Power Brake Assist: Description and Operation

Electric Vacuum Pump System Description

System Requirement

Due to the addition of the turbocharger, the intake manifold vacuum can be reduced affecting the brake boost. To compensate for this loss of vacuum, the electric vacuum pump is required.

- During cold engine starting; the fuel and emission system retards the ignition timing to help heat up the catalytic converter and the turbocharger with high exhaust temperature. In this case, the vacuum pressure in the intake manifold is reduced, especially in high altitude areas where low atmospheric density conditions create a long warm up condition.
- When the turbocharger system turbochargers the intake air, the intake manifold vacuum is reduced.

System Control

The electric vacuum pump controls the target vacuum of the brake booster compared to atmospheric pressure.






System Electrical Structure

The system has a brake booster pressure sensor, an electric vacuum pump, a electric vacuum pump system indicator in the gauge control module, and the PCM with fuel and emission systems sensors.






System Air Flow

The brake system includes these components: A brake booster pressure sensor, an electric vacuum pump with a filter, a check valve (vacuum pump), and a 3-way joint on the conventional brake system booster vacuum hoses.






Electric Vacuum Pump

The electric vacuum pump has a motor and a rotor with five sliding vanes. The motor rotates the rotor, which generates the vacuum.

The motor function is controlled by the PCM.

Brake Booster Pressure Sensor

The brake booster pressure sensor converts brake booster absolute pressure into electrical signals to the PCM.

PCM (Electric Vacuum Pump System) Inputs and Outputs at Connector A (square) (44P)











PCM (Electric Vacuum Pump System) Inputs and Outputs at Connector B (triangle) (44P)











PCM (Electric Vacuum Pump System) Inputs and Outputs at Connector C (circle) (44P)