I just bought my second max, it is a 1989 pearl white se when I first got the car the power door lock didn't work at all. I replaced the master window switch on the drivers door and know they are working a little, however the passenger front foor will lock but it will not unlock and if i use the key in the door the only lock that open is the drivers door and then i have to use the switch to unlock the rest of the doors The locks also do not work from the passenger door either

 

do you hear a clicking sound coming from the driver's kick panel? probably your door lock timer.

 

I don't hear any clicking sounds anywhere, but today the locks were acting crazy and locking by themselves if i used the button to unlock the door all door would unlock except passenger door and then they would lock instantly.

 

only later (92-94 for sure, MAYBE 91) had door lock timers
and it's actually just to the right of the steering column

 

i resoldered mine...havent had a problem since !!!