Can the alarm drain my battery and is there a kill switch for the alarm?My car won't start but it's a brand new battery in it. When I open the door the alarm goes off for a while then stops. I don't have an alarm key. It wont start with a jump either.

Make sure your Battery is fully charged. A partially charged Battery can make the alarm system malfunction. Also, make sure the
regulator is charging the Battery. Some key alarm systems can
and will drain your battery if the Car is rarely driven especially
if there is a ignition kill switch wired into the system. The key alarm
system on my Mercedes 560SL used to drain my battery whenever
I didn't drive the car enough.

turn ignition switch on position for 20 seconds then try to lock and unlock doors.if you have sun roof open sun roof fully then close sun roof fully. then switch off ignition switch then try to start.

yes over time it will kill the battery
check the door switch
some head light switches have a position that keeps the interriier lights on

You would have checked the charging system before replacing the alternator, so I will assume the charging system is good.
If the battery is being discharged overnight or over a few days, you would need to disconnect it and check every circuit on the truck to find the drain.

First, Have your Battery tested. The Alarm systems in Ford made Products are very sensitive to Voltage. There are 3 systems in the car which interrupt power, the Alarm system (horn honking) and the Battery saver and finally the starter interlock system.

The Alarm system will do several things to disable the car from starting. It will reduce the voltage to the starter to prevent the engine from turning over. Some will even kill the ignition system so that if the starter is jumped, the car still won't start.

The Battery saver will disconnect any system to prevent discharge below a minimum threshold. Unfortunately, when the Alternator is working extra hard to charge a really bad battery: it will disconnect the charging circuit because it reads the Draw going to the Alternator to produce the power as a parasitic drain. Even at 70mph I have seen the charging disconnected and the vehicle coast to a stop when the electric runs out.

The last system worth mentioning is the Starter interlock. Under the dash and at the top of the Brake pedal lever is a switch. When you press the brake pedal, the switch allows the starter to crank provided the shifter is not in D or R. Drivers feet routinely hit this switch and either move it or break it. When it breaks it can short and drain the battery.

As you mentioned a Random problem, the Brake switch can shake to create a random problem if it is loose or broken. Your rear brake lights can be affected.

With the horn honking, at least part of your problem is the Alarm system. You can have a bad ignition switch too, which reads the keychip to disable the alarm. Your keychip may be bad and setting off the Alarm.

I had a new Lincoln myself which set off the Alarm randomly. I actually slept inside the car one night so I could turn off the alarm in the Apartment complex parking lot. Did'nt know if it would start again if the battery was disconnected and then reconnected. The Battery was shorted with less than 1000 miles on the car. It was a factory defective battery less than 3 months old.

But your car has many years and miles on it so it was worth mentioning the wear items. I hope my solution is helpful.

Hello! The drivers side door lock/unlock switch is more than likely defective...Having said that, the alarm system on Jeeps are a constant problem...To disable the system requires removing the drivers door panel and cutting the Light Green/Orange wire at the switch...And installing a 465 Ohm resistor...Not something done without the necessary skills...
I would have the vehicle towed to a Jeep dealer and have them test the drivers door switch and disable the alarm....Guru...saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

Open the door, the alarm will sound , go under your dash, normally installation techs will install a kill switch or alarm override button either in the drivers side kick panel to the left of were your left foot rests or inside the fuse box panel, under the steering column or by the center column somewhere but most likely the drivers kick is the spot. So open the door and find the kill switch or override button and put the key in the ignition turn it to the on position without cranking and press or toggle the switch after you turn the key, this should override the alarm and let you start the vehicle, otherwise you have to remove the alarm main fuse from the brain and rewire your starter kill to factory so that you can start your vehicle normally again until an alarm tech corrects the alarm wiring.

Good luck my friend, hope it is helpful.

Do you have a chipped key {small black thing in the middle of the key} if not you need to take your registration into the dealer and order a new key.

try unhooking battery cable. hook back up and use key remote to unlock car and try to start if no remote use key to unlock