Courtesy lights will not shut off. Car has illuminated entry which I guess gives theater dimming to interior lights. I can not get them to shut off and I can not find any switch on the door to check. They will shut off after 10 or 15 minutes so there must be a timer to override the lights after a certain length of time. This has happened once before and it corrected itself. The only thing different this time is I ran it through the car wash - maybe something got wet but I do not know where to start looking. Anyone have any ideas on this? It is a 99 Bonneville.

I know it sounds strange, but try disconnecting the battery overnight to see if it will reset the computers in the car. Then hook it back up in the morning. Sometimes I've had luck in doing this on other cars.

Check to see that all the doors and trunk are firmly closed. The interior lights will stay on for that 10-15 minutes when a door or trunk is left open.

I was going to say see if the interior light switch is still on.

I'm with smellbird on this. In simple terms it seems that a "door open input" to the controlling module (Drivers Door Module, maybe) is holding the interior lighting relay picked up and I think there may be another protection feature that drops the interior lighting relay 10-15 minutes after ign. switch is turned off. Not real sure about the 96-99'* though. Also the actual door switches that indicate a door open I think are integrated into the door lock actuators which you can't physically see. (internal to door)

doesnt the twilight sentinel cover this? Make sure its turned all the way down.

A guy I work with had this problem on his Grand Am, until he replaced the alternator... Weird, huh?

sounds like the interior dimmer module...ive replaced these on other make cars...

Twilight Sentinel controls exterior lighting.

I don't think that'* weird at all. I had a few little funny problems like this when mine was failing. Including a misfire due to undervoltage on a weak coil. It improved dramatically with the new alternator, then the new coils cleaned the rest of it up.

A good voltage check would be in order. From the battery before you start the car, and idle charge as well.