Constant air two trailer service brakes

The problem I’m having is there is constant air going through the trailer service line whenever you push in the trailer supply valve. Also the brake light is always stuck on as soon as you build a little bit of air in the system. I’ve replaced the tractor protection valve, and the foot-break valve, but neither of those solved it.
The last thing I can think of would be the parking brake valves in the cab… would there be anything else anyone knows about that could cause this?

 

It’s coming from the truck, any ideas on what valves what caused it other than the pedal brake valve and the tractor protection valve which I have replaced?