I have to disagree with the replies to this post as I have a 1998 RL. I believe the door lock feature became intermittent after an electrical "event" which drained the battery. A number of systems did not work after the battery was restored.
For example, the tilt steering wheel did not automatically adjust when you took out the key. The side mirrors did not respond properly to controls.
I was told to try disconnecting the battery and toucing the battery leads together for a minute to drain and reset all of the systems. This did restore the tilt feature and some of the mirror functionality, but the door locks didn't come back. I think I will try it again as it has been months since I tried it the first time.
-Bob