What is a sign that a vehicle should be rejected regarding air pressure warnings?

A vehicle should be rejected for inspection if the warning device is not functioning. This indicates that the driver will not be alerted to low air pressure conditions, which are critical for safe operation, particularly in vehicles equipped with air brakes. A non-functioning warning device can lead to situations where the driver is unaware of potentially dangerous pressure levels that could compromise braking efficiency.

The function of the warning device is crucial in ensuring the driver is aware of the air pressure within the system. If the warning mechanism fails, it creates a significant risk, as the vehicle may not be able to stop effectively, leading to hazardous driving conditions. Proper function of safety systems like the air pressure warning is essential for overall vehicle safety.

Looking at the other circumstances: if a warning device turns on at an appropriate threshold (for example, at 15 p.s.i.), it is still providing a necessary warning; similarly, if it activates after a pressure drop or sounds intermittently but still functions, it indicates that while the system may have issues, it is still operational enough to give necessary feedback to the driver.