If you set the alarm with the key fob before the battery went dead, I think you need to DISABLE the alarm with the key fob as well. Even if you didn't set it with the key fob, you may need to use it to reset everything because who knows what happened when the juice ran down.

If it's anything simple like that, it could be that you have a problem with your ETACM, the module that controls the alarm. If you connected the cables backwards at any point, it could have damaged it.

 

I'm almost certain I did enable the alarm with the fob before it went dead. I've tried to turn it off using the fob, but I get no response from the vehicle when I hit the disable/unlock button.

Any other ideas how to disable the alarm?

 

If you're still under warranty, call Roadside Assistance.

 

I pointed out before that Roadside Assistance couldn't figure it out. My next step was to have the vehicle towed to a local dealership.

The service department wasn't open, but i was hoping a dealer knew what was going on... sure enough, one guy had been through this before.

Like Doohickie said about the battery dying when the alarm is armed, you must reset/disarm the alarm. Here's how you do it if the car doesn't respond to the fob:

1) Connect power source to your dead battery (charger box or another battery), the alarm will be going off loudly and very obscenely.
2) Turn the key to the ON position and simply listen to the alarm go and go and go....then it will stop after about 30-45 seconds. AFTER IT STOPS, leave the key in the on position for another 30-45 seconds.
3) After the key being in the ON position in silence for 30-45 seconds, turn the key all the way to the left, then crank it all the way into the ignition position.

Worked fine after all this.

Thanks for your help.

 

I had the same problem. I have a 2010 Hyundai Elantra and the last time I drove it and parked in the driveway, it was fine. Went out to start it and it was completely dead. Put on the battery charger and the car alarm started going crazy, so disconnected it. After reading the instructions here, I first put the key in the ignition and turned it on. Then I connected the battery charger and the car alarm did not sound off. So, I set the charger to trickle charge and will let it sit overnight. It's possible the battery is completely dead, as it is the original battery an is 13 years old.

 

I am stuck with the same problem and been trying to "reason" it out. Thank you for this solution and the clear atep-by-step description. I don't want to annoy the neighbors, so I'm trying an approach. I have the battery disconnected and the charger on it. When it's pretty well charged I'll hook up the cables and see what happens. If the horn is still blowing I'll pull the horn fuse and go through the procedure you describe. I'll update you on results. I have no idea what killed the battery, so of course I will still need to check out the health of the battery and alternator. I may skip the arming function in future, cuz I dowana ever get stuck like this on the road.

 

I get this sort of thing at work all the time. Hook up the jump box or other car. Then use the key fob to lock and unlock your car. If that does not work, use the key to lock and unlock the driver's side door (with all doors closed). When a battery gets below a certain voltage it really screws with the alarm system.

 

Thanks for the good information. My daughter's car has had to be jumped like 4 times in the last few months. This time the alarm horn started sounding as soon as there was power to the battery. Knowing I probably won't have to take to an auto electric guy is great. I'll be trying guybo's method first so I, and my neighbors, won't have to listen to the alarm for a minute. My second try will be the method described by sage1166. Thank you for starting this thread. This might be a good reason to invest in an aftermarket alarm system, if this is a semi common problem in the Elantra. I'll update with my success, or failure later.

 

The alarm will siren up as soon as you apply power to dead battery BECAUSE hood/bonnet is up. There is a small button right next to the power steering reservoir that tells the alarm that someone is under the hood... push the button before applying jumper cable to battery. Then promptly disable alarm/unlock with keyfob remote... Then you have no alarming the neighbors or terribly loud siren to deal with waiting for system reset. PS... The horn fuse does not connect to the alarm siren...

 

hi

 

This worked like a charm for me!!!

 

Help! I believe I have a parasitic draw from my alarm system that is draining the battery. How hard is it to disconnect alarm? Aftermarket alarm on 2009 Santa fe