Chevrolet Silverado / GMC Sierra. Manual — part 2759

time will activate only the seat back heater element in the high mode. Each time the seat back
button is pressed the seat back heat level is reduced from high to medium, low, and off. During
heated seat operation the heat zone operating mode may be changed without affecting the current
heat level mode.

The heated seat switches are momentary contact switches and are inputs to the driver and
passenger door switches. A ground circuit is connected to the switch assembly through the door
switch, and when a heated seat switch is pressed and released a brief switch signal is supplied to
the door switch. Whenever the door module receives an active heated seat switch input, the active
switch signal is sent to the memory seat module as a GMLAN message. The memory seat module
determines the heated seat mode based on the switch messages and sends a message to the door
switch to display the heated seat indicators as necessary.

The memory seat module controls the voltage supply and the ground circuits to the seat heater
elements. When a heated seat function is commanded active, the seat module will switch battery
voltage to the heater element supply circuits, and ground is provided through pulse width
modulation (PWM) low side drive control circuits. During heated seat operation both the seat
back and cushion heater elements are supplied battery voltage. The seat module grounds the
appropriate control circuits for back only or back and cushion heating modes, and opens or closes
the active control circuits as necessary in order to maintain the desired seat temperature. The seat
module relies on 4 independent inputs from thermistors located in the seat back and seat cushion
of the driver and passenger seats to control heated seat temperatures. The thermistors are 2-wire
sensors supplied with a 5-volt referenced signal circuit and a low reference circuit from the seat
module. Resistance through the thermistors varies with temperature causing the heated seat sensor
signal circuit voltage levels to decrease as the seat back temperatures rise.

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Seat Heating and Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

2008 STEERING

Steering Linkage - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

SPECIFICATIONS

FASTENER TIGHTENING SPECIFICATIONS

REPAIR INSTRUCTIONS

STEERING LINKAGE INSPECTION

Tools Required

J 45101 Hub and Wheel Runout Gage

J 42640 Steering Column Anti-Rotation Pin

Inspection

1. Elevate the left front of the vehicle and install suitable vehicle support maintaining contact

between the right front tire/wheel assembly and the shop floor.

Application

Specification

Metric

English

Idler Arm Nut (at the Relay Rod)

62 N.m

46 lb ft

Idler Arm Nut (at the Vehicle Frame)

105 N.m

78 lb ft

Pitman Arm Nut (at the Relay Rod)

62 N.m

46 lb ft

Pitman Arm Nut (at the Steering Gear)

250 N.m

184 lb ft

Steering Linkage Shock Absorber Nut

40 N.m

30 lb ft

Steering Linkage Inner Tie Rod

100 N.m

74 lb ft

Steering Linkage Outer Tie Rod Nut

60 N.m

44 lb ft

2008 Chevrolet Silverado 1500

2008 STEERING Steering Linkage - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

2008 Chevrolet Silverado 1500

2008 STEERING Steering Linkage - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Fig. 1: Identifying J 42640
Courtesy of GENERAL MOTORS CORP.

2. Position the wheels in a straight-ahead position and install anti-rotation pin J 42640 .

2008 Chevrolet Silverado 1500

2008 STEERING Steering Linkage - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Fig. 2: Installing Dial Indicator Between Outer Tie Rod And Steering Knuckle
Courtesy of GENERAL MOTORS CORP.

3. Install a dial indicator between the steering linkage outer tie rod and the steering knuckle as

shown and push slowly inward with one hand to remove the lash.

4. Place the dial indicator at zero, pull outward on the tire, and note the amount of movement

in the joint.

The movement should not exceed 1.0 mm (0.039 in).

2008 Chevrolet Silverado 1500

2008 STEERING Steering Linkage - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado