Anti theft alarm trips for no reason

I have a 2001 SEL with 101K that has developed an erratic problem of having the anti theft alarm go off for no apparent reason. All doors will be locked in a parking lot and it will sometimes just trip for no apparent reason. After gong off for awhile, it will stop for 5 -1 0 minutes and then usually trip again. I assume this would continue if we let it go without unlocking the car.

It also has the keyless entry and door keypad. When locking, the sequence is correct (lights flash, horn beeps) as stated in the manual.

I have cleaned all the door contacts that I can find and replaced drivers lock actuator as it seemed weak. At this point, we have just stopped locking the car as I am not aware of any way to disable the alarm, but still be able to just lock the doors.

Any thoughts are appreciated. Thanks.

Phil Mazza

pmazza,
Have you found any solutions to your problem yet? I too have a similar problem 96 Windstar LX with keyless entry and keypad. If I lock the door with the code on the key pad or if I use the remote and walk away in about 1 minute the alarm goes off. If I lock it with the remote or keypad and then turn the key at any door unlock and lock again the car stays locked no alarm. I too have cleaned the door contacts, have no lights on or door chimes going off. All seems to function normally. One question. How is your ignition switch? Are you able to remove the key or start it without the key? I think the problem with mine may be the switch. Try unlocking and locking yours from any door and see if the alarm goes off.

I have not really found the true solution - I suspect it has to do with the two PCMs inside the vehicle losing communication between them. There appears to be a 'heartbeat' signal wire between them that is part of the anti-theft system.

My workaround that so far has been successful: Disconnect the antitheft switch connection on the driver's side lock mechanism. We lock the driver's door manually as we get out - using the key fob still results in alarm tripping (I suspoect since it activates the anti theft via the RKE module under the dash). Not pretty but it works.

Phil

Pmazza
Do me a favor and try locking the doors with either the key fob or the touch pad and then unlocking the door with the key and then locking with the key again and see if the alarm goes off.