Why would headlights stay on on a 2003 windstar?

Answer 1

You are going to love this "better mousetrap!" The light switch doesn't actually control the lights. There are a series of computer modules involved. When you turn on the switch, a signal is sent to the instrument cluster(which is a computer called a "HEC" or Hybrid Electronic Cluster). The HEC sends out a signal over the data bus network called the "CAN"(Controller Area Network). When the FEM(Front End Module) receives the request from the HEC over the CAN, it decides to turn on the front lights and sends a request over the CAN for the REM(Rear End Module) to turn on the rear lights. So, you could have a problem anywhere from the main light switch, the HEC, the FEM, (probably not the REM-since it's headlights), or anywhere in the wiring! Oh and BTW, the headlight switch is not really a switch. It is more like a position sensor. It sends a varying resistance out to the HEC so the HEC sees what position the switch is in by what OHM resistance it is receiving from the headlight switch, so you could also have a slight problem with a connection somewhere that would raise the resistance of that circuit and make the HEC think that you have the switch in a different position than what it really is in. Don't you just love technology?

Here is a suggestion. You may also notice that the overdrive switch in the shifter handle does not work, nor the compass, rear mirror auto dimmer and the rear side door lock switch on the overhead panel. This is all powered by a fuse (#14 I think). It could simply be a blown fuse which is what I had, but that was just a symptom of a damaged wire from the O/D switch in the shifter handle running down the steering column. I could replace the fuse and it would work for a short while, then blow again. The dealer finally located the worn wire and repaired it.