I have a new P2 controller and the manual says hold the manual brake lever over and set to 6 to start with... Do you do the initial setup and testing
With an empty trailer or does it matter?
for an empty trailer i set to zero then did some on pavement testing increasing the gain untill i got to a point were i got some trailer brakeing without locking up the wheels.
The book way of doing it is adjust to a point where you can lock up the wheels at 10 mph then back them off to the point where they just will not lock up.
You must adjust each and evey time as load varies.