I am having the same issue with our 1997 2.5 TL. Seemed to start when the battery got low from sitting a couple months while my son was at basic training. May be tied to alarm system which I have yet to figure out how to enable/disable. Neither key has a fob, only the key. Our TL constantly locks and relocks every few seconds. Once started the interior and dash lights blink on and off at nearly the same interval as the locks. Leave the door open and the exterior hazard lights blink on and off. Its as if the alarm system is controlling it. I did pull the 20 amp fuse for the door locks so it wouldn't drive me crazy. That didn't stop the other issues though. When the door locks are actuating, I can hear what sounds like a relay switching back and forth under the dash near the steering column. Any help someone can provide is greatly appreciated.