1990 Bonneville SE
ok here is my problem -
once in a while (sometimes once a month, other times once every 2 months)
my driver door lock would unlock by itself. One other thing which may be related
to this issue, I am able to unlock all doors by pressing the unlock button, but
only three doors lock when I press lock, the drivers door always has to be locked
manually . Does anyone know why. Since I purchased the car 6 years ago its been
occuring.

In my SSE, the driver'* door is isolated from the other doors with respect to the lock circuit. There is a seperate relay pair for the driver'* door and a seperate fuse. I'll double check my wiring diagrams tonight to see if the same applies to the SE.

As far as it locking by it self, well that'* a mystery. Perhaps a trigger wire touching metal?

*Edit* Reading is fundamental... Your lock rods probably just need to be lubed

Does the lock move at all when you try to press the lock button? Does it behave the same with both the remote and the inside button?

Yes the lock acts like it will lock (it moves as if trying to lock when I press
the lock button) but it just moves it does not go down to lock.

It sounds like mechanical issues or binding within the door.

You might have two issues here. One, like Fuddy said, is mechanical.

The other, where the door sometimes unlocks itself, happened to me awhile ago. It turned out it was a sticking contact behine the lock/unlock plate.

Thanks for the replies.
Ol'Timer how did you correct the contacts issue? Did you remove them
and clean them or did you replace them?

Wellllll, what I did was take the plate off and gently bend the metal contact further away from making a permanent connection. However, I have found that I must have other issues with this assembly as the problem comes back every few months and I have to "un-stick" the stuck contact again. If I go to a "boneyard" one day, I'll look for a "new" assembly to replace the original unit.