RE: a 2000 ML 430, I'm not too well versed in the M-class so I'm hoping someone can help me. It's my friend's car and I'm trying to help him out, I replaced the entire window switch-pack back in August 2013 because the driver's window stopped moving. I replaced the driver's window regulator in April of this year because the window was straining to move and barely moved. All was well until last week. The driver's window only goes down (as normal) but will not go up. I figured it has to be the window motor this time since it's original. I tested for voltage at the window motor socket. I get 12 volts when the driver's window switch is depressed, and 12 volts when the driver's switch is lifted. So the switch is doing its job by sending out 12 volts to the motor. I replaced the motor today with a MB-brand motor. Still doesn't work. The window only goes down but not up, just like the old motor. I found a motor from an old 124 I have and attached that to the socket - same thing, that motor's wheel only rotates in one-direction. What am I missing? Is it still the switch, is that possible even though I'm getting 12 volts?

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