Chevrolet Silverado / GMC Sierra. Manual — part 2771

Circuit/System Testing

Power Sunroof Malfunction

1. Disconnect the sunroof switch connector.

2. Verify that a test lamp illuminates between the ground circuit terminal 5 and B+.

If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Ignition ON, connect a 3A fused jumper wire between the signal circuit listed below and

ground. The sunroof should be inoperative in at least one or more directions.

Sunroof open terminal 6

Sunroof close terminal 4

Vent open (Crew Cab) terminal 2

Vent close (Crew Cab) terminal 8

If the sunroof moved in all directions, replace the sunroof switch.

4. Ignition OFF, disconnect the harness connector at the sunroof motor/actuator.

5. Verify that a test lamp illuminates between the ground circuit terminal 1 and B+.

If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

6. Verify that a test lamp illuminates between the B+ circuit terminal 6 and ground.

If the test lamp does not illuminate, test the B+ circuit for a short to ground or an
open/high resistance.

7. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 3 and

ground.

If the test lamp does not illuminate, test the ignition circuit for a short to ground or an
open/high resistance. If the circuit tests normal, refer to Power Mode Mismatch .

8. Ignition OFF, connect the sunroof motor/actuator harness connector.

9. Ignition ON, at the sunroof switch harness connector, test for 8.5-12.8 volts between the

signal circuits listed below and ground.

Sunroof open terminal 6

Sunroof close terminal 4

Vent open (Crew Cab) terminal 2

Vent close (Crew Cab) terminal 8

If less than the specified value, test the signal circuit for a short to ground or an
open/high resistance. If the circuit tests normal, replace the sunroof motor/actuator.

10. If all circuits test normal, replace the sunroof motor/actuator.

2008 Chevrolet Silverado 1500

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

Crew Cab Power Sunroof Express Feature Malfunction

1. Ignition OFF, disconnect the harness connector at the sunroof switch.

2. Ignition ON, with the sunroof in the closed position, connect 3A fused jumper wires

between both signal circuits listed below and ground for less than 1 second. The sunroof
should express open.

Terminal 1

Terminal 6

If the sunroof did not express open, test the signal circuit terminal 1 for a short to
ground or an open/high resistance. If the circuit tests normal, replace the sunroof
motor/actuator.

3. With the sunroof in the open position, connect 3A fused jumper wires between both signal

circuits listed below and ground for less than 1 second. The sunroof should express open.

Terminal 1

Terminal 4

If the sunroof did not express open, test the signal circuit terminal 1 for a short to
ground or an open/high resistance. If the circuit tests normal, replace the sunroof
motor/actuator.

4. If all circuits test normal, replace the sunroof switch.

Component Testing

Sunroof Switch

1. Ignition OFF, disconnect the harness connector at the sunroof switch.

2. Test for infinite resistance between the switch terminals listed below and the ground circuit

terminal 5 with the switch in the open position.

Express open/close (Crew Cab) terminal 1

Sunroof close terminal 4

Sunroof open terminal 6

Vent close (Crew Cab) terminal 8

Vent open (Crew Cab) terminal 2

If not the specified value, replace the sunroof switch.

3. Test for less than 5 ohms between the switch terminals listed below and the ground circuit

terminal 5 with the switch in the closed position.

Express open/close (Crew Cab) terminal 1

2008 Chevrolet Silverado 1500

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

Sunroof close terminal 4

Sunroof open terminal 6

Vent close (Crew Cab) terminal 8

Vent open (Crew Cab) terminal 2

If greater than the specified value, replace the sunroof switch.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Sunroof Motor/Actuator Replacement (Extended Cab) or Sunroof Motor/Actuator
Replacement (Crew Cab)

Sunroof Switch Replacement (Crew Cab)

REPAIR INSTRUCTIONS

SUNROOF AIR DEFLECTOR REPLACEMENT (EXTENDED CAB)

Removal Procedure

2008 Chevrolet Silverado 1500

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

Fig. 2: Actuator Blocks
Courtesy of GENERAL MOTORS CORP.

1. Open the power sunroof window to the fully rear position.

2. Remove the actuators screws (1) and actuators (2) from each side of the sunroof module.

2008 Chevrolet Silverado 1500

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