If you vehicle has a dual air brake system and a low air pressure warning comes on for only one system, what should you do?

• A. Continue driving to the nearest safe stop
• B. Stop. Safely park and only continue after the vehicle has been fixed
• C. Check the air gauge and drive slowly
• D. Ignore the warning if the other system is fine

Answer: (B)

In a dual air brake system, there are two independent air circuits that control braking. If the low-air warning comes on for one circuit, that circuit doesn’t meet the safe pressure required for reliable braking. Relying on the other circuit isn’t enough, because a failure in the first circuit could lead to reduced or total braking capability at any moment. So the safest action is to stop as soon as you can safely, park, and only continue after the issue is repaired and pressures are restored to the proper levels.

Continuing to drive toward a stop or driving slowly while ignoring the warning risks a sudden loss of braking on that circuit. Ignoring the warning altogether is unsafe because a single system with insufficient pressure can compromise stopping power, especially in emergencies.