Opel Insignia: Description and Operation

Brake Assist System Description and Operation

System Component Description

The brake assist system consists of the following:

Brake Pedal

Receives, multiplies and transfers brake system input force from driver.

Brake Pedal Pushrod

Transfers multiplied input force received from brake pedal to brake booster.

Vacuum Brake Booster

Uses source vacuum to decrease effort required by driver when applying brake system input force.

At rest, source vacuum is applied to both sides of the vacuum diaphragm for single boosters, or to both sides of each of the diaphragms for tandem boosters. Return springs maintain the booster in a rest position.

When brake system input force is applied, vacuum to the rear of the diaphragm(s) is cut off, and air at atmospheric pressure is admitted in its place. This provides a decrease in brake pedal effort required. When input force is removed, vacuum again replaces atmospheric pressure within the booster.

Vacuum Source

Supplies force used by vacuum brake booster to decrease brake pedal effort.

The primary source for vacuum is typically the vehicle's internal combustion engine. Some vehicles may use a vacuum pump to ensure and adequate supply of vacuum under various operating conditions, such as during cold start-up, heavy throttle, and high altitude.

Vacuum Monitoring System

Provides a feedback voltage signal relative to the amount of vacuum available for the vacuum power brake booster.

This typically consists of a vacuum sensor mounted either into the power vacuum brake booster, integrated with the vacuum check valve, or in-line within the vacuum hose. The sensor feedback is typically monitored by the powertrain control module(s).

Vacuum Source Control

If equipped with a system to monitor available levels of vacuum for the brake assist system, the powertrain control module(s) typically perform the primary monitoring function.

The powertrain controller will typically monitor the feedback signal of a vacuum sensor, as it relates to available vacuum at the vacuum power brake booster. The powertrain controller uses the information to make sure available vacuum remains above predetermined levels. If additional vacuum is required, the powertrain controller may reactivate engine cylinders, if equipped, or command a vacuum pump ON, if equipped, and/or may alter the operation of various other engine controls and devices, as necessary.

Vacuum Source Delivery System

Enables delivery and retention of source vacuum for vacuum brake booster.

This typically consists of a vacuum check valve and a vacuum hose or pipe. If a vacuum pump is used, additional check valves may be used.

System Operation

Brake system input force from the driver is multiplied by the brake pedal and transferred by the pedal pushrod to the hydraulic brake master cylinder. Effort required to apply the brake system is reduced by the operation of the vacuum brake booster.

When brake system force is applied, vacuum to the rear of the diaphragm(s) is cut off, and air at atmospheric pressure is admitted in its place. The vacuum acts to pull the diaphragm(s) forward, while the atmospheric pressure acts to push from behind. As a result, the amount of effort required by the driver is reduced. When input force is removed, vacuum again replaces atmospheric pressure within the vacuum power brake booster to help return the booster to rest.

If the vehicle is equipped with a vacuum monitoring system, the powertrain control module(s) typically will alter powertrain functions and/or command the vacuum pump ON, if equipped, to provide for the vacuum needs of the brake assist system, as operating conditions warrant.

Brake Booster Vacuum Assist Description and Operation

System Component Description

B19B - B19B Brake Booster Vacuum Sensor
K17 - K17 Electronic Brake Control Module
M9 - M9 Brake Booster Pump Motor

The brake booster vacuum assist system consists of the following:

Brake Booster Auxiliary Vacuum Pump (electric or mechanical)

The brake booster vacuum pump is a secondary vacuum supply to the brake booster used to maintain sufficient vacuum for brake assist.

Brake Booster Vacuum Sensor

The vacuum sensor is used to measure the level of vacuum available in the brake booster. The electronic brake control module supplies a 5 V reference and a low reference circuit to the brake booster vacuum sensor. The vacuum sensor is located in the brake booster or vacuum hose. The brake booster vacuum sensor supplies a voltage signal in relation to the pressure in the brake booster to the electronic brake control module.

Electronic Brake Control Module

The electronic brake control module monitors the vacuum in the brake booster using the brake booster vacuum sensor. When the vacuum within the system drops the electronic brake control module turns ON the brake booster auxiliary vacuum pump.

Vacuum Brake Booster

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 the atmospheric pressure within the booster. The booster uses source vacuum to decrease the effort required by driver when applying the brake.

Vacuum Source

Vacuum is supplied by the engine vacuum or by the brake booster auxiliary vacuum pump (electric or mechanical).

System Operation

The electric pump can be switched on and off by the electronic brake control module based on the required vacuum. Pressure variations during braking can be measured, and the pump can be activated to generate additional vacuum if required to increase the braking force.

BRAKE FLUID AND BRAKE FLUID HANDLING

WARNING: Brake fluid may irritate eyes and skin. In case of contact, take the following actions:

• Eye contact - rinse thoroughly with water.
• Skin contact - wash with soap and water.
• If ingested - consult a physician immediately.

CAUTION: When adding fluid to the brake fluid reservoir or to the clutch fluid reservoir, use only DOT-4+ brake fluid from a clean, sealed container. This polyglycol brake fluid is hygroscopic and absorbs moisture. Do not use fluid from an open container that may be contaminated with water. Improper or contaminated fluid could result in damage to the system components. CAUTION: Brake fluid will damage electrical connections and painted surfaces. Use shop cloths, suitable containers, and fender covers to prevent brake fluid from contacting these areas. Always re-seal and wipe off brake fluid containers to prevent spills. CAUTION: Avoid spilling brake fluid on any of the vehicle's painted surfaces, wiring, cables or electrical connectors. Brake fluid will damage paint and electrical connections. If any fluid is spilled on the vehicle, immediately flush the area with water to minimize the potential for damage. CAUTION: Power steering fluid, engine oil, brake fluid, or any mineral based fluids cannot be mixed. If brake seals contact power steering fluid or steering seals contact brake fluid, seal damage will result.

NOTE:

• Do not reuse the brake fluid collected during the hydraulic brake system bleeding.
• Always store brake fluid in a closed container.
• Reseal brake fluid containers immediately after use.
• Do not use brake fluid left in an open container.
• Do not use brake fluid left in an improperly sealed container.
• Do not use the following fluids in the hydraulic brake system:
  • Power steering fluid
  • Automatic transmission fluid
  • DOT 5 silicone hydraulic brake fluid

BRAKE WARNING SYSTEM DESCRIPTION AND OPERATION

Brake Warning Indicator

P16 - P16 Instrument Cluster
B20 - B20 Brake Fluid Level Switch
K17 - K17 Electronic Brake Control Module

The instrument cluster turns the brake warning indicator ON when the following occurs:

• The instrument cluster performs the bulb check. The brake warning indicator illuminates for 5 s.
• When the electronic brake control module (EBCM) detects low brake fluid level it sets DTC C0267 and sends a serial data message to the instrument cluster, which will illuminate the red brake indicator.

Driver Information Center Messages

When the electronic brake control module (EBCM) detects low brake fluid level it sets DTC C0267 and sends a serial data message to the driver information center, which will display Brake Fluid Low message.

Hydraulic Brake System Description and Operation

System Component Description

The hydraulic brake system consists of the following:

Hydraulic Brake Master Cylinder Fluid Reservoir

Contains supply of brake fluid for the hydraulic brake system.

Hydraulic Brake Master Cylinder

Converts mechanical input force into hydraulic output pressure.

Hydraulic output pressure is distributed from the master cylinder through two hydraulic circuits, supplying diagonally-opposed wheel apply circuits.

Hydraulic Brake Pressure Balance Control System

Regulates brake fluid pressure delivered to hydraulic brake wheel circuits, in order to control the distribution of braking force.

Pressure balance control is achieved through dynamic rear proportioning (DRP), which is a function of the ABS modulator. Refer to ABS Description and Operation for specific information on the operation of DRP.

Hydraulic Brake Pipes and Flexible Brake Hoses

Carries brake fluid to and from hydraulic brake system components.

Hydraulic Brake Wheel Apply Components

Converts hydraulic input pressure into mechanical output force.

System Operation

Mechanical force is converted into hydraulic pressure by the master cylinder, regulated to meet braking system demands by the pressure balance control system, and delivered to the hydraulic brake wheel circuits by the pipes and flexible hoses. The wheel apply components then convert the hydraulic pressure back into mechanical force which presses linings against rotating brake system components.

SPECIAL TOOLS AND EQUIPMENT

SPECIAL TOOLS

CH 28662

J 28662

Brake Pedal Effort Gauge

CH 29532- B

J 29532-B

Pressure Brake Bleeder, or equivalent

CH 35798

J 35798

Brake Pressure Bleeder Adapter

CH 45405

J 45405

Brake Pipe Flaring Kit

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