This output power line is drived by Carberry, following (with some timing rules) the status of the ignition of the car.
The ignition input can be either detected from CAN Bus, than from ingnition input wire (pin 3 of main connector).
Ignition output wire can be used to power a LCD monitor, or any device that has to be switched on and off accordingly the status of the car ignition.
Note that you can draw a maximum of 2.5A from this line.