Description And Operation: Operation

The vacuum pump is installed to provide supplemental vacuum to the brake booster to compensate for lower engine vacuum. The vacuum pump is connected to the engine and the brake booster through a series of hoses and one-way flow check valves. A pressure sensor, mounted in the brake booster, provides information to the Antilock Brake System (ABS) module, then the vacuum level is sent over Controller Area Network (CAN) to the Powertrain Control Module (PCM). The PCM modulates the vacuum pump operation to maintain the brake booster vacuum within a given range. This system ensures that the customer experiences a consistent brake pedal feel under all driving conditions.

A two wire electrical connector is used to supply power and ground for the vacuum pump. Operating voltage is between 9V - 16V. Control of the vacuum pump is provided by the PCM using a low side driver to a normally open relay (coil side). The relay coil side power is from a fuse in the under hood Power Distribution Center (PDC). The switched power circuit to the vacuum pump relay is wired directly from the battery through an inline fuse holder located below the remote battery post connection on the RH side in the engine compartment. The relay is located on the LH shock tower in the engine compartment.

The PCM monitors the Manifold Absolute Pressure (MAP) sensor and when the signal indicates low engine vacuum the PCM will cycle the vacuum pump as necessary to add vacuum to the power brake booster. The vacuum hoses are connected between the vacuum pump, the engine manifold (for MAP sensor signal), and the power brake booster vacuum sensor (on the brake booster). When the PCM cycles the vacuum pump on, the PCM monitors the MAP sensor and if the vacuum signal does not indicate a rising vacuum then DTCs will be set. Additionally, the ABS module monitors the vacuum at the brake booster vacuum sensor and DTCs will also set in the ABS module.