Hi ive been on with the car all day and no further forward and was hooing some one can shine a bit light on the matter i have a 2001 ml 270 cdi the front drivers window goes down no problem at all but wont come back up now i have ruled the motor out as i have a spare which i tested on passenger side and worked both ways up and down but only down on drivers side so then i looked at the switches on the console checked them all seem to be operating as should so then i broke the old test light out and when operating the switch get a live feed at the plug of the motor when operated up and down so the car is providing power to motor i also dismantled the plug and swapped the wires round and operated the switch in the downward position and it put the window back up so put it back to the way it supposed to be and it still wont operate up only down has anyone had this problem before i have changed fuses 29 and 30 too just dont knowwhere to go from here i cant see it being the switch if i operate it up and getting a live feed at the motor or am i wrong thinking this i dont know im pulling my hair out with it
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Ted
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Sounds like it has to be the switch if you swapped the wires and it went up. I'll explain better later.
Ted
MB Enthusiast
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- Feb 26, 2004
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- Lexus RC300h F-Sport, Yamaha XVS 1100, Toyota C-HR GR sport
OK, first of all the disclaimer - I don't know how the windows work on the early ML and I don't have a schematic, but...
Window motors usually work with two wires where the supply is either applied in one direction for up, and the other direction for down - that is there will be a feed on one wire for up, while the other is earthed, and vice versa for the other direction. This is achieved via switch contacts, relay, or door controller.
The other was is to have three wires with two windings inside. There is a permanent/ignition live to the centre winding, while the switch (or controller) earths the appropriate winding. Simpler, but not often used as they are less powerful and the motor is more expensive.
So, on yours, you have proved the motor, both by substitution and by rewiring the switch.
You also seem to have proved the wiring and any relays/controllers as by rewiring the switch and the window goes up.
Once you have eliminated the impossible, whatever remains, no matter how improbable...
Window motors usually work with two wires where the supply is either applied in one direction for up, and the other direction for down - that is there will be a feed on one wire for up, while the other is earthed, and vice versa for the other direction. This is achieved via switch contacts, relay, or door controller.
The other was is to have three wires with two windings inside. There is a permanent/ignition live to the centre winding, while the switch (or controller) earths the appropriate winding. Simpler, but not often used as they are less powerful and the motor is more expensive.
So, on yours, you have proved the motor, both by substitution and by rewiring the switch.
You also seem to have proved the wiring and any relays/controllers as by rewiring the switch and the window goes up.
Once you have eliminated the impossible, whatever remains, no matter how improbable...
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