Michigan CDL - Air Brakes Practice Exam

Brake lights serve a critical function in air brake systems by signaling to other drivers that the vehicle is slowing down or coming to a stop. This communication is vital for maintaining safety on the road, as it helps prevent rear-end collisions and allows other road users to react appropriately to the changes in vehicle speed. When a driver applies the brakes and the air brake system engages, the brake lights illuminate, providing a visual cue that enhances the predictability of the driver’s actions.

The other choices do not accurately describe the role of brake lights. For instance, indicating low air pressure is a function of a separate warning system, not the brake lights themselves. Similarly, while air filter maintenance is relevant to vehicle operation, it does not involve brake lights. Finally, the activation of the spring brake feature is a mechanism related to the air brake system's design and functionality rather than a role of the brake lights.