What Causes the Brake Pedal to Be Hard to Press and the Car Unable to Start?

[Braxton]

Here are the reasons why the brake pedal is hard to press and the car cannot start: 1. Vacuum booster pump leakage: If the car's vacuum booster pump leaks or malfunctions, the force required to press the brake pedal increases because the brake booster is not functioning properly. If it fails, the brake loses its power assistance, making it difficult to press. 2. Normal phenomenon: The inability to press the brake pedal after the engine is turned off is related to the brake booster pump. The brake booster pump only continuously generates vacuum when the engine is running. When the engine is off, it relies on the remaining vacuum assistance, but this will restore once the engine starts, and it is not a malfunction. Additional info: In driving, to prevent unexpected situations like sudden movement or rolling when starting the car, automatic transmission models are designed to require pressing the brake pedal to start. If the brake pedal is not pressed, the car will not start successfully. Moreover, the gear must be in P (Park) or N (Neutral) when starting an automatic transmission car. If started in N without the handbrake engaged, the car may roll. Therefore, the "press brake to start" design is entirely for safety considerations.

[VanFinn]

Last time I was driving, I also encountered the brake pedal being hard to press and the car wouldn't start, which made me really nervous. Experience tells me this might be an issue with the vacuum booster pump. After the car is turned off, the vacuum provided by the engine disappears, causing the booster system to fail and the brake to become hard. Alternatively, it could be due to air leakage in the pipes leading to insufficient vacuum. Failure to start is often related to the battery—if the battery is old and the voltage is low, it can't power the starter. Also, check the brake light switch—many newer car models require pressing the brake to start, and if the switch is damaged, no signal is transmitted. I suggest first trying to turn on the headlights to see if they work, and after turning off the engine, press the brake pedal a few times to listen for any air leakage sounds. For safety, avoid forcing any operations and promptly contact a repair shop to check the vacuum pump and electrical connections to prevent delays or accidents during your trip.