During the applied-pressure leak test, what maximum air loss in one minute is allowed for a combination vehicle with the engine off and brakes applied?

• A.10 psi in one minute
• B.1 psi in one minute
• C.There is no limit as long as the low-air warning stays off
• D.4 psi in one minute

Why

The standard allowance is 3 psi per minute for a single vehicle and 4 psi for a combination vehicle on the applied test, because more units and connections are involved. Losing more than that means finding and fixing the leak before driving.

Manual topic: Combination Vehicles - Air Brake Tests · From the Combination Vehicles practice bank (CV-201).

Practice this subject as a full test

More Trailer ABS & Brake Checks questions

• What should the trailer ABS malfunction lamp do when you first power up / start the vehicle, if the system is healthy?
• The yellow ABS lamp for the trailer stays on after you are moving. What does it mean and what still works?
• Where is the ABS malfunction lamp for the trailer itself commonly mounted (in addition to any dash lamp)?
• What is the main safety benefit of trailer ABS for a combination vehicle?
• You couple to an older trailer that was built before ABS was required on trailers. How should that change your driving?