Question When operating a vehicle with a dual brake system, a driver should: Answers Let the vehicle warm up before driving to ensure that fuel reaches the engine. Wait to begin driving until the air compressor builds up a minimum pressure of 100 psi in both the primary and secondary systems. Begin driving just after the vehicle starts. Pump the pedal about 20 times to build pressure, then begin driving. Explanation Before driving a vehicle with a dual air system, allow time for the air compressor to build up a minimum pressure of 100 psi in both the primary and secondary systems. Take a FREE Practice Test Now This questions appears in the following tests: Texas Knowledge Test Class A , Alabama Air Brakes , Georgia Air Brakes ,