w108 280 SE sedan 1972

[jim 56]

I wonder if  I can get some help. My rear window  has the defroster in the glass the electric. I'm looking for the color of the wires  that go to it and what fuse it's on. Can't seem to find it on any of the diagrams. This the switch on the dash came on but about a minute later it went out without defrosting the window.

[ja17]

Most likely it is a corroded fuse end. There should be several small auxiliary fuse boxes under the hood. They have small dark brown plastic covers. These small fuse boxes are usually added for accessories like rear window defrosters. Check all the fuses in the auxiliary fuse boxes and the main fuse box under the dash. You can twist or clean each fuse to make sure it make contact. Since the ends tarnish and corrode the fuse may show good but not actually contacting. Twisting them can renew the connection. Spray a bit of electrical contact cleaner on the connection to prevent the problem in the future. 

[wwheeler]

Joe brings up a good point and that is as routine maintenance, twist the fuses once a year to prevent issues. I use a dielectric grease on the fuse ends to prevent corrosion from settling in. I don't there is an issue using that but wondering what others say?

[jim 56]

Thanks for the replies. If I recall last year my lights were out on one side and the problem was the fuse end was corred.I will check them all for defroster problem.