During the static (brakes released) leak check with the engine off, what is the maximum allowed air loss rate for a combination vehicle?

• A.3 psi in one minute
• B.8 psi in one minute
• C.No loss at all is allowed, even a fraction of a psi
• D.15 psi in one minute

Why

With the brakes released and the system fully charged, a combination vehicle may lose no more than 3 psi in a minute. More than that points to a leak in lines, fittings, or chambers that will only grow underway.

Manual topic: Combination Vehicles - Air Brake Tests · From the Combination Vehicles practice bank (CV-202).

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?