Spring brakes come on:

Question

Spring brakes come on automatically when air pressure drops to an unsafe psi level. Instead of waiting for the spring brakes to automatically activate, you should safely exit the road as soon as you notice the low pressure warning signal and bring your vehicle to a stop while you are still able to control the brakes.

Accepted Answer

When too much air pressure is lost.

Answer

When a control on the dashboard is activated.

Answer

When the tires have minimal tread depth.

Answer

When the brakes are noisy.