Why does the brake suddenly become hard and difficult to press while driving?

[LaChristian]

When the brake suddenly becomes hard and difficult to press while driving, it is usually related to a vacuum booster pump failure. Here are the reasons and solutions for a hard brake: 1. Vacuum booster pump air leakage: Under normal driving conditions, the negative pressure in the intake manifold absorbs air from the vacuum booster pump, keeping it in a charged state. If the brake becomes hard on the first press, it indicates air leakage in the vacuum booster pump. Solution: Replace the vacuum hose. 2. Speed too low, gear too high: Under normal driving conditions, the negative pressure in the intake manifold absorbs air from the vacuum booster pump, keeping it in a charged state. If the brake becomes hard after pressing it once, it may be due to insufficient intake negative pressure caused by low speed and high gear. Solution: Increase speed. 3. Leakage in the connecting hose: A leaking hose can lead to insufficient vacuum, causing the brake to lose its boosting effect and become hard. Solution: Check the vacuum hose to ensure it is properly sealed and restore normal operation.