Georgia Commercial Driver License Practice Test

What is indicated by a red light in the air brake system?

1. Normal operating pressure

2. Low air pressure warning

3. Brake failure

4. Excessive pressure

The correct answer is: Low air pressure warning

A red light in the air brake system serves as a critical warning indicator for drivers operating commercial vehicles. Its activation signifies a low air pressure condition in the brake system, alerting the driver that the air pressure has fallen below a safe operational level. This warning is essential because air brake systems rely on sufficient pressure to function effectively; inadequate pressure can impair braking performance and could lead to dangerous situations. Therefore, the red light prompts the driver to address the situation promptly, ensuring safety on the road. In the context of the other response options, normal operating pressure would not be indicated by a red light; instead, a green light or no light might be present. While brake failure is a serious concern, it typically involves additional warnings or indicators beyond just a red light. Lastly, excessive pressure would not trigger a red light, as that would indicate a different kind of malfunction.