So I got the rear window to work, turned out to be a cold solder joint on the RR up regulator within the CCM even in the replacement CCM.

I looked over the original CCM and stopped counting after about 20 cold solder joints. Went through and proceeded to repair those but upon testing the unit again, my control relay (in the fuse box) was still clicking albeit not as badly as before. Pulled the CCM and will have a look for more bad solder joints.

Like several other relays and components from this period, MB must have been using bad solder or just a product of age, but bad solder joints seem to be a problem with many components. Rather than replace, have a look to see if you can spot them under magnification and repair rather than replace as even your replacement part will develop this issue.

Will post a final update if I can get my original CCM to work again as a spare since my replacement one is up to task now.

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)