Chrysler Repair: automatic headlights: 99 LHS, headlights stay on

Question
I have a 99 Chrysler LHS with the automatic setting on the headlights.  We always leave it set on the "automatic"mode. At noon on a very sunny day I parked it,went in a restaurant and saw the headlights and also the fog lights  were on. I waited five minutes and they were still on. I went out ,turned the headlight knob to off and they went out. About two weeks prior to that, we came back from a weekend out using another car and this car had a dead battery (battery 2 years old). Any suggestions on how to troubleshoot this issue? Also, when the lights come on at night, it is only the headlights. This is the first time I saw fog lights on also.  Could it be the switch causing this or the sensor?

Answer
Hi Dave,
There are two automatic settings on the switch: one with, one without, the fogs, so that would explain one point.
There are an array of resistors built-in to the headlamp switch which are connected to the body controller. Those provide the info to the controller as to which position the switch is set. The other part of the system is a light sensor, which is also utilized by the automatic temperature control system. I don't have the body controller diagnostic manual but I suspect that it may be the light sensor that has failed, thus creating the impression that it is dark outside. Is it possible that you have set an opaque object on the top of the instrument panel which is blocking the light? If so, removing that would solve it (perhaps a sunshield on the windshield could cause this? If not, check out the price of the "ATC sunsensor" and consider replacing that by removing the top pad where you will find it underneath (with a hole of some sort in the cover to admit the light). The pad lifts off, the sensor is held by 2 screws. To lift off the pad, use a thin stick to lift each end and release it from a clip, then use a thin stick to lift the rear edge and finally slide the cover rearward to disengage from 8 clips that run across the rear edge.
If the sensor is expensive you may want to have an analysis of the circuit done, following the body diagnostic procedure manual. The fuse that runs the sensor also runs the interior lights, etc. so it is not a fuse issue unless those also don't work. You could verify whether you have 12V on the pink wire at its 4-wire plug. It has three other wires associated with its signal and all are routed to the body computer.
Thanks for the interesting problem. It led me to look into a system which I had not noticed before.
Roland