I replaced my drivers window regulator with one that I picked up at a pick-n-pull. I tested it by directly hooking it up to my battery. It tested fine. I put it in the car and it worked great for about 5 minutes. Now it is dead as well.

Not sure what would cause this.
Is there something I should be looking at that kills regulators?

If bypassing the Switch by using jumper Wires directly on the Motor leads allows everthing to work OK the regulator is not an issue.

I have not read of one thread where someone has replaced the Power Window Relay but there is one.

Also what do the Fuses look like now?

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84 300D, 82 Volvo 244Gl Diesel

If I put a multimeter on the wires that run to the regulator I can see it giving 9-12V. I am sure that power is getting to the motor.

Is the Motor Trying to turn?

The Window Motors are not grounded to the Chassis as part of their Curcuit like the Starter Motor is.
The Motor direction is changed by changing the Polarity of the Electrical Current going though the Wires.

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84 300D, 82 Volvo 244Gl Diesel

Could be a broken wire in the accordion joint between frame and door.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

It was a bad regulator.......

I do not usually think that will be it, but I put another one in last night and it worked fine.

It's been a while since I looked at a 124, but I think you should have a two pole terminal block under the door panel, to which the regulator motor hooks up.

1. Use a multimeter to test the voltage between each of these poles and ground. BOTH poles should be at 12v relative to the chassis ground. If this is not the case, then the problem is somewhere between the switch and the door. (or a bad relay or fuse)

2. If you have power, then move to the next test. When you flip the switch in either direction, one pole should be grounded, while the other remains at 12V. So have someone hold the switch, say in the down position, and test voltage again. If one pole doesn't go to zero, the problem is the switch.

3. If you've reached this point, then someone is holding the window switch down, you have 12V on one post and no voltage on the other. Switch your meter to measure ohms and measure between the no-voltage post and any good ground. Resistance should be a few ohms at most. If this is the case, then the new motor is bad. If resistance is very high or infinite, the problem is either the switch or the ground at the switch.

So the voltages at the two poles was exactly as it should have been.
I tested it with a friend who held the button and I could watch it switch polarity and the voltages were all within correct tolerances.
I probably should have been a bit more explicit.
I was worried that there may be something that would short out the regulator.

It turns out that the regulator that I had picked up at the Pick-N-Pull was most likely on it's last leg when I put it in. It is rare that it would have tested OK at Pick-N-Pull and then die at home but not impossible.

When I put the new on in last night it worked great.

When you say "regulator" do you mean "window motor"?

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"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

Yea the motor that allows the window to go up and down.

Amazon.com: Mercedes w124 Window Regulator Front Right GENUINE w/O motor: Automotive

Funny that one on Amazon did not have the motor, but yea that whole mechanism is what I replaced.

With the motor.