Complicated Electronic Problem

[bamkay]

I have a 1989 Eddie Bauer Edition that has developed a complicated electronic problem that I am trying to fix.

Here's the problem: Turn the van on, everything is okay. After a few seconds, the windshield wipers come on (switch is off). Turn on the heater, and the wipers go off. Leave the heater on, and turn on the running lights, everything is okay. Turn on the headlights and the wipers come back on (switch is still off), and the right (passenger) headlight is dim.

I have checked the fuses, everything okay...

I have checked the control switches, everything okay...

I have checked for shorted wiring, everything seems okay...

Anyone out there that can help??

Dont want to go the mechanic route till I have exhausted this route. The tips and help from this forum have helped quite a bit with the van so far.