What causes the brake light to come on?

[LaDaniel]

The reasons for the constant illumination of the brake indicator light are as follows: 1. Handbrake not released: If the handbrake is not released or not fully released, it will cause the brake indicator light to stay on, reminding the driver to release the handbrake before starting. 2. Insufficient brake fluid: Low brake fluid levels can affect the vehicle's braking performance and driving safety. 3. Leakage in brake master cylinder or brake lines: If brake fluid has been recently topped up but the vehicle still shows low brake fluid levels, check for leaks in the brake master cylinder or lines. 4. Air in the brake system: If you feel weak braking or insufficient braking force when applying the brakes, it indicates air in the brake system. In this case, check for air leaks in the vacuum booster pump. 5. Worn brake pads: Severely worn brake pads can reduce braking performance and, in severe cases, cause the vehicle to completely lose braking function.