions make a lot of sense and I will be checking into them at my earliest opportunity. I lack a garage, much less a heated space, so I'm hoping to get to this when the weather will be less uncomfortable than the sub-zero wind chills we currently have here in SE Wisconsin. I'll post when I have results either way. (As far as the off-on switch vs. the "set" button, that part I knew about, but even with the cruise system "on", the "set" button has no effect.) Thanks so much again for your willingness to help and sharing your expertise.

 

I've got the same problem with my 2001 Eldorado......any solutions? I do not have a garage either.

Is it worth brining to a Caddilac dealer to check out?