88 240 DL - Defroster Switch Suggests Electrical Problem?

Hi, I've got an 88 240DL sedan which is giving me a little trouble. The
rear defroster stopped working, and I noticed that the switch might have
failed so I picked up a new switch from a junkyard. I then noticed that the
fuse was blown, and I replaced both parts. But the new fuse, and two more
after that, also blew just after being inserted. The first new one blew
when I tried the switch, but the others blew without the switch being
pressed. Does that indicate a more complicated electrical problem? Please
let me know if you have any advice. Thanks,
Erik

PS: Thanks to Rojo2G for suggesting the Pick-your-part junkyard in Hayward,
I got some nice stuff there this morning.

 

You probably have a wire shorted somewhere, look at the back where they
connect to the window to start with.

 

Try pulling the relay out. It's white, and I think it's hanging around
just behind where the switch is mounted. (Don't confuse it with the
overdrive relay which is also white and just to the left of the
glovebox.) Also make sure that whatever else is on the fuse is not
causing the problem.

--
Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)