Car alarm (horn) goes off when connecting battery

[fourfive]

I believe I have a dealer installed car alarm with the red push button to the left of the steering column. Anytime I reconnect my battery (positive then negative) my alarm (horn) starts going off. I can hit the unlock button on the remote to turn it off & everything will function normally. This has always happened since I've owned it & I'm the 2nd owner. Aside from permanently disabling the alarm, is there a permanent way to fix this issue?

The alarm problems I've read about weren't exactly like mine but here are some of the suggested solutions:
1. Reset the alarm (I forget the exact steps). I haven't tried this because pressing the unlock button on the key fob would stop the alarm & there weren't any other alarm issues after that. But, is resetting the alarm supposed to be a permanent way of addressing this issue or is this only intended to correct the alarm if it wasn't functioning normally?

2. Make sure all doors are closed & no lights on inside. I've made sure of this & my alarm would still go off when I reconnected the negative terminal.

3. Before connecting battery, put the key in ignition & turn to on position (without turning on engine), then connect battery. I haven't tried this yet.

 

[firemanj92]

Most if not all car alarms will sound when reconnecting to the battery both factory and aftermarket. I have not come across one vehicle (no matter what brand) that does not do this even attempting some of the solutions that you have provided. I believe it's just the nature of the beast.

 

[BrianSD_42]

On my 97 Limited with factory/dealer alarm when I remove the battery and reconnect it will not go off unless it was armed at the time of the battery disconnection.
.

 

[fourfive]

Most if not all car alarms will sound when reconnecting to the battery both factory and aftermarket.

I was wondering about that but I don't remember this happening on previous vehicles I've owned that had alarms. ....but my memory can be somewhat selective so it's possible that it has happened with other cars I've had & just forgot about it.

 

[Acorn22]

Mine does that too, and it would scare the hell out of me before I started pulling the horn fuse before I reconnected the battery. Haven't found a way to completely disable it yet though...

 

[96RedRunner]

Neither my 96 or 01 do this, I do remember reading in FSM or op instructions for RS systems to have it disarmed when messing with battery, what I do on my Audi also.

 

[gamefreakgc]

Mine does that too, and it would scare the hell out of me before I started pulling the horn fuse before I reconnected the battery. Haven't found a way to completely disable it yet though...

This is your best solution. The horn won't sound at least, giving you time to reset the alarm and then hook up the horn again.

 

[fourfive]

On my 97 Limited with factory/dealer alarm when I remove the battery and reconnect it will not go off unless it was armed at the time of the battery disconnection.
.

When you say armed, do you mean if your doors were locked before disconnecting the battery the alarm would sound when reconnecting it?

 

[Zelos]

Most if not all car alarms will sound when reconnecting to the battery both factory and aftermarket. I have not come across one vehicle (no matter what brand) that does not do this even attempting some of the solutions that you have provided. I believe it's just the nature of the beast.

I wonder how much merit there is to this since the only time I've replaced or disconnected batteries for service on a number of vehicles with factory or aftermarket security systems and the alarms don't normally go off. I just replaced the battery on the '00 4Runner with the factory system without a beep.

Are you referring to alarms going off when the security system is armed and the batteries reconnected?

 

[BrianSD_42]

When you say armed, do you mean if your doors were locked before disconnecting the battery the alarm would sound when reconnecting it?

On my alarm the doors being locked (eg using the door lock button on the inside door) does not activate the alarm. My alarm is only activated by using the key fob.

So if I use the key fob to arm the alarm which will also lock the doors and then I disconnect the battery, yes it will cause the horn to go off once I reconnect the battery, assuming a car door is open at that moment. All I have to do is simply click the key fob and it is disarmed.

Now if the alarm wasn't armed then no horn (eg alarm going off) when I reconnect the battery, whether any doors are open or not.

You can also override the alarm as it is going off by inserting the key and going full fwd and back two times in the ignition.
.

 

[fourfive]

This is your best solution. The horn won't sound at least, giving you time to reset the alarm and then hook up the horn again.

It's a good way to work around the issue but wondering what is causing it to happen. My friend has a 99 & I don't remember his alarm ever going off when we would reconnect the battery after working on it. I don't remember if his was a dealer or factory installed alarm but thinking it was dealer installed.

 

[Zelos]

It's a good way to work around the issue but wondering what is causing it to happen. My friend has a 99 & I don't remember his alarm ever going off when we would reconnect the battery after working on it. I don't remember if his was a dealer or factory installed alarm but thinking it was dealer installed.

Any idea of the make/model of the alarm if it is aftermarket?

 

[fourfive]

On my alarm the doors being locked (eg using the door lock button on the inside door) does not activate the alarm. My alarm is only activated by using the key fob.

So if I use the key fob to arm the alarm which will also lock the doors and then I disconnect the battery, yes it will cause the horn to go off once I reconnect the battery, assuming a car door is open at that moment. All I have to do is simply click the key fob and it is disarmed.

Now if the alarm wasn't armed then no horn (eg alarm going off) when I reconnect the battery, whether any doors are open or not.

That's actually what I meant about the alarm being armed when the doors are locked with the key fob but that's an interesting observation. I'm assuming that my alarm wasn't armed anytime I would disconnect my battery because I don't think I would have ever opened the door to pop my hood then lock the doors with my key fob before lifting the hood but I actually never paid attention to that.

You can also override the alarm as it is going off by inserting the key and going full fwd and back two times in the ignition.
.

Good tip especially since my key fob (or key fob battery) has been on its way out. That would have sucked if this happened without knowing another way to override the alarm while it was going off.

 

[fourfive]

Any idea of the make/model of the alarm if it is aftermarket?

From what I've read, I think it's aftermarket since it has the red push button light to the left of the steering wheel instead of the Toyota Security switch/light but I haven't traced it back yet to confirm.

 

[BrianSD_42]

I should also add that there are probably some differences between my 97 alarm and your 2002. I don't have a key chip, do you?

 

[fourfive]

I should also add that there are probably some differences between my 97 alarm and your 2002. I don't have a key chip, do you?

No key chip on mine.