What is the purpose of the low air pressure warning in an air brake system?

• A. To warn of high pressure
• B. To warn of low pressure
• C. To indicate a clogged filter
• D. To indicate engine overheating

Answer: (B)

The purpose of the low air pressure warning is to alert you that the air pressure in the braking system is dropping toward a level where brakes may not work reliably. As pressure falls, braking power can decrease, and at very low levels the vehicle’s safety features (like the parking/emergency brakes) may engage to prevent a total loss of braking control. The warning gives you time to stop in a safe place, check the system for leaks or faults, and let the compressor replenish the air. This signal is specifically about low pressure, not high pressure, a clogged filter, or engine overheating.