Im working on a 1992 w250/diesel for a friend. The problem is that the windshield wipers and washer pump intermittnently run on there own with key on. A known good switch has been tried and wiper module replaced. The other problem is the radio quits working , but it is the inst. cluster fuse that is always blowed instead of the radio fuse, and when it blows the instruments and lights still work. This truck is bone stock and has not been messed with. The owner told me that the radio was working when the wipers acted up, but when I got it, the radio was not working and I never have witnessed the wipers acting up. Is there a commonality between circuits or . Please help. I have not dug deep, wanting to try this resourse to speed process