F350 Econoline Van electrical system

I hope someone can help me. I have an 87 E350 Diesel Econoline Van, and the automatic locks are trying to lock themselves, and running my batteries down. I thought I had bad batteries, but they checked out fine. I heard a noise outside the van and it was the locks trying to lock.
I have to jump my van if it sits for more than 2 days. My fuse box is worn so I do not know which fuse go to what. Please I hope someone can help me. Thanks, Linda

Usually the locks are not supposed to lock on this model by themselves, the newer models 2000 and up would if the security system detects the vehical in motion or if the engine is running with the key in the on position....the ignition "senses" the idle and with the computer telling the locks to armed (lock the doors) The way to find out WHICH door the culpit is, well is to leave a door open and watch the locks armed themselves, the door that doesn't lock is ok, while the door that does is the culpit. usually there is a short in the circuit that controls this lock on that door, it could be in the WIndow/Lock pad making the lock circuit close. The keypad is usually on the drivers door, but there is also one on the pass side, but usually its the drivers keypad that control the locks is shorting making the lock engaged..constancely....do you hear any sounds after the lock has locked? The fusebox usually will have the windows/lock circuit on one circuit, so if you have electric windows, this could also be the gremin that is stealing your battery power, or your battery could be weak and you have some other security features you may not be aware of....