windshield wiper problems

[dieselfuelonly]

i have and 86 diesel and it has ran good for me for a long time but recently the wipers quit working. i checked the fuses and they are all good, someone told me there is a box under the steering colum that controls the wipers and that might be bad has anyone heard of that

[DiGtownIN]

I was hoping someone could help answer this also. We have a 03 F350 7.3 and one day the wipers would only work in the full rain and hurricane speed, intermittent would go once, but not repeat. Now they are not working at all. Have checked fuses and everything looks good.

Any suggestions would be greatly appreciated.