A tractor protection valve includes a trailer service brake portion, a trailer parking brake portion, and a stability control portion that are each formed within a common valve body. In one example, the trailer service brake portion includes three inlets that can be used to apply a trailer service brake. The three inlets cooperate with a service brake blocking piston, a service brake relay piston, and double check valves to apply the trailer service brakes as needed. The stability control portion includes a solenoid that can direct air to apply the trailer service brakes in response to a stability control signal. The trailer parking brake portion also includes multiple ports that cooperate with a parking brake piston and valve to control application and release of the trailer parking brakes.