What component warns drivers of issues within the brake system?

The combination valve plays a crucial role in monitoring the brake system's functionality. It integrates multiple functions, including pressure regulation and warning the driver of potential issues. If there is a problem with the brake system, such as a significant drop in brake fluid pressure, the combination valve can trigger a dashboard warning light. This alert notifies the driver that there may be a malfunction, allowing for timely intervention to prevent brake failure.

In the context of the other options, while brake pads are essential for the actual braking process by providing the friction necessary to stop the vehicle, they do not directly warn about system issues. The ABS module is responsible for managing the anti-lock braking system, which helps to prevent wheel lock-up during braking. Although it may contribute to overall brake system safety, the ABS module primarily functions to enhance braking performance rather than alert to brake problems. The brake fluid reservoir holds brake fluid but does not serve as a direct warning system. While low fluid levels may indicate a potential issue, the combination valve is specifically designed to alert the driver to problems within the brake system effectively.