Chevrolet Silverado / GMC Sierra. Service manual — part 2770

2008 ACCESSORIES & EQUIPMENT

Sunroof - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

SPECIFICATIONS

FASTENER TIGHTENING SPECIFICATIONS

SCHEMATIC AND ROUTING DIAGRAMS

SUNROOF SCHEMATICS

Application

Specifications

Metric

English

Sunroof Actuator to Bracket Screws

3 N.m

27 lb in

Sunroof Air Deflector Screws

3 N.m

27 lb in

Sunroof Module

10 N.m

89 lb in

Sunroof Water Tray to Sunroof Module Screws

1 N.m

9 lb in

Sunroof Window to Module Screws

3 N.m

27 lb in

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Sunroof - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Sunroof - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Fig. 1: Sunroof Schematic
Courtesy of GENERAL MOTORS CORP.

DIAGNOSTIC INFORMATION AND PROCEDURES

DIAGNOSTIC STARTING POINT - ROOF

Begin the power sunroof system diagnosis with the Diagnostic System Check - Vehicle . The
Diagnostic System Check will provide the following information:

The identification of the control modules which command the system

The ability of the control modules to communicate through the serial data circuit

The identification of any stored DTCs and their status

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the
system and where the procedure is located.

SYMPTOMS - ROOF

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the Sunroof System.
Refer to Checking Aftermarket Accessories .

Inspect the easily accessible or visible system components for obvious damage or conditions
which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to
Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to Power Sunroof Inoperative in order to diagnose the symptom.

POWER SUNROOF INOPERATIVE

Diagnostic Instructions

IMPORTANT: Review the system description in order to familiarize yourself

with the system functions. Refer to Sunroof Description and
Operation.

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Sunroof - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

The power sunroof is operated by the sunroof motor/actuator which consists of the motor and
electronic control unit as a complete assembly. The system is powered by a battery supply circuit
and an ignition/retained accessory power signal circuit determines when the sunroof may be
operated. The switch signal circuits are supplied battery voltage through a resistor and monitored
within the ECU. When a sunroof switch is pressed the switch signal circuit is closed to ground
and most of the voltage supplied to the signal circuit will be dropped across the resistor within
the ECU indicating the switch is active.

Diagnostic Aids

Prior to performing sunroof system circuit diagnosis, perform the Sunroof Motor/Actuator
Initialization/Teach Process (Extended Cab New Motor) or Sunroof Motor/Actuator
Initialization/Teach Process (Extended Cab Existing Motor) or Sunroof Motor/Actuator
Initialization/Teach Process (Crew Cab Existing Motor) or Sunroof Motor/Actuator
Initialization/Teach Process (Crew Cab New Motor).

Reference Information

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

Battery

1

1

-

-

Accessory

1

1

3

-

Close Switch Signal

1

1

1

-

Express Switch Signal

2

2

2

-

Open Switch Signal

1

1

1

-

Vent Close Switch Signal

1

1

1

-

Vent Open Switch Signal

1

1

1

-

Ground

-

1

-

-

1. Power sunroof inoperative
2. Express open and close inoperative
3. Power sunroof operates with ignition off

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Sunroof - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Schematic Reference

Sunroof Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Sunroof Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. With the sunroof in the closed position, press the sunroof open switch. The sunroof should

open.

If the sunroof does not open, refer to Power Sunroof Malfunction below.

2. With the sunroof in the open position, press the sunroof close switch. The sunroof should

close.

If the sunroof does not close, refer to Power Sunroof Malfunction below.

3. With the sunroof in the closed position, operate the sunroof express open feature. The

sunroof should fully open.

If the express open feature does not function, refer to Power Sunroof Express Feature
Malfunction below.

4. With the sunroof in the open position, operate the sunroof express close feature. The sunroof

should fully close.

If the express close feature does not function, refer to Power Sunroof Express Feature
Malfunction below.

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Sunroof - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado