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Discussion Starter · #1 ·
I’ve had my alarm go off on my 2018 F-150 two nites in a row. Got an alert from my Ford app. Went to my shop and behold! Lights are flashing but no horn. Hit the button to stop it and it stops. So weird. Anyone else have this issue?
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It has happened to me twice last year and once last week -- haven't figured out why...
 
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Yes, you are not alone, I have had false alerts, but with the horn and signals. Now what? It either never happens again or becomes a constant annoyance. I looked over at f150forum.com and it seems there are several others with this issue. They seem to point to the BCM and water as the problem and suggest pulling all codes with forscan. Here is the thread (well, one of the threads) Hazards and horn operating erratically . Now his is older (a 2016) but the basics haven't changed. His summary is
UPDATE: It was the BCM that was damaged due to water intrusion due to an incorrectly installed windshield. I ended up taking it to the dealer to have them deal with it, because this late in the game, as a single daddy with an 80-mile round-trip to work every day, I needed my truck to be solid and reliable.

Where I originally was looking at the door harness seals for water leaks, it turned out those connections were good. I'd have never expected my windshield to have been the cause. You get those installed and figure the guy knows what he's doing.

The work order came out to just over $1000. A guy was to come and reseal the windshield, and all was supposed to be well. Then I got a call saying the windshield was going to break upon removal (most likely), and I'd need a new one installed. Work order just jumped up to $1300. After some "discussions" the dealer was able to knock a few hundred off the labor, bringing me back around $1000 to fix everything, All in all, I missed two days of work due to the truck being down, which probably brings the loss right back up to $1500, but such is life. I'm just hoping we are good to go from here. I'm usually really good with preventative maintenance and making sure problems don't get super expensive, but I didn't even see this one coming!
Another issue that causes these symptoms is a low battery.

Mine went off at 2 AM and in a locked garage. I ran the security camera and at the same time it went off a fire truck went by. Who knows? Also I think some or all trucks have a trailers security system built in that Ford kind of screwed up- it is supposed to let you know when someone unplugs your trailer without your key fob nearby. It can be disabled if you see it is on your truck.
 
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Could be the motion sensors.. A moth or fly or whatever flapping around inside the truck can trigger the motion sensors and set it off. I've also had it go off when i left my sunroof cracked and water dripped in.
 

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2018 F150 Lariat 502a with 3.0 Diesel
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Any time a horse fly gets in mine overnight, it goes off. Very annoying.

As for the trailer mention, not sure if that’s on our trucks or not but makes sense. When my trailer plug was messing up (due to a wad of dirt being shoved in there 🤦🏻‍♂️), I got random trailer messages while nothing was connected. If you’ve ever seen those, it could indicate a trailer wiring issue back by the plug that, if that is monitored and triggers the alarm, could give problems.
 

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Discussion Starter · #7 ·
Thanks for the responses. My next question that I should have thrown in is I didn’t let mine go for very long before turning it off. Has anyone waited to see if the alarm would finally quit and reset? That’s my next test. I went ahead and removed the battery cable for 10 mins to see if this wouldn’t reset whatever is causing it. I’m afraid if I’m out of town and it goes off is it going to run my battery down.
 

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Discussion Starter · #9 ·
Alarm went off for a 3rd night in a row. This time I waited for 5 minutes and it never cycled to a reset. I was able to disarm it with my Ford app so this gives me hope if I’m out of town and it appears.
 

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Certainly an aggrevation. Did you try using electric tape squares over the inside sensors in the overhead console? Mine goes off about 1 time each week but it is because I lock it and forget my dogs are inside while shopping and about the time I get into a store off it goes. As you mentioned I just silence it with the app and leave the truck unlocked until I get back out. You would think I would learn...
 
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Discussion Starter · #11 ·
Certainly an aggrevation. Did you try using electric tape squares over the inside sensors in the overhead console? Mine goes off about 1 time each week but it is because I lock it and forget my dogs are inside while shopping and about the time I get into a store off it goes. As you mentioned I just silence it with the app and leave the truck unlocked until I get back out. You would think I would learn...
I guess the third time was a charm because it finally stopped. I think several folks mentioned bugs in the cab and I was out mowing, etc. Something probably got in. Thought I was going to have to burn some sage…
 
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