Car alarm going off

[djc]

So the garage queen is on a battery conditioner that runs 9a-9p. At 6a this AM while in the garage, the alarm starts going off. I silence it with the remote. It goes off again. I can stand there and disarm it and it will go off again in a matter of a minute or two. I disconnected the battery for now.

The battery reads 12.45v which according to the internet is low. It's 1 year old. I'll replace it, but wondering if this is a thing with these alarms due to age. I never had this issue before and have had number batteries age and eventually die. If so, what's the fix? Pull a fuse?

thanks.

 

[FleeMan]

Your battery is fine.

 

[DSG2003Mach1]

i have an aftermarket alarm on my 03 and I unplug the battery tender from the battery harness before unplugging it from the wall it sets the alarm off for some reason. Maybe it's an issue with the charger

the interior lights aren't coming on like something is wrong with a door sensor and it thinks the door is open or something is it?

 

[01yellercobra]

Hi Doug.

Why do you have the battery tender on a timer? Did the alarm go off while it was disconnected? It might be worth checking the grounds. Maybe something is getting flaky and the car is thinking the battery is being disconnected and reconnected. I don't remember my 04 ever going off in that situation, but I think my 01 did. I know my son's car will set the alarm off when the battery is reconnected.

12.45vdc really isn't that bad. But I'd check it after sitting without being connected. Make sure that wasn't just the surface charge.

 

[djc]

i have an aftermarket alarm on my 03 and I unplug the battery tender from the battery harness before unplugging it from the wall it sets the alarm off for some reason. Maybe it's an issue with the charger

the interior lights aren't coming on like something is wrong with a door sensor and it thinks the door is open or something is it?

I didn’t think to check the interior light. I was yanked out of sleep as the other half thought someone was messing with the car in the driveway. I’ll hook it back up and check for that.

The last time it did happen months ago, i thought the spare remote was the source because when I hit unlock to stop the alarm, the door would automatically lock itself.

 

[djc]

Hi Doug.

Why do you have the battery tender on a timer? Did the alarm go off while it was disconnected? It might be worth checking the grounds. Maybe something is getting flaky and the car is thinking the battery is being disconnected and reconnected. I don't remember my 04 ever going off in that situation, but I think my 01 did. I know my son's car will set the alarm off when the battery is reconnected.

12.45vdc really isn't that bad. But I'd check it after sitting without being connected. Make sure that wasn't just the surface charge.

Hey Bob,

I have it on a timer because I’m now old and don’t like things like old car batteries charging overnight lol. I didn’t think to check it when disconnected but will. Good call on the ground.

It doesn’t go off when I hook up a battery, though. I forgot it had one until this happened!

 

[01yellercobra]

It could also be telling you that it wants to go around the block once or twice.

 

[98 svt]

12.45v is definitely low for a "charged" battery.

I notice my alarm (I have a 98) will go off sometimes if I let the car sit and don't open the doors for a week or so. If the car is already unlocked, and I pull the handle it will sometimes set the alarm off. However, it never happens if I just hit the unlock button on the remote before I pull the handle.

 

[djc]

I'm back from my trip. Battery has been disconnected since Monday AM, now Saturday. Meter said 12.59v. I hooked up battery tender and it read 12.59. I don't have it plugged in to charge. Since the BT has a wifi meter to transmit the battery data and it is powered by the battery, not AC, I'm curious what the car battery will read in the AM. Battery seems fine. Has date of 8/22.

Both key fob batteries were well into the green with the battery checker.

Also, now that I have had some time to think and read the manual, this car does NOT have a car alarm. It just has the PATS system which is the key / chip thing. It does not have an aftermarket/dealer alarm system, at least that I know of. No hints of one anywhere.

So that begs the question, why would the car horn BEEP BEEP BEEP like a car alarm is going off? The only mention of this is if one is hitting the PANIC button on the remote which was not the case.

Not sure where to go with this.

 

[01yellercobra]

Might be worth checking some wires for chew marks.

 

[efnfast]

I would try replacing the battery before you start chasing wiring and other possible issues (assuming you've checked the tightness of the power and ground connections on the battery and the ground/frame connection).

My 08 Viper had a ~3yr old battery. Charged fine, tested fine, and seemed fine in all respects, but my alarm started randomly going off throughout the day. I replaced the battery and the alarm never went off again.

 

[9T3SVT]

Time to part it out.

 

[Roush6018]

so you want to know what the fix to your cobra is?

i worked very hard to fix the problems with my cobra swap. i do remember having some security issues and i do know what the panic alarm sounds like on a mustang so i did feel reminded by my car when you have shared whats up with your cobra.

to fix the problem it first needs to be properly diagnosed. set up the car in the condition where the alarm goes off. i would leave the battery tender off. then after you verified the alarm had gone off randomly.

disconnect the battery. remove your air intake and maybe remove the intercooler reservoir. then reach down and locate the wire harness that connects to the ABS module. disconnect the ABS module by releasing the lever that loosens the connector. it only has 1 connector. then reconnect your battery and shut the hood. now try to get the car to set off the car alarm in this condition.

the ABS connector is facing upwards and it can catch some water inside and damage the module in there, it is connected to the battery power and PCM circuit. meaning, it can operate with the igintion off. if your problem goes away then replace the ABS module (this is what i did) or repair your original ABS module's electrical circuit and reinstall the original.

 

[01yellercobra]

Time to part it out.

Coming out of left field....