CDL General Knowledge TestDriving SafelyEasy
A commercial driver is conducting a pre-trip inspection of their air brake system. They notice that the air pressure gauge shows a steady reading of 80 psi, and the low air pressure warning light and buzzer are activated. What is the most immediate action the driver should take?
- ADo not drive the vehicle and have the air brake system inspected and repaired.
- BPump the brake pedal several times to try and build up air pressure.
- CDrive the vehicle to a nearby service station for inspection.
- DContinue the inspection, as the system will build pressure once the engine is started.
Show answer & explanationAnswer & explanation
Correct answer: A. Do not drive the vehicle and have the air brake system inspected and repaired.
If the low air pressure warning light and buzzer are active at 80 psi, it indicates a critical issue with the air brake system pressure, which is below the safe operating range. Driving the vehicle in this condition is extremely dangerous and illegal.
Why the other options are wrong
- B. Pumping the brake pedal would further deplete any remaining air pressure, making the situation worse.
- C. Driving an unsafe vehicle, especially with critical brake system warnings, is highly dangerous and prohibited.
- D. The warning indicates a problem that won't resolve by merely starting the engine; it's a safety hazard.
Low Air Pressure Warning
A safety feature in air brake systems that alerts the driver when air pressure drops below a safe operating level (typically 55-60 psi), indicating a need for immediate attention.
- Activates both a light and a buzzer.
- Indicates insufficient air pressure for safe braking.
- Requires immediate vehicle inspection and repair.
Memory trick: Low pressure, no go, check it slow!