How do you have to disconnect the air lines when detaching a trailer?

When detaching a trailer, you must disconnect the air lines properly to ensure safety and avoid damage. The correct procedure is to first disconnect the emergency line (red hose coupler), which controls the trailer's emergency brakes. If the hoses are combined into one unit, you should disconnect both lines simultaneously. Disconnecting the service line (yellow hose coupler) first is incorrect because it handles the normal braking function and should only be disconnected after the emergency line to prevent unintended brake activation or air loss. Following this order helps maintain control and prevents accidents.