Alarm when my car is off and closed the alarm souds

this could be the door striker plastic has broken off this is the post sticking out of the frame when you close the door the lock closes around the striker to keep the door closed this striker could also have moved slightly from opening/closing the door thousands of times try this open your windows get out close all doors set the alarm wait a minute then try to lightly move the door/s in and out by grabbing the door at the rear part where the door locks to the frame where the striker is if it has any play in it the connection will break and this will make the alarm think the door has opened and the alarm will sound getting the door to close tighter will stop it from happening this is also true for the trunk if you press down on the trunk or your able to pull up on it a little the same thing will happen its loose and will trigger the alarm if this is not the problem I would then go to the door pin switches that turn the lights on/off when the door is opened/closed especially if the alarm was aftermarket installed but you can be sure the alarm thinks that something is opened and the door/trunk/hood are the only places that they are

check your batteries. the car battery and your key fob batteries. if they are low it can cause your alarm not to function properly.

If the windows open or close if you hold the key in open or close position then the alarms working .You could break open a window no alarm but the car will not start owning to immobilisor .Not all cars have the type of alarm your thinking of ,and dont bother fitting one of these viper things as i get loads of questions on here when they go wrong which is often owing to the cheapo microcircuits used from china .

Use remote to turn off alarm with all doors closed. the other is to have all doors closed and locked, then unlock from drivers door and turn key twice simutanously. Your third is with the ignition switch depending on what type of alarm it has. I.e., factory or aftermarket.

Check all door switches. One of them is not properly closed even when the door is closed. There is one in the front bonnet and maybe one for the rear boot/door. If one is shorted to ground, the alarm will go off.

your car have a soon roof ? check if safe close

Try opening the drivers door, leave it open and then hooking up the battery. It worked in my case.

If the alarm keeps going off constantly and the remote has no influence on the alarm its most likely a connection problem. A hyundai dealer might be able to fix it but since you can start the car something you might be able to try is....
Check and make sure the remote battery is in the right way. Make sure all of the doors are closed, the trunk is closed, open the hood, connect the battery, close the hood all the way and try to lock and unlock the doors. Hope this works but if not, sorry it didn't work.

Try to check if all doors are close properly and also check the battery of the remote of your alarm because if the door is not close properly the alarm will not turn off.

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