Continuous beeping sound and doors locking by themselves
 

2001 Ranger XLT, There is a beeping sound continuously going off, the small red LED next to the radio flashes?? and a clicking sound is coming from the fuse box. Under the hood.. The horn used to continuously beep as well but it burnt out.. Thought it was auto theft but the truck starts fine, I replaced the transceiver anyway and still going off. The sound continues even when the key is out. and you exit the truck, the lights flash in front as well, sometimes the door ajar light flashes. and dome light flashes as well. Its crazy. Tried door sensors next, lubed them and nothing happened, so I replaced them both, without luck. After a while the doors lock automatically and the sounds stops, but it randomly starts up again. The doors will lock automatically even if the truck is running and your not in it, found this out the hard way, got locked out of a running truck.

There is a small plastic box with electronics and a red and green LED under the drivers dash and the LED's are flashing as well. This box is molded with number ALA95. maybe an aftermarket alarm?? Its merely tied to a harness with a cable tie and has a small red plug. Its wires appear to enter one of the harnesses. This box has a min-max adjustment on it that can be changed with a straight screwdriver. Don't know what this part is but was going to replace this next if I can figure out what it is??

This is an extended CAB truck and one of my back doors wont open because the ends of the cable is shot, replaced the ends on the passenger side so it functions. Wondering if there are switches on these back doors as well? maybe one is stuck? Or is this an alarm issue? Want to trouble shoot this as much as possible before I take it to a shop to eliminate the problem or at least some labor troubleshooting?

Any help appreciated.......Learning a lot about this vehicle.

It does sound like an after market alarm system. I had one on my '95 F150. If you trip the alarm or the vehicle battery died or was replaced, the alarm would go of with lights flashing and horn blowing.
To reset the alarm without the key fob, I had to insert the key in the ignition, turn to ON then flip a toggle switch that was placed below the steering, near the hood latch. So look for such a toggle switch
and try what I described.

Thanks for the input, I already removed the panel below the steering column in order to replace the key transceiver and didn't see any switches just that black box with flashing LEDs on it. Tried to just disconnect it but no change in the situation.
Took apart the latches to the 2 back doors yesterday and they do have door open sensors, lubed them and put back together but still flashing. I'm about out of options, relay under the hood? seems to be clicking during the noise.

Eureka, pulled on all the wires under the dash and sure enough there was a loose one, pulled it out and it had a toggle on the end, followed your procedure and the sound stopped. Hoping its permanent. Would like to get rid of this system entirely!!
Thanks after trouble shooting many things all I had to do was flip a switch I didn't know existed, lol.
Win.