I did a search and found this post:

How can I Disable the Factory Alarm in a '93 300D?

I disconnected every connection in the passanger floorboard, but it still goes off?? what does it look like? thanks!

__________________
2000 Ford 7.3 Powerstroke 4x4
2006 Mazda Tribute
1983 Black 300 D (donated to charity)
1993 Teal 300 D (160K) Sold
"I love the smell of burnt diesel fuel in the morning, it smells like ....VICTORY"

Semper Fidelis
USMC 1973-1976

It's a long slim black box with Becker markings. Has 2 ~14 pin connectors on it.

Does the alarm sound like the factory horn beeping on and off? If not maybe it's not a factory alarm.

Sixto
95 S420
87 300SDL

yes the horn goes off and on and lights flash, my wife set it off yesterday and the car would not start. I had to drive 30 miles to go look at it and I finally got it to stop alarming after I unlocked passenger door..

__________________
2000 Ford 7.3 Powerstroke 4x4
2006 Mazda Tribute
1983 Black 300 D (donated to charity)
1993 Teal 300 D (160K) Sold
"I love the smell of burnt diesel fuel in the morning, it smells like ....VICTORY"

Semper Fidelis
USMC 1973-1976