I had the SAME EXACT PROBLEM on my 2002 F350.. Turns out, my passenger side dome light bulb burnt out, causing the fuse to blow in the underdash fuse box. It took me awhile to find the problem, but when I replaced the fuse, it blew again. After finally removing the blown bulb, all was perfect.. I still havent replaced that stupid bulb.. Hope this helps you, I was frustrated for a bit..