Horn Stuck after new battery install!
 

Battery died on Saturday. Installed new battery last night. I first connected the postive. The second the negative made contact, my horn went off.
This is a constant horn. Not the on/off-on/off alarm sound. My car would also not start up. Finally after clicking an alarm switch under my dash, I was able to get my car to start, but the horn would not turn off.
I finally just removed fuse 26 and now the Expo works, but I have no horn.
I purchased the vehicle last year from an auction, and everything has been good, until now. I believe it may be a function of the alarm installed at dealership. Should I just have the alarm removed? I have googled for hours and searched this forum without any success. Has anybody heard of such an alarm function?
Any help would be greatly appreciated.

George :-huh

Sounds like the relay for your horn is stuck. What year is your vehicle ?

Did you try locking then unlocking the vehicle with the remote? That might reset the arming of the alarm.

2004 EB EXPEDITION
 

It is a 2004 EB Ford Expedition. I tried pushing everything on my key fob, locking and unlocking manually. Even after driving for a while I tried putting the fuse back in and still the horn goes off.

George

I did a bit of searching and found this thread. I know it's for a Mustang, but since it's Ford the solution could be the same.
Replaced old battery and now cannot start vehicle. Alarm system issue? - Ford Mustang Forums

That definately sounds like my issue....Thank You. Now do you think just removing the alarm will correct the issue. In the post you linked to, the individual had the alarm fixed. At this point I just want to have a working horn and doors that unlock/unlock from my keychain.

Sure, no alarm, no issue. You will have to find and bypass the starter kill relay so that the vehicle can be used for more than just a lawn ornament. ;)

are we talking aftermarket alarm/remote start system ..........doubt a FOrd system would do that after a dead battery

I believe it is a dealer installed addon to the Ford Stock alarm?

On a side note, I had the hardest time finding the Ford Manual last night and I saw many threads with out a resolution looking for the manuals. So in case anyone is looking and hops upon this thread, you can find them right here:
https://www.fleet.ford.com/maintenan...ls/default.asp

Page 259 of your owners manual shows the horn relay to be R305, however it also says, "Note: Relays R301–R305 are not serviceable components; see your dealer or a qualified technician for assistance".

That just means do not take the relay apart and try to repair it. The relay itself just pulls out and a new one plugs right back in. However, his issue isn't with a relay, it's with the alarm signal wire that runs to the horn relay coil circuit. He has to locate and remove it.

It appears you horn relay can find ground from either the horn switch or the alarm system. If you isolate the source of the ground you have found the problem and can fix it. Sounds like it is alarm related. Does the alarm have a fuse? Did you pull it? Does the horn still sound. Pull the horn switch fuse. Does the horn still sound? Have you swapped the horn relay with a known good one? You can procede like this.

Thanks for this post, and for the mustang one. That's exactly what is happening to my F250 2006. But, I gotta add that's happening when temps drop under 45 degrees; yeap! sounds weird but real. I can spend in summer every night sleeping all night long, but when falls shows I have to disconnect batteries (both) to avoid jumping out of bed to not bother my neighbors with my horn screaming aloud.

We have the same problem. Have you found a fix, if so can you please post it.

Nothing yet
 

We are gonna take it to the dealer this week with some printed paper of this forum. But, we already know we have to spend some buck regarding on this matter. We just want to get rid out if this. Let see what the dealer has to say about it. I will post further info...
What's your ride? I would like also to talk about it to the dealer and see.
:-duel1