My horn hasn't worked in over 8 months and now all of a sudden when I'm driving it just keeps honking and won't stop on my 1999 dodge caravan

It is a known issue. Lots of ideas, mine is a to call out an auto-electrician with a pro-grade scan tool computer. When the battery is disconnected, and the key is in the ignition and the doors are closed, the horn shouldn't go off. Make sure you leave the windows open in case it self locks. After that, you need to do a security reset. There are 3 ways here.

https://www.google.com/search?q=1999+dodge+ram+1500+security+reset

https://www.google.com/search?q=1999+Dodge+Ram+1500.+How+to+make+the+horn+stop+going+off+constantly

Is it possible that the panic button is stuck on the Remote?
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open the hood and look in the under hood electrical fuse relay center should be a relay that is marked horn or you can pull the fuse marked horn.must likely its the air bag on steering wheel.it coukd be the alarm but you would have to take to shop or get a book to help you, good luck

Security engaged, Lock and unlock doors with key until horn stops.

no help has to be checked out by elec person

the reason it is doing that is either the pad on the steering wheel is shorting as if you are pressing on it, or the clockspring under the steering wheel is shorting to ground. there is a horn relay in your fusebox inside the cabin; you could disable it there by pulling out the relay. don't pull the fuse because it carries other circuits as well. I couldn't find the exact relay position, but just feel them with your finger while someone honks the horn; the one that's clicking with the horn activation is the one to pull out. I can get you the layout of the fusebox but you really don't need it for that.

this sounds like you might have a short or the live wire is touching another part of the inside of the cover where the horn wires are, just pull off the middle and check the wires are ok and not touching each other..hope this helps

Clock spring is probably bad. There may have been a recall on it.

I would start with the horn relay. There's a fuse panel near the inner fender under the hood. They should be labelled either on the inside of the cover and/or in the owners manual.

Check under dash, remove black cover on drivers side to access for blown fuse, as well as under hood in fuse/relay box on drivers side. Map for under hood relay/fuse box is on underside of cover.

Look in your manuel, there are steps to change the Key less remote setting to customize it the way you'ld like the car Key less system to work.
Good luck and hope this helps, if your still having problem. Just drive the Dodge dealer and ask the Service adviser to help you out, he or she would be more then happy to reprogram the key less system for you.