Remember that the door switch and the console switch must both be good for the rear windows to work. Additionally, the contacts in the switches corrode with time and use. If they are worn/damaged/dirty, there might be enough contact to give you a reading on your voltmeter but not good enough to pass the several amps of current that the motor needs. Fortunately, the switches can be taken apart and cleaned.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970