Chrysler Repair: 01 Town and Country headlights, body control module, fog lights

Question
I have a 2001 Town & Country. I have a problem with both headlights not coming on at the same time. When I start the car the left side DTR light only comes on. When I turn the headlights on, only the right side low-beam comes on  When I operate the dimmer switch for the hi-beams, only the left side hi-beam comes on and the right side low-beam goes off (if I pull the dimmer switch - so as to flash my hi-beams, the left side Hi-beam comes on and the right side low-beam stays on). I have replaced the bulbs and changed the dimmer switch unit - no change. I have also taken the headlight switch assembly apart and cleaned it - for a moment both headlights appeared to be working ok then they reverted back to the previous problem plus now, the fog lights don't work either. As I write this, I am convincing myself the problem must be still in the headlight switch assembly and I will buy a replacement tonight, however, given the non-return policy on most electrical parts I am hesitant to spend the money if that is not the most probable cause. What do you think, could the problem be caused by faulty relays or other things. I would really appreciate your advise.

Answer
Hi Ian,
I just found your message in the pool, so don't know where things stand with the headlight problem. The system involves digital communication between three different modules so if you have satisfied yourself that the bulbs are all patent and the switch is good, then we are into an issue with those other parts of the system and their inter-communications (body control module, front control module, intergrated power module). I have an '02 main manual with the wiring diagrams but not the sub-manuals for the body communication system. One possibility is that some water may have leaked down from the windshield onto the body control module which will produce various 'gremlins'. So think back on the history to when you first noticed this.
Roland