My father's 1981 300SD vaccum pump in the trunk bit the dust. It's getting proper power to the 3 pins(2 switched hot for up/down, 1 ground) but the motor's not going. I suspect a component on the circuit board. I doubt it, but wondering if anyone has a schematic for this circuit board? I'm going to try to replace as many of the components as I can, hopefully bringing her back to life. Thanks.

I don't have a schematic but when mine was doing that I opened it up and the circuit board was not making good connection with the motor itself. I have seen 2 different styles of motor configuration but on mine when I pulled out the circuit board there were two long pin connectors that weren't making good contact so I bent them just a little and it has been good for 3 years now.

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1983 300SD
200000miles

Thanks Phil. I actually soldered those tabs in place where they go into the receivers on the circuit board. A "just in case" move on my part which didn't fix it. I ripped open the part of the unit where the wires go to and screwed myself over in the process because I can't get the parts back together correctly. I called my MB mechanic and he's got a used one for a couple of bucks so I'll just go that option now.