Factory alarm system going off

Back in late July I was at a friends house in Kansas City when my factory Toyota alarm system started going off. However, there were severe thunderstorms with 80 mph winds, so my friend and I attributed it to the wind. Didn't do it again after that.


Well, at least until today. I was enjoying a beautiful walk through an Ophir, Colorado forest when my factory car alarm again started its bs. I was about 700-800 yards away so I walked back disabled it, locked it and rearmed it. Got 400 yards away and again it went off. *Groan*. It was raining slightly, but no wind or thunder. Nothing touching it. No one else around.

Walked back and disarmed it, moved to another location and this time I didn't use the key fob. I just locked the driver door with the key. Got about 900 yards into this walk and here we go again.

This time I went back and unplugged both front horns. Drove to Telluride to use a bathroom and while I'm inside it goes off yet again.

I came out, popped the hood and located a third horn on the passenger side fender well. I unplugged it. Triggered the alarm with my keyfob and just a relay clicking now.

I am utterly baffled what's causing this. Any ideas?


2017 Toyota Tacoma TRD Off Road
6 spd manual
38,xxx miles

 

anyone? please help.

 

Unless you have the glass break sensor or an aftermarket shock sensor, it is the hood switch and door switches (and maybe sunroof?) that are monitored by the ECU. Maybe one of the switches has intermittent contact and needs to be cleaned. First guess would be to look at the driver's side door switch. Does the dash display say anything about where the fault is? It certainly beeps at me a lot and indicates on the panel that the driver's side door is ajar. The Toyota app shows what door or if the hood is open, maybe a couple ways to diagnose in there.

 

Just wondering do u put the key fob back in your pocket when u walk away ? Or does it do it with the key out still . I have set mine off having in my pocket . These key fobs are sensitive. Also u can try to replace the battery in the key fob it might be sending an intermittent signal to the the truck setting it off . If the battery is low .

 

I googled the key fob batt and somebody says a low truck battery can set it off too

https://www.tacomaworld.com/threads/alarm-wont-stop-going-off.102925/

 

I was just going to say the same thing about low battery. Both our Tacoma and 4Runner have done this. The 4Runner drained the battery because we didn't know it was going off. The Tacoma's battery gave out a few months later. It may not hurt to replace that.

 

No aftermarket alarm or sensors.
No dash messages.
Truck battery is brand new (March).

I will try replacing the key fob batteries and see if that fixed the issue.

I did put key fobs in my pocket that day I was walking through the forest in Ophir but I was wear loose fitting pants so I don't think that was the issue.

 

Battery could still be weak even though it's new. A decent backyard battery test would be to leave the headlights on for 10-15 minutes and see if the engine will start

 

Where is your fob when this alarm goes off?

Can't tell you how many times I've set mine off, simply because it was in my pocket, and something else in my pocket forces a pressing of the panic button when fidgeting, especially in cargo shorts.

Oh, you can also "turn off" the fob by pressing the lock and unlock buttons simultaneously. The red led should blink twice, pause, then blink twice again to let you know it's off. If the alarm still goes off, then you know it's not the fob.

 

It won't.

 

You think that still works with modern LED headlights putting a lot less load on the battery? Just throwing it out there, no idea if it’s true or not.

 

Not sure, its just a simple way to make the battery do some work without starting the engine

Turn the key on and turn some stuff on like fan blower and inside/outside lights

Or even better, disable spark or fuel and crank it for 5-6 seconds. See if the battery drops below 10 volts

 

The key fob was in my pocket but nothing else was in my pocket and they were loose fitting pants. So they weren't pressing on anything.

 

Shop called today. It turned out the sheathing for the wire on the door sensor had rubbed through and was making contact with metal causing it to randomly go off. They got it fixed and it's ready to be picked up.

 

Man, I know this post is over a year old, but I have a 2019 Tacoma TRD Sport, and the same dang thing is happening to me now! It started late fall 2024, when all of a sudden the alarm would go off, of course, disturbing everyone in the neighborhood, including me! I've tried doing everything and cannot find what is going on. I just want to disable it, but I didn't want to just unplug the horn. THEN I saw this post where you mentioned there being a horn on the passenger side footwell! So just to clarify for me, is that particular horn, exclusively for the alarm system? I mean, that would be great, and I can just unplug it! I just want to keep my regular truck horn, but I do not want any alarms going off! Please let me know. Thanks!

 

so this turned out to be a short on the wire of the driver side door pressure sensor. It was grounding out on metal causing the alarm to go off.

Pic is from google


There is a third horn on the passenger side fender. It is factory.

 

Thanks for this pic and info on the horn. I am still having the problem, but when I take it in to my local mechanic for regular oil change, he said he would hook it up to techstream and see if there is anywhere in there to disable it. In the meantime though, i am going to check out this door sensor you posted a pic of. Thanks so much!

 

Unplug the two front horns and the horn on the passenger side fender. All three are in plain sight. If the alarm still goes off, chances are you have some sort of aftermarket alarm system and that's beyond my expertise.

 

I KNOW it is not an aftermarket system because it came on the truck from the factory with this installed. I will post a pic of the window sticker that I still have on the windows of the truck, just as they came. It is called the "Toyota Auto Alarm", and it is also listed on the window sticker that came with the truck, although I don't have a picture of that at the moment. But if it has its own horn that is separate from the regular horn that come on the truck, then if someone can tell me which horn is dedicated to the factory alarm system, I will just unplug it and be done with it. It is still going off, and waking up the neighbors at all times of the day and night. Very frustrating when I have to keep telling the neighbors that I am "sorry" and can't do anything about it! Thanks so much!
I don't know why I have cross-out lines in my text, but I did not put them there, in fact, I wouldn't even know HOW to!

 

Hi there. I know this is a somewhat older post, but for InfernoTacoCO, I would like to say thank you! yesterday I went out there and found the additional horn that as you mentioned, is on the right side under the hood, by the right side fender. Although it was somewhat difficult to figure out how to unplug the plug, I finally did so and taped it up to protect it. A couple of days before, the dang alarm went off again at 11pm at night, with nobody messing with the truck or anything, so once again, my neighbors were pissed! I had not done anything because I was just wanting to disable the alarm somehow, but except for searching around techstream for it, there was no other solution. So I just unplugged it yesterday. I have not driven the truck since, so I don't know if any lights show up or anything on the dash, but I think this will do just fine. thanks so much for pointing me in that direction of where to locate the additional horn for the security system!