Horn went crazy, sounding for 30 seconds while driving. Help?

[OutofNowhere]

I left my house this morning like always, got about halfway out of the neighborhood and was fiddling with the volume controls on the steering wheel. The horn suddenly went off, and sounded constantly for 30 or more seconds. It wasn't like the horn sounds when the alarm is triggered, like "beep, beep, beep" with silence in between, but one long "beeeeeeeeeep" that just kept going. IDK how long really, but felt like an eternity!

Trying to stop it, I hit the horn in the center of the steering wheel, then when that didn't work, I stopped and thought to shut the car off so I hit that button. The horn stopped, but the car didn't turn off, and I don't really know if anything I did stopped the horn, or if it just hit that 30 second mark and stopped on its own.

I have no idea what triggered this. I don't have the interior sensors armed ever, and they wouldn't be armed while driving anyway. Is there some panic alarm that I managed to accidentally trigger while using the volume controls on the steering wheel? I may have pressed the track forward button and volume up button simultaneously or repeatedly too quickly since I wasn't actually looking at them while fiddling. It's the only thing I can think of, though I've looked in the manual and found nothing like this.

Thankfully, it wasn't too early in the morning, but I'd like to figure out why this happened so I don't do it again. Anyone else have an event like this? Help me not disturb my neighbors any more than I already do...

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[GrabThatBlue]

I know that there is a panic button on your keyfob, but I have no clue if that works while you are driving.

 

[OutofNowhere]

I know that there is a panic button on your keyfob, but I have no clue if that works while you are driving.

I've never tested it, but the manual says it only works while the car is off.

 

[GrabThatBlue]

I've never tested it, but the manual says it only works while the car is off.

Also, this car is very sensitive with low battery power and can do a lot of strange things.
But to be honest, this is the first time I heard about this one.

If it's the low battery thing, you might check for any DTC in Forscan if you have the tool.
If not, it's very handy and should be in posession of every Mustang owner.

Do you have anything aftermarket installed? Maybe a tracker, or alarm or anything else?
I remember some person here bought a brand new Mustang of the lot, but got some device plugged in his OBD port.

 

[OutofNowhere]

Also, this car is very sensitive with low battery power and can do a lot of strange things.
But to be honest, this is the first time I heard about this one.

If it's the low battery thing, you might check for any DTC in Forscan if you have the tool.
If not, it's very handy and should be in posession of every Mustang owner.

I will have a look at the battery level next time I drive out, though I checked it just now and it seems fine. 12v on full accessory power, 14v with car running. Normal, right?

I don't have the scan tool... I should probably get one!

Do you have anything aftermarket installed? Maybe a tracker, or alarm or anything else?
I remember some person here bought a brand new Mustang of the lot, but got some device plugged in his OBD port.

Nothing aftermarket installed, though I did have that same issue with a tracking device installed in the OBD port, even though I specifically told the dealer I didn't want their tracking garbage and didn't pay for it. I had to return to the dealer (3 hours away!) to have it removed, because the service tech at the dealer in my area told me, "It's illegal for us or anyone else to remove that, because if you don't pay your payments..." Such BS!

 

[Wiley Marmot]

I guess my morning wasn't all that bad! That is definitely odd; hope it doesn't happen to you again!

 

[OutofNowhere]

I guess my morning wasn't all that bad! That is definitely odd; hope it doesn't happen to you again!

I did just have it at the dealer for an oil change, so if it does happen again, they're going to see me quite shortly after!

Thankfully, the day improved after the horn incident.

 

[98jfuentes]

same thing happened to me before the first week i got the car. then it didn’t for a year and then it happened again while parked. i think it’s a glitch in the BCM. our vehicles don’t have horn relays anymore. all horn actions are now controlled by the computer

 

[Alan Applegate]

If you think it was the panic button, try it sitting in the car with the engine running and in gear. I've set mine off while putting my keys in my pocket, so....

 

[98jfuentes]

I’m sure it was a BCM glitch. mine went off the same way OP’s went off. i honked and it wouldn’t stop. a year later it went off randomly while parked. i’m pretty sure this is the BCM glitching out. i went through the symptom chart on the workshop manual. all points to a BCM reboot if not then BCM replacement

 

[OutofNowhere]

I’m sure it was a BCM glitch. mine went off the same way OP’s went off. i honked and it wouldn’t stop. a year later it went off randomly while parked. i’m pretty sure this is the BCM glitching out. i went through the symptom chart on the workshop manual. all points to a BCM reboot if not then BCM replacement

So if you're right about this, it's something that would be fixed by the recall that's available, right?

 

[GrabThatBlue]

So if you're right about this, it's something that would be fixed by the recall that's available, right?

Recall is about water intrusion.

 

[steveo1960]

Interesting. My car has been fine but I had a weird thing happen the other day. So I started the car and turned up the heat/defrost to melt the ice on it.
I let it run, with the key fob inside the car while I was shovling snow.
When I finished, about 20 minutes later, I got in the car, grabbed the fob and hit the stop button.

So later in the day I went to remote lock the car with the fob and every time I hit unlock then lock, the car would crank, try to start and then stop.
The app would not connect.
I tried several times, same result.
So next day I went out, opened the car, started and drove it with no issues since.

Kind of weird.

 

[OutofNowhere]

Recall is about water intrusion.

Yes, I'm aware it's about water intrusion, but I thought it was to fix the problem of water intrusion into the BCM module area. Therefore, it seems like the recall would fix this issue, or at least insure that it won't happen again (assuming you don't need a new BCM module), if indeed the horn issue is due to something happening with the BCM module.

I'll mention this to my dealer when I have that recall work done.

 

[bimmerborn]

I second the water intrusion recall idea. Even though they claim it affects exterior lights and turn signals.
https://static.nhtsa.gov/odi/rcl/2025/RCLRPT-25V546-2755.pdf

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