Chrysler Repair: headlights wont work; Minivan, fuse box, multifunction switch

Question
hi,
i have a 2001 t&c and the headlights have been giving me trouble. first only one headlight would come at a time. by holding the multifunction switch on high beam, i could use both lights. after checking fuses and bulbs i took it to a shop and they said it was the Front Control Mod. anyway they did something to make it work but that lasted a week. I think they reset the BCM. later i got a used FCM put in and for a week the lights worked and then back to one at a time or working while holding the multifunction switch. so now six months later my lights wont work at all! a few days ago i banged on the passenger light and it came on but only for a few minutes. i even wiggled the fuse and relay box under the hood one day and one light came on but that didnt last either. What could be the problem? I'm thinking the switch or a wire? Every other light works including interior, parking, turn signal, etc. except the headlights. Where is the bcm and how do you reset it? At least this might help me for a few days at a time until i can get this solved. Thanks.

Answer
Hi Alisha,
I wonder how things worked out with the headlamps? You can report back if you like by the 'thank/rate' tab below, without having to wait for me to be 'available' to take a question. While you are there, if my answer was helpful I would appreciate a vote of 'yes' for the 'nomination to be expert of the month'. I am in a close race for that honor so every vote is helful. Thanks in advance.
Roland



Hi Alisha,
With that complex history there are several possibilites. The one side only behavior would not be due to the bcm as that controls both side voltages simultaneously.
The one-sided problem has to be related to either poor connections at the fuses in the box that is under the hood, or a poor connection between the bulb socket's black wire and the place where it is attached to the body (for the return path of current back to the battery, located in the cabin at either the left or right front corner of the footwell where there is a multiwire common grounding point).
The both side no work problem could be the headlamp switch itself, the body computer, or the connection of the body computer to the low beam relay (or the relay itself) or from there to the fuses in the fuse box under the hood.
The only way to get to the bottom of this problem is with a voltmeter and a circuit diagram. You also could use a simple neon 12 volt test light to trace for the presence or absence of voltage at any given point. I would start with fuses 4,5,6,7, in the box under the hood. Those fuses feed the head lamps their voltages (one fuse for each filament). I would test the fuses to see if when you have the head lights on low and then on high beam settings, which of those fuses show voltage and which do not. Once that is determined we can go on further. You measure with the voltmeter or the bulb tester by placing one of its wires on the fuse of interest and the other on the - post clamp of the battery which is nearby (or if the lead is not long enough placed on any shiny structural body or engine surface to which it will reach). Make sure that you have the ignition switch in the "run" position (the engine doesn't have to be running however).
The bcm is under the dash attached to the rear side of the fuse box. It is not something that "resets". If you have had any history of water leaking from the windshield and dripping on the fuse bos/bcm unit that could well be the cause of the problem. We'll deal with that issue after you do the fuse measurements, if necessary. But tell me if you know of such a history.
Let me know the results by using the "thank/rate" tab below to get back to me, without having to wait for me to be available to take a new question. There is a space for comments to which I will reply.
Roland