What does a brake light check typically indicate?

A brake light check typically indicates issues with trailer use, particularly the functionality of the trailer's braking system in relation to the vehicle's brake lights. When towing a trailer, the braking system needs to be properly calibrated so that the brake lights on both the towing vehicle and the trailer work in harmony. If there are malfunctions or if the trailer's brakes are not functioning effectively, it could trigger alerts related to brake light operations. This highlights the importance of ensuring that the entire braking system, including the connections between the vehicle and the trailer, is working correctly for safety.

In contrast, the other options pertain to different aspects of the vehicle's brake system maintenance and do not directly relate to a brake light check. For example, the need for brake fluid replacement, worn-out brake pads, and the necessity for a brake system flush involve internal components and maintenance levels rather than external indicators like brake lights.