The driver must be able to see a warning that is given before air pressure in the service air tanks falls below:

The driver must be able to see a warning that is given before air pressure in the service air tanks falls below:

• A. 40 psi
• B. 50 psi
• C. 60 psi
• D. 70 psi

Answer: (C)

Low air warning is there to give you a heads-up before the service air pressure gets low enough to affect braking. This warning is set to come on at about sixty psi, so you have time to slow down and stop safely while the system still has enough air to function. If the warning appeared at a lower pressure, you could be closer to losing braking power before you notice it. If it appeared at a higher pressure, you’d get alerts too early, which can be annoying and distracting. The sixty psi threshold provides a practical balance: enough warning time to react, but not so early that it’s meaningless during normal fluctuations.