Hey all, having trouble with driver window in my 2008 astra coupe. Took the motor out and it benched tested fine, replaced the switch which is getting power, window will still not go down. Passenger window works as it should. when the door is open and i press the down button the door ajar light in dash blinks. The plug that goes into motor is getting 12 volts + when i check it with volt meter, constant, up, and down. Does any one know thee small black wire going to the window motor? also i know the window regulator is good, I put 12v to the motor and got it to go down, just not with the switch.

Thanks,
Ken

 

Ken
I do not as I type have an answer for you but yet another question. But it is related.
I have had to replace the motors in both doors of my 1994 S2 Saturn coupe. The wiring diagram is out in the manual that is in the trunk of the car. So----
What causes the motor to stop driving?
When in Auto mode, that is the switch is pushed and the window starts down with no further input from the switch. A switch that acts as a momentary switch that is power is applied when the switch is pushed and the power goes away when the switch is released the window continues down until it comes to a stop.
Why did it come to a stop?
When the window can go no further the power to the motor some how stops being applied.
Now reading this it sounds just a bit stupid, but I don't know the answer.
It is as if some circuit senses an increase in current caused by the window being unable to go any further and the motor is now stalled, not turning and in this mode, electric motors do indeed draw more current. (Basic electric motor theory) so what is it that causes the power to be removed from the window so the motor does not burn out ?
How does this relate to your problem? My 94 Saturn SC2 sits outside and has all of it's life and the window track or runners have gotten dirty as have the windows themselves. So the same thing happens, you push the switch and it does not move as if the power was not applied.
Yet bench testing shows no problem.
However very carefully cleaning the window then using a generic furniture paste wax, the window was waxed. The procedure removed the film of crud off of the glass and in addition wax added to the glass. Solved the problem. The window would not work before in the direction the auto movement functioned. And now it works fine.
So what ever sensed the non-movement of the window, that is the motor stalled thus drawing maximum current or something like that no longer was a problem because the window worked smoothly.
The answer to the question may relate to a solution to the problem. If I knew how it was supposed to work in the first place
And?
I don't.

 

As a follow up to Unc's post (after which I will get to your question):

On older cars,, I believe when NOT using the auto down feature, the motor just stalls out at the top or bottom of its travel. If you try to make it move past its limits, it does indeed try to spin the motor, but it can't move, so it does indeed pull alot of current. usually you can see the lights dim when you work the switch with thee window at its limit of travel, indicating current is still going to the motor.

There is probably a thermal overload breaker in the motor which pops the circuit open to protect the motor from the people that are stupid enough to hold the switch for 2 minutes straight after the window reaches its limit of travel or if your 3 year old is playing with the switch for 15 minute straight and overheats the motor.

As for auto down, I'm guessing that is a timed circuit that will drain a capacitor at a known rate sufficient to get the window all the way down and then some (to account for the motor aging and slowing down). Once the capacitor is drained past a certain limit, a low current limit sensor probably kicks in and pops the circuit open.

-----
Since there is an issue with bogus door ajar blinking, I am going to GUESS that the issue is either a crossed circuit such that the current intended for the window motor is taking a different path through the door ajar light circuit and there is indeed 12 at the motor but there is not enough CURRENT available to drive the motor, as some of it has been diverted.

I would measure the CURRENT in the motor circuits near the motor for driver and passenger side and compare. Most multimeters have a 2 amp fuse for current measurement so you may have to use a dedicated ammeter to make the measurement.

OR

It is some issue with the Body Control Module which sits between the window switch and the window motor, and the BCM is not sending current to the motor even though the voltage for the switches is there to operate them.