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

Battery Positive Voltage

1

1

--

--

Sunroof Module Ground

--

1

--

--

Sunroof Enable Signal

1

1

--

--

Sunroof Switch Close Signal

1

1

1

--

Sunroof Switch Close Vent Signal

1

1

1

--

Sunroof Switch Express Signal

1

2

1

--

Sunroof Switch Express Vent Signal

1

2

1

--

Sunroof Switch Ground

--

1

--

--

Sunroof Switch Open Signal

1

1

1

--

Sunroof Switch Open Vent Signal

1

1

1

--

1. Power sunroof inoperative

2. Power sunroof express feature inoperative

Circuit/System Description

The sunroof module determines the sunroof motor direction based on inputs received from the overhead console sunroof switches. The module supplies each of the sunroof switch signal circuits with a 5-volt reference. When the switch is pressed the signal circuit is pulled low signaling the roof open or closed request. When the ignition switch is in the ON position or when retained accessory power (RAP) is active, voltage is applied to the sunroof module via the LIFTGATE/SUNROOF fuse. The sunroof module controls the sunroof motor direction by changing the polarity of the applied voltage. The sunroof module remembers the sunroof position whenever the ignition switch is turned to the OFF position.

Diagnostic Aids

A short to B+ on any of the sunroof switch signal circuits will open the ground trace in the sunroof switch.

Reference Information

Schematic Reference

Sunroof Schematics

Connector End View Reference

Sunroof Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Circuit/System Testing

Power Sunroof Inoperative

  1. Ignition OFF, disconnect the harness connector at the sunroof switch.
  2. Interior lamps OFF, Test for less than 10.0 ohms of resistance between the ground circuit terminal 5 and ground.
  3. If greater than 10.0 ohms, test the ground circuit for an open/high resistance.
  4. Connect a 3A fused jumper wire between the following sunroof switch signal circuits and ground. The roof should be inoperative in at least one or more directions.
  5. • Terminal 8 sunroof switch open signal
    • Terminal 2 sunroof switch close signal
    • Terminal 4 sunroof switch open vent signal
    • Terminal 6 sunroof switch close vent signal
    If the roof moved in all directions, replace the sunroof switch.
  6. Disconnect the harness connector at the sunroof control module.
  7. Test for less than 1.0 ohm of resistance between the ground circuit terminal 4 and ground.
  8. If greater than 1.0 ohm, test the ground circuit for an open/high resistance.
  9. Test for less than 1.0 ohm of resistance between the ground circuit terminal 14 and ground.
  10. If greater than 1.0 ohm, test the ground circuit for an open/high resistance.
  11. Ignition ON, verify that a test lamp illuminates between the battery positive voltage circuit terminal 1 and ground.
  12. If the test lamp does not illuminate, test the battery positive voltage circuit for a short to ground or an open/high resistance
  13. Ignition ON, verify that a test lamp illuminates between the signal circuit terminal 2 and ground.
  14. If the test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance
  15. Ignition OFF, connect the harness connector at the sunroof motor/actuator assembly.
  16. Ignition ON, test for 4.8-5.2 volts between the following sunroof switch signal circuits and ground.
  17. • Terminal 1 sunroof express vent signal
    • Terminal 2 sunroof switch close signal
    • Terminal 4 sunroof switch open vent signal
    • Terminal 6 sunroof switch close vent signal
    • Terminal 7 sunroof express signal
    • Terminal 8 sunroof switch open signal
    If less than 4.8 volts, test the appropriate signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the sunroof motor/actuator assembly.
    If greater than 5.2 volts, test the appropriate signal circuit for a short to voltage. If the circuit tests normal, replace the sunroof motor/actuator assembly.
  18. Ignition OFF, connect the harness connector at the sunroof switch.
  19. If all circuits test normal, test or replace the sunroof motor/actuator assembly.

Power Sunroof Express Feature Inoperative

  1. Ignition OFF, disconnect the harness connector at the sunroof switch.
  2. Ignition ON, with the sunroof in the closed position, connect a 3A fused jumper wire between the sunroof switch open signal circuit terminal 8 and the sunroof express signal circuit terminal 7 to ground for less than 1 second. The roof should express open.
  3. If the roof did not express open, test the express signal circuit for a short to voltage or an open high resistance. If the circuit tests normal, replace the sunroof motor/actuator assembly.
  4. Ignition ON, with the sunroof in the closed position, connect a 3A fused jumper wire between the sunroof switch vent open signal circuit terminal 4 and the sunroof express vent signal circuit terminal 1 to ground for less than 1 second. The roof should express vent open.
  5. If the roof did not express vent open, test the express signal circuit for a short to voltage or an open high resistance. If the circuit tests normal, replace the sunroof motor/actuator assembly.
  6. If all circuits test normal, test or 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 following sunroof switch terminals with the switch in the open position:
  3. • Switch ground terminal 5 and roof open terminal 8
    • Switch ground terminal 5 and roof express terminal 7
    • Switch ground terminal 5 and roof close terminal 2
    • Switch ground terminal 5 and vent open terminal 4
    • Switch ground terminal 5 and vent express terminal 1
    • Switch ground terminal 5 and vent close terminal 6
    If less than infinite for any test, 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 of resistance between the following sunroof switch terminals while pressing the appropriate switch.
  5. • Switch ground terminal 5 and roof open terminal 8
    • Switch ground terminal 5 and roof express terminal 7
    • Switch ground terminal 5 and roof close terminal 2
    • Switch ground terminal 5 and vent open terminal 4
    • Switch ground terminal 5 and vent express terminal 1
    • Switch ground terminal 5 and vent close terminal 6
    If greater than 3 ohms on any of the tests, replace the sunroof switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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