Power Locks Acting Funny

Did a search and seems that most people have fuse troubles...not the problem here. Also, this is on a 1998 4 door XJ. When I mash lock the front 2 doors do not lock 90-95% of the time, but sometimes will. They try to move but don't seem to have enough juice. Recently, the rear passenger one did the same thing, but the rear driver one works fine. What would be causing this?

They have a solenoid that actuates them. They get weak from bad grounds and being dirty. They will start to act as you describe. They need to be cleaned and lubed( I use silicone spray) and the ground points cleaned up and re-attached.

Thanks, I was thinking they may have to be replaced but cleaning grounds and lubing is simple and cheap!

Had the same exact problem on my driver's side door last winter on my '99. Only lasted for a week or so and has worked great since. I think my Jeep just doesn't like the cold. But then again, neither do I.

With highs in the 90's I would be willing to bet that cold isn't the issue