Don't you just love electrical "gremlins"
Can you imagine the $$ you'd have to drop at a dealer or shop to solve this...And believe me they are doing just about the same thing as you.
Do you have a multi meter?...if not get yourself over to a Sears/Walmart/Lowes/Homedepot...and get one. Shouldn't cost more than $30 bucks for a nice digital one. Best money you'll spend when chasing electrical problems.
Like I said before, just start eliminating the good, working parts from the unknown, bad and you'll narrow it down to those 2 or 3 areas...then concentrate on those.
good luck
