I have a 91 Dodge Ramcharger that has an Automate 600 (DEI) alarm. If I unplug the alarm module; the cruise control works fine. Plug the alarm back in and no cruise. I have looked over most of the slices and can't find anything out of the norm. Really puzzle'n. THX
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Work hard...Play harder...Laugh as much as you can.
Possibly the factory cruise monitors the engine's tach rate? (Most don't, I believe.) See if disconnecting just the tachometer input to the unit makes it work again.
Come to think of it, the DEI stuff has quite a few separate plugs on it. If you undo just one of those plugs, then test your car......then reinsert it, unplug another one, and drive again...........you should eventually be able to at least narrow down where the problem is coming from.
I had that same problem with my wifes Dodge Neon, I traced the problem down to the ground wire of my remote starter which really isn't very specific, but i ended up installinmg a switch under the dash on the ground wire so I could basically unplug the unit by removing it from ground. This allowed me to use my cruise when i needed to. Then a year later I had some trouble with two starter kill relays that I ended up having to cut out and reconnect the starter wire to get th ecar to even work properly, so i got th eidea to cut out the starter kill form my wifes Neon, and it solved it. That was also the reason I was getting a check engine light all the time.
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J Rilla
Owner/Installer