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Chevrolet Silverado / GMC Sierra. Manual - part 2396
steering pump (8).
BRAKE ASSIST SYSTEM DESCRIPTION AND OPERATION (VACUUM ASSIST)
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.
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 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
Brake system input force 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
vacuum brake booster.
Active Brake Booster
Incorporated into the vacuum brake booster, is an electric solenoid actuator. This actuator can be
used to apply the brake booster and thus the master cylinder as commanded by the electronic
brake control module (EBCM). During stability events, the EBCM can command the solenoid
2008 Chevrolet Silverado 1500
2008 BRAKES Hydraulic Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
actuator in the brake booster to apply the booster. This quickly provides a large volume of
pressurized brake fluid to the brake pressure modulator valve (BPMV). The BPMV will then
control the flow of fluid to the brake corners to obtain the appropriate response for the vehicle.
SPECIAL TOOLS AND EQUIPMENT
SPECIAL TOOLS
Illustrations
Tool Number/Description
J 26889
Accumulator Piston Compressor
J 28662
Brake Pedal Effort Gauge
J 29532
Diaphragm Pressure Bleeder
2008 Chevrolet Silverado 1500
2008 BRAKES Hydraulic Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
J 35589-A
Brake Pressure Bleeder Adapter
J 45405
Brake Pipe Flaring Tool
2008 Chevrolet Silverado 1500
2008 BRAKES Hydraulic Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
2008 ACCESSORIES & EQUIPMENT
Instrument Panel and Console Trim - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra
& Silverado
SPECIFICATIONS
FASTENER TIGHTENING SPECIFICATIONS
Application
Specification
Metric
English
Front Floor Console Armrest Screws
2 N.m
18 lb in
Front Floor Console Compartment Screws
2 N.m
18 lb in
Front Floor Console Cupholder Screws
2 N.m
18 lb in
Front Floor Console End Panel Screws
2 N.m
18 lb in
Front Floor Console Inner Cover Screws
2 N.m
18 lb in
Front Floor Console Latch Inner Screws
2 N.m
18 lb in
Front Floor Console Latch Outer Screws
2 N.m
18 lb in
Instrument Panel Accessory Switch Screws
2 N.m
18 lb in
Instrument Panel Carrier Bolts
9 N.m
80 lb in
Instrument Panel Carrier Support Bolts
22 N.m
16 lb ft
Instrument Panel Carrier Support Lower Bolt
(w/RPO SLT)
2 N.m
18 lb in
Instrument Panel Cluster Screws
2 N.m
18 lb in
Instrument Panel Center Support Bracket Bolt
22 N.m
16 lb ft
Instrument Panel Cluster Trim Panel Screws
(w/RPO SLT)
2 N.m
18 lb in
Instrument Panel Cluster Trim Plate Cover Screws
2 N.m
18 lb in
Instrument Panel Compartment Screws
2 N.m
18 lb in
Instrument Panel Compartment Latch Screws
2 N.m
18 lb in
Instrument Panel Compartment Door Screws
(w/RPO SLT)
2 N.m
18 lb in
Instrument Panel Compartment Striker Screws
2 N.m
18 lb in
Instrument Panel Insulator Screws
2 N.m
18 lb in
Instrument Panel Knee Bolster Deflector Nuts
9 N.m
80 lb in
Instrument Panel Knee Bolster Screws
2 N.m
18 lb in
Instrument Panel Lower Trim Panel Screws
2 N.m
18 lb in
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Instrument Panel and Console Trim - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Instrument Panel and Console Trim - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
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