Go to Harbor Fright and buy the $19 infra red thermometer and take it to the junkyard with some crap zip cord, connect the window to a junk battery and use the IR tool to see if the wires heat up equally .

It's not rocket science .

Someone here should have the FSM and be able to post the proper resistance for meter testing .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Ok so I did some real world testing on my W211 this morning while it was in the garage.

I started it and ran it for a few minutes and then got out my trusty HF infrared thermometer.

Turns out it is possible if you hold the scanner directly against the glass, over the line, to see if it is heating up.

Get a baseline first before you energize it (take temperatures over the glass in a few places and mentally average them).

Then give it a few moments to get it to start warming up. You will probably have to work quickly especially if you have a drill battery to work with as it won't last long with the kind of draw the window has.

I was able to discern the glass getting warmer over each individual line. Granted this is a modern window with the painted lines but should be the same principle for the micro wires in the W126.

As proof I went to the top of the glass and shot the first 4 or 5 rows. These are part of the FM radio antenna and do not heat. These were as expected the same temperature as the glass before heating.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech