System Component Description

The brake booster vacuum assist system consists of the following:

Brake Booster Auxiliary Vacuum Pump:  The brake booster auxiliary vacuum pump is an electrical vacuum pump mounted behind the radiator on the chassis in the engine bay. When the engine vacuum drops below a predetermined threshold the brake booster auxiliary vacuum pump is switched ON by the engine control module. Optimum vacuum pressure is hereby maintained at the vacuum brake booster to enhance braking assistance.

Vacuum Source: Vacuum is supplied during normal engine operation and is enhanced by the operation of the brake booster auxiliary vacuum pump. This additional vacuum is used by the brake booster to enhance braking assistance when the engine control module commands.

System Operation

The engine control module (ECM) actuates the brake booster vacuum pump to generate additional vacuum to the vacuum brake booster during catalytic convertor light up. During catalytic convertor light-up, insufficient vacuum is generated by the engine to reduce brake pedal effort. The vacuum pump supplements the lack of vacuum in the brake booster during catalytic convertor light-up.