1997 Buick Lesabre door locks

[Shawn Vance Warner]

I have a 97 Buick Lesabre. The door locks don't work right. They will unlock with the power unlock button on both sides. But they will not lock with the power lock button. The key-less entry also doesn't work because of this issue. They worked fine and then stopped one day. The have power because the unlock function works. Which leads me to believe its a relay or control module or something. Some places suggested the relay was under the seat. I looked and it wasn't there. I called the dealer ship and they said it was the control module. My next question to that is if one module was bad how come it does the same thing on both sides (only the unlock function works on passenger and driver side) Any suggestions on where the door lock relay is and what to try first?