Chevrolet Silverado / GMC Sierra. Service manual — part 1570

14. Install the brake drum. Refer to Brake Drum Replacement.

15. Enable the park brake cable automatic adjuster. Refer to Parking Brake Cable Adjuster

Enabling .

16. If necessary, adjust the park brake cable tension. Refer to Park Brake Adjustment (Drum

Brake) or Park Brake Adjustment (Disc Brake) .

17. Install the tire and wheel. Refer to Tire and Wheel Removal and Installation .

18. Lower the vehicle.

DESCRIPTION AND OPERATION

DRUM BRAKE SYSTEM DESCRIPTION AND OPERATION

System Component Description

The drum brake system consists of the following:

Drum Brake Shoes

Applies mechanical output force (from hydraulic brake wheel cylinders) to friction surface
of brake drums.

Brake Drums

Uses mechanical output force applied to friction surface from drum brake shoes to slow
speed of tire and wheel assembly rotation.

Drum Brake Hardware

Secures drum brake shoes firmly in proper relationship to hydraulic brake wheel cylinders.
Enables sliding motion of brake shoes needed to expand toward friction surface of drums
when mechanical output force is applied; provides return of brake shoes when mechanical
output force is relieved.

Drum Brake Adjusting Hardware

Provides automatic adjustment of brake shoes to brake drum friction surface whenever
brake apply occurs during rearward motion of the vehicle.

System Operation

Mechanical output force is applied from the hydraulic brake wheel cylinder pistons to the top of

2008 Chevrolet Silverado 1500

2008 BRAKES Drum Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

the drum brake shoes. The output force is then distributed between the primary and secondary
brake shoes as the shoes expand toward the friction surface of the brake drums. The brake shoes
apply the output force to the friction surface of the brake drums, which slows the rotation of the
tire and wheel assemblies. The proper function of both the drum brake hardware and adjusting
hardware is essential to the proper distribution of braking force.

SPECIAL TOOLS AND EQUIPMENT

SPECIAL TOOLS

Illustration

Tool Number/ Description

J 21177-A

Drum to Brake Shoe Clearance Gage

J 38400

Brake Shoe Spanner & Spring Remover

J 41013

Rotor Resurfacing Kit

2008 Chevrolet Silverado 1500

2008 BRAKES Drum Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

J 42450-A

Wheel Hub Resurfacing Kit

J 8001

Dial Indicator Set

2008 Chevrolet Silverado 1500

2008 BRAKES Drum Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

2008 GENERAL MOTORS

Sierra & Silverado

BUZZERS, RELAYS & TIMERS

BUZZERS, RELAYS & TIMERS LOCATION

Component

Location

A/C CMPRSR Relay

In underhood fuse block. See Fig. 62.

Auxiliary Battery Relay (4)

Rear of engine compartment. See Fig.

80.

Emergency Vehicle Roof Lamp Relay (5)

In roof console. See Fig. 100.

ENG EXH VLV Relay

In underhood fuse block. See Fig. 62.

FAN CNTRL Relay

In underhood fuse block. See Fig. 62.

FAN HI Relay

In underhood fuse block. See Fig. 62.

FAN LO Relay

In underhood fuse block. See Fig. 62.

FAN RLY Relay

In underhood fuse block. See Fig. 62.

FOG LAMP Relay

In underhood fuse block. See Fig. 62.

FUEL PMP Relay

In underhood fuse block. See Fig. 62.

Fuel Pump (FP) Relay (Secondary) (3)

Left side of engine compartment. See

Fig. 103.

HDLP LO/HID Relay

In underhood fuse block. See Fig. 62.

Integrated Trailer Brake Controller Solid State
Relay

On rear of left frame rail. See Fig. 44.

PRK LAMP Relay

In underhood fuse block. See Fig. 62.

PWR/TRN Relay

In underhood fuse block. See Fig. 62.

REAR DEFOG Relay

In underhood fuse block. See Fig. 62.

Roof Beacon Relay (11)

In overhead console. See Fig. 99.

RUN/CRNK Relay

In underhood fuse block. See Fig. 62.

Run Relay (2)

Right rear of engine compartment. See

Fig. 80.

STRTR Relay

In underhood fuse block. See Fig. 62.

Trailer Brake Controller Solid State Relay (20/30
Series) (3)

Left rear frame rail. See Fig. 107.

Trailer Brake Controller Solid State Relay (31
Series) (1)

On left frame rail. See Fig. 108.

2008 Chevrolet Silverado 1500

2008 GENERAL MOTORS Sierra & Silverado

2008 Chevrolet Silverado 1500

2008 GENERAL MOTORS Sierra & Silverado