w11 other cars

[jim 56]

Still having problems with my rear defroster on my 1972 W108 sedan.Following advice from here which I asked for a couple of weeks ago I cleaned fuse holders in the engine compartment.I found the fuse for the defroster.Fuse was bliown.Put a new fuse in and it immediately blew.So I figured it was a dead short.I cannot find it anywhere.I traced the wires as good as I could.Checked theswitch to see if it was grounding out it was not.The only thing I can think of is that there is a relay in the circut.Does anybody know if there is.And if there is a possible location.
Thanks Jim

[ja17]

Seems like the relay may be built into the switch itself on these cars. I would think the switch is suspect.

[jim 56]

I thought so also but I took the switch apart and checked everything. Nothing in the switch is shorting to ground but when I reinstall the switch it just blows the fuse. I actually thought that maybe it was overloading but I installed a 30 amp fuse and it still blew. Right now I have the switch bypassed and it works. That is why I think there has to be a relay because when the switch is in power must go thru the switch then somewhere else which shorts it out. I guess I just have to really have to trace the wiring all the way which could take forever since it is under the dash.