Disarming Factory Alarm Using Door Key

Hey Everyone ! I cannot disarm my factory alarm using the key in the drivers or passengers doors. I am using a full key turn as instructed but it will not disengage the alarm. It disarms using the keypad without any hesitation. If the keypad ever gives it up, I am screwed as I'll never get this thing started. I have the big service manual from Ford but it isn't much help without a code reader. Maybe both key sensors are shot in the cylinders but I doubt it. Does anyone have any theories? If so, in anticipation to your responses, I remain.
Thanx

Okay, we need to know what year and model please?

Sorry all. It's a 1995 Continental with of course, a factory alarm.
Thanx

I looked in my shop manual, if the remotes and keypad on the door disarm the system, then the problem is probably in the LCM. I dont think that both door lock switches are bad either.

Do the remotes as well as the keypad on the door disarm the system? If so, I would get the LCM diagnosed with a scanner before replacing it.

LCM=LIghting Control Module

I have same problem and found out when i bought car i only have valet key and not original and only original not valet will shut alarm off...Good luck...you will probably have to order a key...thank god i can still start the car i only have to worry if the alarm goes off and i can't get it off if key pad dies.

John 98 Lincoln Conti

I BET THATS IT !!!!!!!!!
Thanks John 98 lincoln conti.
I did learn that my key that came with the car when I bought it is not the original key for it. It never occurred to me that I would need the original to unarm the darn thing. I've actually tried to disable the alarm but my Lincoln dealership doesn't know how.
I know thats got to be it.
Thanx again
Brad 95 lincoln conti

No problem best of luck. Also note you can buy original key from dealer and get it programmed for about $50