[mikeinut]

My 99 burb did the exact same thing. Sometimes one or two would work and then the next day none of them would work. I replaced the relay that just clicked when I pushed the lock switch and it did the same thing. I found some actuators on Ebay and replaced all four doors plus the cargo door. They work perfectly now. Just a note, if you have cargo doors, the actuator for the rear cargo is the same as the other 4 doors. There's some good info on here about replacing the door lock acutators. It took me maybe an hour total to do all 5 doors. (I was already familiar with how to take the door panels off) Good luck.