I am not sure the avionics bus is wired the correct way? When I installed my GTN750 I selected the avionics bus to power it. The GTN then comes on instantly, even if the switch is off on the dash. Further  to my confusion if you turn off the Avionics switch and the main Battery bus the GTN stays on! Definitely not the right behavior as this would indicate the avionics bus is always powered???...or should I be selecting a different bus to power the GTN? Just looked at the GTN ini.  file to a