GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • 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

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Ignition

1

1

--

--

Sunroof Limit Switch Soft Stop Signal

3

3

--

--

Sunroof Switch Express Signal

1

2

1

--

Sunroof Switch Open Signal

1

1

1

--

Sunroof Switch Open Vent Signal

1

1

1

--

Sunroof Motor Close Control

1

1

--

--

Sunroof Motor Open Control

1

1

--

--

Sunroof Switch Low Reference

--

1

--

--

Sunroof Limit Switch Low Reference

--

3

--

--

Sunroof Control Module Ground

--

1

--

--

1. Power Sunroof Malfunction

2. Power Sunroof Express Open Feature Malfunction

3. Power Sunroof Can Not Find Closed Position

Circuit/System Description

The sunroof module supplies each of the switch signal circuits with a 12-volt reference. When a switch is pressed the signal circuit is pulled low signaling the sunroof open or close request. The modules determine the motor direction based on inputs received from the sunroof switch. When the module reverses the polarity of the applied voltage, the motor reverses direction.

Reference Information

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 Testing

Important: Because of the accessibility of the sunroof switch, perform the sunroof switch component test before beginning the Circuit/System Testing.

  1. Ignition OFF, disconnect the X2 harness connector at the sunroof control module .
  2. Test for less than 5.0 ohm between the ground circuit terminal D and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal A and ground.
  5. If the test lamp does not illuminate, test the ignition circuit for an open/high resistance. If the circuit tests normal, refer to Retained Accessory Power (RAP) Malfunction .
  6. Ignition OFF, connect the harness connector at the sunroof control module.
  7. Disconnect the harness connector at the sunroof switch.
  8. Test for less than 5.0 ohm between the low reference circuit terminal 5 and ground.
  9. If greater than the specified range, test the low reference circuit for an open/high resistance.
  10. Ignition ON, test for 11.5-12.5 volts between the signal circuits listed below and ground.
  11. • Terminal 2 sunroof open
    • Terminal 3 sunroof vent
    • Terminal 6 sunroof express
    If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the sunroof control module.
  12. Disconnect the X1 harness connector at the sunroof motor.
  13. Connect a test lamp between control circuit terminal A and control circuit terminal B.
  14. Important: Apply ground to the module for no longer than 2 seconds at a time or the module could be damaged.

  15. Momentarily install a 20-amp fused jumper wire between the signal circuit terminal 2 at the sunroof switch harness connector and ground. The test lamp should turn ON.
  16. If the test lamp remains OFF, test for an open/high resistance or short to ground on either control circuit. If the circuit tests normal, replace the sunroof control module.
  17. With the test lamp still connected, connect the sunroof switch.
  18. Press and release the sunroof switch in the positions listed below. The test lamp should turn ON each time a switch is pressed.
  19. • Sunroof express open
    • Sunroof open
    • Sunroof vent
    If the test lamp remains OFF for any of the switch positions, test or replace the sunroof switch.
  20. Ignition OFF, disconnect the X2 harness connector at the sunroof motor.
  21. Test for less than 5.0 ohm between the low reference circuit terminal 3 and ground.
  22. If greater than the specified range, test the low reference circuit for an open/high resistance.
  23. Ignition ON, test for 11.5-12.5 volts between the signal circuit terminal 1 and ground.
  24. If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the sunroof control module.
  25. If all circuits test normal, test or replace the sunroof motor.

Component Testing

Sunroof Switch

  1. Ignition OFF, disconnect the harness connector at the sunroof switch.
  2. Test for infinite resistance between the sunroof switch terminals listed below and the low reference terminal 5 with the switch in the neutral position:
  3. • Roof open terminal 2
    • Roof express terminal 6
    • Roof vent terminal 3
    If less than the specified range, replace the sunroof switch.

    Important: If the switch tests open in any switch position other than Off, test the sunroof switch signal circuits for a short to voltage before replacing the switch.

  4. Test for less than 3 ohms between the sunroof switch terminals listed below and the low reference terminal 5 while pressing the appropriate switch.
  5. • Roof open terminal 2
    • Roof close terminal 2
    • Roof close terminal 3
    • Roof express terminal 6
    • Roof vent open terminal 3
    If greater than the specified range, replace the sunroof switch.

Sunroof Limit Switch

  1. Ignition ON, press the sunroof switch to move the sunroof to the full closed position.
  2. Ignition OFF, disconnect the X2 harness connector at the sunroof motor.
  3. Test for less than 5 ohms between the sunroof motor limit switch terminal 1 and the low reference terminal 3.
  4. If greater than the specified range, replace the sunroof motor.
  5. Ignition ON, press the sunroof switch to move the sunroof to the open or vent position.
  6. Ignition OFF, test for infinite resistance between the sunroof motor limit switch terminal 1 and the low reference terminal 3.
  7. If less than the specified range, replace the sunroof motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Sunroof Switch Replacement
    •  Sunroof Motor/Actuator Replacement
    •  Control Module References for sunroof control module replacement, setup, and programming