What indicates a problem when testing the stopping action of service brakes on a hydraulic system?

Testing the stopping action of service brakes in a hydraulic system is crucial for vehicle safety. When the brake pedal goes to the floor, it indicates a significant issue within the brake system, such as a leak in the hydraulic lines, worn brake pads, or air in the brake lines. This condition compromises the ability of the brakes to create adequate stopping power, making it potentially dangerous to operate the vehicle.

In contrast, a firm brake pedal suggests that the hydraulic system is functioning correctly, allowing for effective braking. A vehicle that stops immediately is optimal, as it indicates a responsive brake system. Additionally, when a vehicle tracks straight while braking, it indicates that the braking force is being evenly applied across the wheels, which is desirable for maintaining control and stability. Thus, the condition of the brake pedal reaching the floor is a clear signal that there is a significant malfunction requiring immediate attention.