Determining If Your Brake Booster Has Failed - Grafco Electric

Nov 1, 2018


Are you experiencing issues with your vehicle's brake system? Determining whether your brake booster has failed is crucial for ensuring the safety of your ride. Grafco Electric is here to provide you with a comprehensive guide to help you identify the signs and symptoms of a malfunctioning brake booster.

What is a Brake Booster?

A brake booster, also known as a vacuum booster, is a device that assists in multiplying the force exerted on the brake pedal, making it easier to apply the brakes. It works by using vacuum pressure generated by the engine to amplify the force applied to the master cylinder, resulting in more efficient braking power.

Signs of a Failed Brake Booster

Identifying a failed brake booster can be challenging, but there are clear signs to look out for. If you experience any of the following symptoms, it may be an indication of a malfunctioning brake booster:

  • Hard Brake Pedal: A stiff brake pedal that requires excessive force to engage the brakes is a common sign of a failed brake booster.
  • Increased Stopping Distance: If your vehicle takes longer to stop or needs more distance to come to a complete halt, it could be due to a brake booster issue.
  • Inconsistent Brake Response: An unpredictable brake response, such as brakes engaging suddenly or feeling spongy, might be caused by a malfunctioning brake booster.
  • Reduced Braking Power: Insufficient braking force, even when the pedal is fully engaged, can indicate a failing brake booster.
  • Engine Trouble: In some cases, a failing brake booster may cause engine performance issues, such as stalling or erratic idle.

Determining Brake Booster Failure

While the signs mentioned above can indicate a failed brake booster, it is necessary to perform a few tests to confirm the issue. Here are a couple of methods to determine if your brake booster has indeed failed:

Vacuum Test Method

The vacuum test method helps assess whether the brake booster is retaining vacuum pressure effectively. To perform this test:

  1. With the engine off, pump the brake pedal several times to deplete any remaining vacuum pressure.
  2. Hold the brake pedal down and start the engine. Observe if the pedal sinks slightly and then becomes firm. If it does, the brake booster is likely functioning correctly. However, if the pedal remains hard or drops to the floor, it indicates a failed brake booster.

Brake Pedal Force Method

The brake pedal force method assesses the resistance applied when pressing the brake pedal. To perform this test:

  1. Start the engine and ensure it is running at idle speed.
  2. Press the brake pedal with moderate force while the vehicle is stationary. If the pedal falls noticeably after initial resistance and requires less force to engage, it may indicate a failed brake booster.
  3. Next, with the engine still running, perform the same test while putting additional pressure on the brake pedal. If the pedal becomes significantly easier to press, this could be another sign of a faulty brake booster.

Seek Professional Assistance

If you suspect that your brake booster has failed based on the signs and tests, it is recommended to seek professional assistance immediately. Attempting to repair or replace the brake booster without adequate knowledge and experience can be dangerous and compromise your safety on the road. Grafco Electric has a team of skilled technicians who specialize in brake system diagnostics and repairs. Contact us today to schedule an appointment and restore the optimal functionality of your brake booster.


Determining if your brake booster has failed is crucial for maintaining the safety and performance of your vehicle. By understanding the signs and symptoms mentioned in this comprehensive guide provided by Grafco Electric, you can take appropriate measures to address any brake booster issues promptly. Remember, the proper functioning of your brake system is essential for your safety on the road. Don't hesitate to reach out to Grafco Electric's experienced team for professional assistance and reliable brake system services.

Raniero Iraci
This guide by Grafco Electric is a lifesaver! 💯 Keep your ride safe and sound!
Nov 11, 2023
Nancy Jagielski
This guide from Grafco Electric is essential for identifying signs of a failed brake booster. Keep your ride safe!
Oct 6, 2023