This bFlash feature allows the ABS/ESP to be deactivated in a given vehicle, preventing any intervention on the dyno. If your dyno does not support 4WD, you must unplug the transmission (Haldex...) as usual to switch to 2WD mode. On most vehicles the dyno mode switches to 2WD, but we do not recommend this procedure because it's not the main feature but a consequence !
Keep in mind to deactivate dyno mode before reading / writing any control unit in the vehicle. Caution! Never drive the vehicle on the road with dyno mode enabled for your safety and that of others.