Just had the same problem.
It was indeed the set of switches on the dash.
After we bought a new switch assembly, for about $50, I took the defective one
apart to see if I could see the problem.
It was obvious, the solder joints around the pins that plug into the wiring
harness were cracked. I resoldered them and everything works fine.
It's very easy to get at the switch and it snaps apart easily too. Try this
before you spend the cash for a new one, I wish I would have!!!