Could be bad switch or wiring....depending on the condition of the control box and age of it. I have taken apart some before that were working...but the wiring would scare you!! If you have ever taken one apart you know the wiring and such on the inside of it makes some of the sharpest bends and turns i've ever seen for wire. I have seen quite a few fray.
Like IBNFSHN said....if its the switch...which it probably is....get a different switch...not the dealer replacement. You have alot of options. I would get one on the steering wheel, like the one from bass pro....
Teleflex Pro-Trim
These are MUCH safer..this isn't the one I was looking for...there is one that mounts to the steering wheel itself...and just has two buttons on it. Works just as well...and is cheaper. Before I paid for dealer parts to fix the control box I would just disconnect the wires for that switch and add something that would be better and safer. Just my opinion.
"But if serving the Lord seems undesirable to you, then choose for yourselves this day whom you will serve, whether the gods your ancestors served beyond the Euphrates, or the gods of the Amorites, in whose land you are living. But as for me and my household, we will serve the Lord.” Joshua 25:15