I disconnected the park brake button and after plugging back in got a Park Brake fault.
It was working perfectly before and all I did was unplug then plug back in. I've cleared the faults with SDD.
I've ran Park Brake calibration on SDD and that succeeds, you can hear the brake activating.
As it stands, if I start the car no fault shows. The Park Brake fault only shows if I hold the button down for a few seconds. The brake is not working automatically.