I need to fix it by Friday!
I have a 2001 F250 V10, 150,000 miles, gas, very basic truck (no power windows, no cruise, no security system, no power locks, etc). In it's previous life, it was an IDOT highway truck I purchased at auction in 2005. Used primarily to pull horse trailer, less than 2000 miles per year. Stored under cover when not in use. Windshield leaks very little, but generally not used when raining.

Last week, 9pm, horn starts blaring solid tone. I go out and unlock door, open door, it stops. I start truck, still fine, turn truck off. Lock door, close door, starts blaring again. I reopen door, leave unlocked, close door, then get intermittent beeps. I reopen door, disconnect battery because it's late, I was going out of town, and felt bad for my neighbors. Just got back in town, too afraid to reconnect battery and not be home in case it starts going off again. I had last used the truck about 36 hours before the horn started going off, weather about 70 degrees overnight.

I've read other threads, but can't find one that fits (I have no cruise, kept out of rain, not freezing cold, not diesel).

What is my easiest/cheapest fix? Find and pull fuse? New fuse or would the problem still be there? While I am not a rocket scientist or vehicle expert, I can read and follow directions if someone can provide directions.
Thanks so much for helping me out!

 

Makes me wonder if perhaps the previous owner installed an aftermarket alarm system that's now acting up.

 

Could be any one of the following:

Horn relay
Airbag
Clockspring
Gem Module
Wiring.

 

Thanks for the replies! No aftermarket security system...the one and only previous owner was the Lake County IL DOT.

If I remove the fuse, and it clicks like it is trying to engage the horn, will I run the battery down?
Thanks!

 

I mentioned this because ... years ago I had a E250/350 cargo work van. I drove it for several years thinking it had DRLs. When they failed we took it in for repairs.

Turns out it didn't have DRLs, instead it had an aftermarket alarm system with a provision for burning the lights while running. It took Ford several hours to locate the hidden box and disable the add-on.

Also if it clicks then it is drawing power, so eventually it would kill the battery and possible burn out the clicker (relay).

 

Thanks, Army RET!

I did remove 2 fuses, the Relay and the small fuse that the owner's manual said was for the horn (and horn was the only thing identified in the owner's manual for these fuses, not tied to anything else).

I heard no clicking, but it could still be intermittent I suppose. Can I try just removing the small fuse and leaving the Relay in? Would it still click then (if it's going to click at all)?

Both fuses look good (no green, not bent). Would it be worth it to try to replace the Relay hoping that's what's bad?

Would I solve the potential clicking/draining battery problem by simply removing/cutting the wires at the horn and taping them off? If so, where can I find the horn? Owner's manual is very basic and doesn't show this. Thanks!

 

A fuse will not be your problem although pulling one may be a temporary solution. The problem is that the horn relay is energizing when it should not.

No.

It really does sound like water has gotten into the GEM module. How likely is that possibility?

 

Windshield leaks slightly. Truck stored inside and rarely (but yes) driven in rain.

Is it an easy swap-out for a new GEM module?

I do need to use the truck on Sat, so maybe the fuse is a good short-term answer?