car alarm goes off by itself....grrrrr

[LORDY611]

2001 Chevy Blazer with factory alarm. Using the key fob remote, lock doors, forget about it. HOURS later, randomly the horn will honk for about 2 minutes. Of course it happens at 2:30 AM or something equally goofy. The only commonality to the last 4 times it has happened is that it has been cold (10 to 30 F). Nothing mechanical or electrical has happened to it recently. Is it possible that the battery might be going bad and causing this? Any other probablilities?
My daughter has this vehicle at school and I'll keep her from being lynched by her neighbors if I can fix it. :/

Thanks very much for any help.

 

[xtraham]

Re: car alarm goes off by itself....grrrrr

does the horns have a constant blow ? or does it blow like the alarm has been activated ?
I have seen several cars in cold weather blow the horn, but at a constant blow, because the cold will shrink the vinyl on the steering wheel just enough to ground the horn, therefor causing it to blow, also hard wind shaking the car, or the vibration of a loud noise i.e. truck exhaust or boom box cars passing or pranksters can set off the alarm.......

P.S. I have daul exhaust with glass pack mufflers on my old dodge ram charger, at times when I fire it up in a parking lot it will set some alarms off, sometimes as far as about 50' away

 

[rwise]

Re: car alarm goes off by itself....grrrrr

That happened on the S10 I had, the alarm would go off for no apparent reason. Turned out the battery was failing and the alarm monitered battery voltage, seen a drop and went off. Changed the battery and all was well again.

 

[xtraham]

Re: car alarm goes off by itself....grrrrr

Rwise is correct, a drop in voltage will also cause an alarm to sound.........
I have mostly seen that happen with after market alarms, but I suppose it could do it on a factory system also

 

[LORDY611]

Re: car alarm goes off by itself....grrrrr

When the horn sounds, it is not a continuous blast, but typical of what you think of: Beep beep beep about every second or so.
Not sure why I thought it might be the battery also--perhaps I read it on another alarm or Blazer website. It must be pretty sensitive if that's the reason because the truck starts right up every time. I will however check the voltage. Thanks again~

 

[BLU LUNCH]

Re: car alarm goes off by itself....grrrrr

I can set alarms off in the parking lot at work I found out by accident just by TX on my 2 meter ham radio with 50 watts it would set alarms off at 100 feet or so....I still PO the boss, I can see when he is just about in the building and I will key up and set it off and he's got to come all the way back out to reset it.LOL I'm driving him crazy!

 

[rwise]

Re: car alarm goes off by itself....grrrrr

I can set off most alarms with my truck just driving by d

 

[Link]

Re: car alarm goes off by itself....grrrrr

I can set alarms off in the parking lot at work I found out by accident just by TX on my 2 meter ham radio with 50 watts it would set alarms off at 100 feet or so....I still PO the boss, I can see when he is just about in the building and I will key up and set it off and he's got to come all the way back out to reset it.LOL I'm driving him crazy!

Now BLU LUNCH of course is not talking about just keying down on his radio
He was making a legal transmission, per part 15 of the FCC regulations.
Just so happens that his boss has a cheap alarm system that goes off while he is talking. 8)8)

Btw my best is 25 alarms in one parking lot while talking on 144 Mhz at 50 watts. :devil:

That was one of my first thoughts.
It might be RF (radio frequency) sensitive.
A RF choke or two might solve the problem.
Sold at radio schack and other places.

My system is after market and I paid a bit more for it. I can adjust each sensor as I like. With a remote.
IE: as mentioned glass packs and planes flying over will cause it to chirp and flash lights but won’t set off the alarm.
Unless I want it to.
Just lets people know it is armed.
And a couple chirps doesn't bother my neighbors at 2am.