factory alarm system question

I have 1991 Chrysler New Yorker(3.3) with a factory alarm system. The alrm is armed and cannot start the car. I've tried diconnecting the battery and that does not help. When you try to start the car it cranks, and sometimes it will start for about two seconds. When in the car, there's a dash light stating the alarm is armed. I do have a key fab that doesn't work. And yes, I have tried the key in the doors, but that doesnt disarm the alarm. Can anybody give me any ideas on to disarm this factory alarm? I hate to junk the car it only has 42,000 original miles on it. I would appreciate any help.

scott

I have the same problem on my 1992 new yorker fifth ave.
 
The guy that sold me the car said to disable the alarm you have to unlock the passenger side and not the drivers so I've been doing that
 
then I disconnected my battery the other day and now when I start the car the engine doens't go and the alarm goes into action again
I can't fix this problem

on my 93 fifth avenue, if I unlock the driver's side first, the alarm goes off. If I unlock the passenger's side door FIRST  WITH the key, I don't have a problem. the previous owner said the same thing. Once I have the passenger's side opened, then I use the door unlock button on the passenger side to let me in.

have you tried locking & unlocking the doors with the key - and NOT the door lock button ? You
MUST unlock the PASSENGER door FIRST !! Good Luck !!