Info on hand valve brake on 97 Pete

I've got air going through my hand valve and out the foot valve exhaust when i use the hand valve and out the hand valve exhaust when i use the foot pedal. Does this with both buttons in or out Is there a check valve somewhere in the system that i cant find that is bad? Plugged off the supply and feed lines on the hand valve and all goes back to normal, while its acting up i have very very little service air to the blue line with the trailer brakes released Just replaced the foot valve and no different thinking its either the hand valve itself or a check valve if there is one.

 

Yep it was the tractor protection valve. Thanks