We recently bought a '99 Cummins Diesel 2500 Laramie Ram. My mother in law went to start it while we were out of town, and she said it wouldn't start and that the alarm started going off. We don't have the FOB, but the alarm eventually stopped on its own.

When I went to start the truck a week later, the alarm went off when I opened the door and the battery was clearly dying (no lights, wipers crawling across the windshield). I charged the batteries to full charge, but the alarm seems to have some sort of immobilizer because nothing happens when I turn the key to start it.

I don't believe it is an aftermarket alarm, but I don't know for sure.

I did some googling with little luck, and I don't know much about cars, not at all to be honest. So I turn to you Dodge Enthusiasts! Any advice?

 

Look around for a button either on the brain for the alarm or hidden close by to the driver....fuse box, the dash, pillar, under dash, etc.

If you find it connect the battery and turn to key to on, then press the button and alarm should go off. You could look under dash and remove the brain disabling the alarm

 

if it isnt aftermarket, try locking and unlocking the drivers side door from the outside with your key, try the pass door if the drivers doesnt work. if its factory the key should shut it off when u unlock the door, and it wouldnt be the first time ive seen a car that didnt work on the drivers side, so do try the passenger door. if that doesnt work it is more likely aftermarket and then it can get a little hairy. its not always as easy as just unplugging the box.