For 1990-2009 cars

### System Component Description

The brake booster vacuum assist system with 2.0L turbocharger (RPO LNF) consists of the following:

Brake Booster Pump Motor: Supplies vacuum used by brake booster to increase vacuum in the brake booster assemble.
Brake Booster Vacuum Sensor: The brake booster vacuum sensor monitors the vacuum levels in the brake booster, and signals the engine control module (ECM) to command the brake booster pump motor on.
Vacuum Brake Booster: Uses source vacuum to decrease effort required by driver when applying brake system input force. When brake system input force is applied, air at atmospheric pressure is admitted to the rear of both vacuum diaphragms, providing a decrease in brake pedal effort required. When input force is removed, vacuum replaces atmospheric pressure within the booster.
Vacuum Pump Relay: Supplies battery voltage used by brake booster pump motor to decrease vacuum in the brake booster assemble.
Vacuum Source: Supplies force used by vacuum brake booster to decrease brake pedal effort.
Vacuum Source Delivery System: Enables delivery and retention of source vacuum for vacuum brake booster.

### System Operation

The brake booster vacuum assist is an auxiliary vacuum source for the brake assist system, if the vehicle is equipped with 2.0 L turbo charged system (RPO LNF) only. The brake booster vacuum assist auxiliary pump motor creates vacuum in the brake booster assembly to assist in vacuum loss or low vacuum caused from the turbocharger operating conditions. The advantage of having the vacuum generated by an auxiliary pump is that the brake system then manages the amount of vacuum, thus amplification, with the braking system operation becoming independent of the engine's. Pressure variations during braking are measured with the vacuum sensor in the vacuum brake booster, and the pump activated to generate additional vacuum if required to increase braking force.