Which brake system should be tested while the vehicle is stopped?

The parking brake should be tested while the vehicle is stopped to ensure that it is functioning properly. It is designed to hold the vehicle stationary while parked, preventing it from rolling away. Testing the parking brake in a stationary position allows the driver to confirm that it can maintain the vehicle's position and provide adequate holding power when engaged.

When other brake systems, such as the service brake, are tested, they are typically evaluated while the vehicle is in motion to assess their performance in stopping the vehicle. The hydraulic and emergency brake systems also have specific operational testing procedures that generally involve the vehicle being in different states of motion or readiness. Thus, the parking brake remains the only system primarily tested in a stopped condition to ensure that it can securely hold the vehicle in place.