I've owned since new a 98 E-320 - 125k miles. It still looks and runs like new but ... took a long drive last Monday and all of a sudden the door locks popped up. The switch on the dash has a small red light in it which I never saw go on before but it's on now. Stopped the car at a rest area and the car wouldn't lock ... and the fog lights came on (the switch was off). Started driving again (no motor/trans problem) and about an hour later the turn signals stopped working and the interior lights came on. Finally reached home. I neglected to mention that the dog was in the back seat and spilled about a pint of water onto the seat ... the battery is under the seat. I pulled the seat and saw some moisture in the bottom of the battery compartment. Fog lights still on....disconnected the battery ..removed and replaced the fuses (all were good) and used a fan all night to dry everything. Next day went to the dealer and asked what they thought .. the had a blank stare .. said it could be corrosion (I saw none) ...said it could be the ignition switch ... said to try both keys as they have computer chips and I did that ... no change....said that if I brought it in they would begin with changing the ignition switch and then start changing things as they traced it ... which gave me no feeling of confidence.
Today .... it seemed to be working ok with only one problem .. the door locks. So I left the battery hooked up ... about an hour later..just sitting in the garage .. the fog lights came on. I disconnected the battery ... scratched my head and joined this forum to ask for some suggestions. Thanks.

 

the door locks could be just a broken door jam switch. there is a switch at all 4 doors. if the switch breaks it will think the door is open thus turning on the intrior lights and unlocking the doors. check the switches at all the doors. usually under the strikers. they crack and fall into the body.

 

Sounds reasonable .. I checked the switches, they don't appear broken .. push in and spring back fine ... do I need to remove them and check the wires wiht a meter to see if they are actually working? Any hints on removal? Thanks!!