What should you do if your brakes fail while driving?

When brakes fail while driving, the most effective response is to pull the parking brake gradually. This action can help slow down the vehicle without causing a sudden stop that might lead to loss of control. The parking brake is designed to engage the rear wheels, providing a secondary means of reducing speed and potentially bringing the vehicle to a safer stop.

Engaging the parking brake gradually allows for more control and reduces the risk of skidding, which could occur if the brake is applied too suddenly. It's important to do this while maintaining attention to the road and steering the vehicle away from potential hazards.

The other options are less effective for managing brake failure. Shifting to a higher gear can momentarily slow the vehicle down, but it won't provide a reliable means to stop. Steering towards a ditch could be dangerous and may lead to an accident rather than a controlled stop. Using the horn to alert others is not a practical solution for stopping the vehicle and does not address the immediate danger posed by brake failure.