Your trailer has electric actuated brakes (12V DC Voltage to magnet that causes brake shoes to engage drum)
Some trailers have disc brakes that are hydraulically actuated and use 12V DC Voltage to engage them
The P2 Controller can be set up for either system.
It is just a circuit board that controls 12V DC Voltage being sent to trailer brake system.
As with anything it can wear out/break.....short circuit/fault.
New vs used.....have seen brand new electronic not work right out of box but it was warrantied
Personally know the individual selling one------buy on condition that it works
