Normal current draw W201 power window motors - PeachParts Mercedes-Benz Forum

d.delano · #1 06-28-2012, 10:15 PM

Hello all
Anyone here know how what the normal current draw should be from the power window motors? I'm blowing fuses and need to get it sorted. Thanks

tecqboy · #2 06-28-2012, 11:26 PM

I believe that if the motor is operating within spec., even when it is stalled, it won't draw enough current to blow the fuse; generally 10 or 15 amps. So, is it one window that blows the fuse or any window? If it is only one window, it's probably a bad motor in that window regulator. If it is any window, that blows the fuse then it may be wiring or a bad switch. Connectors in doors sometimes get wet and corrode. Some cars, like the 129 SL's have memory windows and then it really gets complicated. But if the motor is running freely ( out of vehicle ), I've measured them in my R129 at 2 to 3 amps. My windows were binding due to dried up and hardened grease. Re-lubricating solved my blowing fuse issue.

d.delano · #3 06-28-2012, 11:56 PM

It blows #8 fuse whenever anybody rolls the windows down using the console switches. Both switches are newish and have been functioning fine. Fuse #8 links the front passenger/rear driver's windows. I suspect either broken wires, a sticky regulator track, or a stiff motor in one of those doors as the cause. Car has been sitting for long periods so the sticky reg or motor would be likely in my mind.

So before I go pulling the door panels off to check I wanted to know how many amps they were supposed to pull. I suppose since they are 8 amp fuses the motors should not be pulling more than 8 amps, and when I find the one that is pulling more than 8 amps I will theoretically have found my problem. I hoped somebody here who had gone through similar would be able to give me a definitive number.

tecqboy · #4 06-29-2012, 12:56 AM

Well, I don't know for sure, but I suspect these window motors are shunt wound type. They are designed to turn at a constant speed regardless of the load. So, even as it gets harder for the motor to move the regulator, it doesn't slow down, it just draws more current. When I had mine on the bench and out of the car, it drew between 2 and 3 amps from a regulated power supply. run / start. But that doesn't mean yours should be the same.

lsmalley · #5 06-29-2012, 01:21 AM

If I were you, I would try pulling those window switches and swapping them with the 2 that ate on the opposite windows, and don't reconnect them until you rule out that they aren't the problem. This same thing happened to me last month and I went through 5 fuses until I changed out the front passenger switch. Usually its the switch that you notice that you use that causes the blown fuse. So if you roll down the rear driver window and nothing happens then its most likely the front passenger window switch. So take off the front passenger and rear driver switches from the console and try using just the rear driver switch on the front passenger socket. If the fuse doesn't blow, then its your front passenger switch that is the problem. If you try it with both switches and they both blow the fuse try using the window switch from the front driver socket, if that doesn't blow the fuse, replace the other 2 switches as they are bad. Report back and let us know what happens.

d.delano · #6 06-29-2012, 01:33 AM

Quote:

Originally Posted by lsmalley

If I were you, I would try pulling those window switches and swapping them with the 2 that ate on the opposite windows, and don't reconnect them until you rule out that they aren't the problem. This same thing happened to me last month and I went through 5 fuses until I changed out the front passenger switch. Usually its the switch that you notice that you use that causes the blown fuse. So if you roll down the rear driver window and nothing happens then its most likely the front passenger window switch. So take off the front passenger and rear driver switches from the console and try using just the rear driver switch on the front passenger socket. If the fuse doesn't blow, then its your front passenger switch that is the problem. If you try it with both switches and they both blow the fuse try using the window switch from the front driver socket, if that doesn't blow the fuse, replace the other 2 switches as they are bad. Report back and let us know what happens.

Yeah I'll swap the switches first, but I'm not going to hold my breath that it's going to be that easy. One of them is brand new anyhow. I've been kinda noticing a little sluggishness from the front pass window recently as well. I'll check the easy points first though.