Doors will lock themselves when unattended and not running---even when the fuse is pulled (I know I've pulled the correct fuse because the locks won't work by my pressing the button---Ive not found this posted anywhere but my guess is the BCM just from other things I've read-------Thanks in advance!
Doors lock themselves on 1992 Buick Regal
by sprintman in Moville, IA on October 24, 2009
ANSWER by Oakman on October 30, 2009
From my best recollection your 1992 Buick Regal does not have a BCM. BCM's did not come on line until later in the 90's. If your Regal is equipped with remote keyless entry the problem could be with the keyless entry receiver. Again, as I recall the keyless entry module is located under the package shelf behind the back seat. You could try unplugging the keyless entry module to see if your door lock operation returns to normal. (Less the keyless entry functions.)