Flashing & inoperative rear defroster switch
 

RE: my 1995 E320. Yes I know what the owner's manual says about conserving power and redirecting it to other electrical consumers... but my situation doesn't make sense. My alternator is a remanufactured MB/Bosch one that was just done last year (actually removed, rebuilt, and reinstalled a few days later), the voltage regulator was also replaced. The battery is two-years old and gets recharged/equalized about once a month just for the hell of it. This just started happening a few weeks ago for the first time. The defroster switch flashes within 10 seconds of being activated. I've even tried turning everything off for a minute and increasing the RPMs and then turning it back on to see what happens. It still flashes and won't clear the back window. What gives?

Can you feel the window getting warm after a few minutes?
Have you checked the FUSE?

Actually, I tried this many times with the window fogged up on the inside (and the outside after a snowstorm). The fuse is intact too. Is there a relay for this?

Yes, part of the combination relay. MB number 201 821 02 47

Hmmmm, not good. I proactively replaced that last year when my friend's 1994 E320 suddenly wouldn't start (I think) and we traced it back to that relay. I changed mine to avoid that same fate. I recognized that part number and I still have the MB box that relay came in, that's definitely the one I replaced. What next?

This may or may not help...but could it be the switch/module itself?

I have a Crossfire which of course is quite different (though still MB bits) and generally the consensus is that when a switch behaves in such a fashion it is either the switch/switch module or the (heater) element itself...

If you still have the old relay module, try swapping it back to see if it works.

Otherwise, try a used one, I believe that the same module was widely used throughout the 124/126/201 models.

I'll try swapping it back to the old one to see what happens. Thanks.