Brake Booster Vacuum Sensor

The Brake Booster Vacuum (BBV) sensor measures vacuum level in brake booster converts it to a voltage signal. The PCM reads this voltage signal and converts it back to a vacuum level. The BBV sensor is very similar to a MAP sensor except for one very important difference. The BBV sensor signal is an indication of vacuum instead of pressure as vacuum in brake booster increases (pressure decreases), voltage signal increases.

The BBV sensor parameter (PD84) also displays a vacuum level, so a low reading indicates low vacuum (near atmospheric pressure) in brake booster and a high reading indicates high vacuum in brake booster. The brake booster vacuum signal is used to control engine torque output while brakes are applied.