Answer :
Final answer:
To test the tractor protection valve, after charging the air brake system and turning off the engine, you should disconnect the air lines to ensure the valve is working properly.
Explanation:
To test the tractor protection valve, after charging the trailer air brake system and turning off the engine, the correct step to take is to disconnect the air lines. At this point, the tractor protection valve should activate and keep the air from escaping the tractor, which prevents the air pressure in the brake system from dropping quickly. This is a safety feature to ensure that there is sufficient air pressure for the tractor brakes, even if the trailer becomes disconnected.
