Hello to the Chrysler Forums! I came across this thread because I am having the exact same problem with the alarm system in my 1990 Chrysler New Yorker (3.3) above. It cranks, and sometimes it will start for about two seconds, but dies immediately. When in the car, there's a dash light stating the alarm is armed. I know this is an old thread, but I will post here because it already has all the information in it.
The car will not start, because the alarm system has it shut down somehow. I've tried all of the solutions above, and more, but none of them work. I have tried disconnecting the battery, unlocking the passenger side door (along with the driver's) repeatedly, and everything else I can think of. The previous owner also told me that there was a way to disarm it by unlocking the passenger door, but I can never get that to work.
I'm hoping that someone here will be able to help me. I have got to get this fixed. Any help or suggestions will be greatly appreciated. Thanks in advance.