JJ Keller Entry Level Driver Training CDL Practice Test 2025 – Comprehensive All-in-One Guide to Exam Success!

The correct answer is based on the function of the low pressure warning alarm or light within the air brake system. In commercial vehicles equipped with air brakes, maintaining adequate air pressure is vital for the proper functionality of the braking system. The low pressure warning device is specifically designed to alert the driver when the air pressure falls below a certain threshold, indicating that the brakes may not function effectively.

When the air pressure is insufficient, the warning device activates to notify the driver of the potential danger. This early warning allows the driver to take necessary actions, such as bringing the vehicle to a safe stop and addressing the issue before it results in brake failure. Understanding this is crucial for ensuring both safety and compliance with regulations regarding air brake systems.

The other options, such as a low battery alarm, high temperature warning light, and engine overheating indicator, serve different purposes related to the vehicle's electrical system and engine performance, but they do not pertain to monitoring the air brake system's pressure.