During a trip, which shut-off valves should be open?

Question

When starting a trip, be sure that all shut-off valves are in the open position, except for the last valves on the rear trailer. It is important that air reaches the brakes on all trailers and that the air is not able to escape from the back of the vehicle.

Accepted Answer

All shut-off valves should be in the open position, except the rear shut-off valves.

Answer

All shut-off valves should be open.

Answer

The rear shut-off valves should be open.

Answer

No shut-off valves should be open.