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

B+

1

1

--

--

Ignition

1

1

3

--

Sunroof Switch Express Signal

1

2

1*

--

Sunroof Switch Open Signal

1

1

1*

--

Sunroof Switch Open Vent Signal

1

1

1*

--

Sunroof Switch Low Reference

--

1

--

--

Sunroof Control Module Ground

--

1

--

--

* Internal damage to the sunroof switch may occur if shorted to B+

1. Power sunroof malfunction

2. Power sunroof express open feature malfunction

3. Power sunroof operates with ignition OFF

Circuit/System Description

The sunroof control module determines the sunroof motor direction based on inputs received from the sunroof switch. The sunroof control module supplies each of the sunroof switch signal circuits with a 12 V reference. When the switch is pressed the signal circuit is pulled low signaling the roof open or close request. When the ignition switch is in the ON position or when retained accessory power (RAP) is active, voltage is applied to the sunroof control module via the RAP relay and the SUNROOF fuse. The sunroof control module controls the sunroof motor direction by changing the polarity of the applied voltage.

Diagnostic Aids

If the sunroof is experiencing an intermittent inoperative condition, check the sunroof switch ground circuit for an open. If the sunroof switch ground circuit is open, the switch may take a redundant path to ground through the switch illumination circuit. When the lights are turned ON, the redundant path to ground is removed, and the sunroof will become inoperative.

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 Verification

  1. With the sunroof in the closed position, press the sunroof open switch. The sunroof should open.
  2. If the sunroof does not open, refer to Power Sunroof Malfunction.
  3. With the sunroof in the open position, press the sunroof close switch. The sunroof should close.
  4. If the sunroof does not close, refer to Power Sunroof Malfunction.
  5. With the sunroof in the closed position, press the sunroof vent open switch. The sunroof should open to the vent position.
  6. If the sunroof does not open to the vent position, refer to Power Sunroof Malfunction.
  7. With the sunroof in the closed position, momentarily press the sunroof open switch to the second detente. The sunroof should express open.
  8. If the sunroof does not express open, refer to Power Sunroof Express Feature Malfunction.

Circuit/System Testing

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

Power Sunroof Malfunction

  1. Ignition OFF, disconnect the harness connector at the sunroof control module.
  2. Test for less than 5.0 Ω between the ground circuit terminal 3 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Test for less than 5.0 Ω between the ground circuit terminal 12 and ground.
  5. If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Test for less than 5.0 Ω between the ground circuit terminal 13 and ground.
  7. If greater than the specified range, test the ground circuit for an open/high resistance.
  8. Verify that a test lamp illuminates between the B+ circuit terminal 1 and ground.
  9. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, replace the sunroof control module.
  10. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 2 and ground.
  11. 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 Retained Accessory Power Malfunction.
  12. Ignition OFF, connect the harness connector at the sunroof control module.
  13. Disconnect the harness connector at the sunroof switch.
  14. Test for less than 5.0 Ω between the low reference circuit terminal 3 and ground.
  15. If greater than the specified range, test the low reference circuit for an open/high resistance.
  16. Ignition ON, at the sunroof switch harness connector, test for B+ between the signal circuit terminal 1 and ground.
  17. 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 control module.
  18. Test for B+ between the signal circuit terminal 2 and ground.
  19. 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 control module.
  20. Test for B+ between the signal circuit terminal 4 and ground.
  21. 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 control module.
  22. If all circuits test normal, test or replace the sunroof switch.

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 3 A fused jumper wires between both signal circuits listed below and ground for less than 1 second. The sunroof should express open.
  3. • Terminal 1
    • Terminal 4
    If the sunroof did not express open, test the signal circuit terminal 4 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the sunroof control module.
  4. If all circuits test normal, test or replace the sunroof switch.

Component Testing

  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 3 with the switch in the neutral position:
  3. • Roof open terminal 1
    • Roof express terminal 4
    • Roof vent terminal 2
    If less than the specified range, replace the sunroof switch.

    Note: 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 Ω between the sunroof switch terminals listed below and the low reference terminal 3 while pressing the appropriate switch.
  5. • Roof open terminal 1
    • Roof close terminal 1
    • Roof express terminal 4
    • Roof vent open terminal 2
    • Roof vent close terminal 2
    If greater than the specified range, replace the sunroof switch.

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