DEI already makes a product for this. when I had my alarm installed I had the modules installed with the alarm. also when the alarm arms it automatically closes the windows. or I can remote open the windows as well. and the modules are current sensing so if the load is to great the windows stop.
Exactly right, I forgot about this, thanks for reminding me! There is also some other company that makes a little widget that you plug into the OBD port that makes it so when you press the lock/unlock buttons on the factory remote in a certain sequence, it will close/open the windows.
It would be very easy if you knew the message structure and databus intricacies of the Class 2 databus (just make a little gadget that taps into the databus and sends a "window up" message to the driver/passenger door modules)....but I dont, and its all proprietary info that GM keeps to themselves.
The way I was thinking of doing it (I was completely forgetting that a data message could raise/lower the windows) was actually just making a little piggy-back device that would trigger the window motor individually, etc... A really Rube Goldberg method to say the least.