What should happen before the air pressure in an air brake system tank falls below 55 psi?

Question

The low air pressure warning signal must activate before the air supply pressure drops below 55 psi in the air tank. If the warning signal does not turn on when being tested during an inspection, the vehicle is not safe to drive.

Accepted Answer

The warning light should activate.

Answer

The vehicle will be unable to shift out of gear.

Answer

The front lights should flash.