In a hydraulic system, what is a sign that indicates the system is functioning properly during the power reserve test?

In a hydraulic system, particularly in the context of brake systems, a slight fall of the brake pedal when the engine starts indicates that the system is functioning properly. This is because the engine's power assist mechanism is engaging, providing additional force to the brake system.

When the engine starts, the vacuum or pressure assist from the engine contributes to the braking system's ability to operate smoothly and effectively. A slight drop in the brake pedal is expected as it signifies that the hydraulic pressure is being properly applied and the brake booster is working as intended. This behavior confirms that the connection between the engine and the brake system is functioning, allowing for enhanced brake operation.

If the pedal were to remain steady regardless of the engine's status, it could suggest a malfunction in the system, such as a lack of assistance which could lead to difficulty in braking. Similarly, a pedal that does not move at all is not appropriate since it lacks the normal response one would expect from a properly functioning hydraulic brake system. Any unusual noises, such as clicking when the pedal is pressed, often indicate mechanical issues rather than normal operational behavior.