Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Active Brake Booster
The active brake booster is similar to a conventional vacuum assisted brake booster with the addition of a brake booster solenoid, a brake booster travel sensor, and a vacuum pressure sensor. If it is necessary to apply the friction brakes due to inadequate deceleration from regenerative braking, the ABS module will send a PWM voltage to the brake booster solenoid that is proportional to the amount of brake torque requested. The booster solenoid will open, which allows the vacuum booster push rod to push on the master cylinder creating pressure in the hydraulic system.
The ABS module uses the signals produced by the vacuum pressure sensor to verify that vacuum maintained in the brake booster. The ABS module uses the signals produced by the brake booster travel sensor to monitor brake booster performance. The brake booster travel sensor and the vacuum pressure sensor can be serviced separately from the brake booster.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.