Which of these should be tested while the vehicle is stopped?

The parking brake should be tested while the vehicle is stopped. It’s crucial to ensure that the parking brake functions effectively to secure the vehicle when it is not in operation. This testing usually involves engaging the parking brake and ensuring that the vehicle remains stationary, which helps confirm that the brake holds the vehicle in place on various inclines.

In contrast, the service brake is typically tested while the vehicle is in motion to assess its responsiveness and braking capabilities under driving conditions. The hydraulic brake system requires the vehicle to be operational for a full assessment of its performance, as it involves the vehicle moving and stopping to validate its effectiveness. Lastly, the anti-lock brake system is also evaluated during specific driving situations to confirm that it prevents wheel lockup during hard braking, which cannot be effectively tested while the vehicle is stationary.