Midgate Latch Operation
WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
When the midgate window is in the full down position and the midgate latch release switch is activated, ground is supplied to the midgate control module. The midgate control module will then provide 12 volts to the midgate latches and release the midgate.