GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2009 🢒 Lucerne 🢒 Roof 🢒 Sunroof 🢒 Power Sunroof Malfunction

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 Terminal 1

1

1

--

--

Ignition Terminal 3

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 Open Signal

1

1

1*

--

Sunroof Switch Open Vent Signal

1

1

1*

--

Sunroof Switch Ground

--

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 feature malfunction

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-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 motor via the RAP relay, the SUN ROOF fuse, and the RAP2 fuse. The sunroof control module controls the 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.
  2. With the sunroof in the open position, press the sunroof close switch. The sunroof should close.
    3. ⇒If the sunroof does not close, refer to Power Sunroof Malfunction.
  3. With the sunroof in the closed position, press the sunroof vent open switch. The sunroof should open to the vent position.
    4. ⇒If the sunroof does not open to the vent position, refer to Power Sunroof Malfunction.
  4. With the sunroof in the vent open position, press the sunroof vent close switch. The sunroof should close.
    5. ⇒If the sunroof does not close, refer to Power Sunroof Malfunction.
  5. With the sunroof in the closed position, momentarily press the sunroof open switch to the second detente. The sunroof should express open.
    6. ⇒If the sunroof does not express open, refer to Power Sunroof Express Feature Malfunction.

Circuit/System Testing

Important: 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 ohm between the ground circuit terminal 4 and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Test for less than 5.0 ohm between the ground circuit terminal 13 and ground.
    4. ⇒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 1 and ground.
    5. ⇒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 and the ignition circuit fuse is open, replace the fuse and replace the sunroof control module.
  5. Verify that a test lamp illuminates between the ignition circuit terminal 3 and ground.
    6. ⇒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 and the ignition circuit fuse is open, replace the fuse and replace the sunroof control module.
  6. Ignition OFF, connect the harness connector at the sunroof control module.
  7. Disconnect the harness connector at the sunroof switch.
  8. Interior lamps OFF, test for less than 10.0 ohm between the ground circuit terminal 5 and ground.
    9. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.

    Important: Apply ground to the module for no longer than 2 seconds at a time or the module could be damaged.

    When performing the following tests, make sure that the sunroof or sunshade is not at its end of travel position by switching the grounded jumper to the other signal circuit if the sunroof or sunshade did not move in one direction.

  9. Ignition ON, momentarily install a 10-amp fused jumper wire between the signal circuit terminal 8 and ground. The sunroof should move.
    10. ⇒If the sunroof does not move, test the signal circuit for a short to ground, short to voltage or an open/high resistance. If the circuit test is normal, replace the sunroof control module.
  10. Momentarily install a 10-amp fused jumper wire between the signal circuit terminal 2 and ground. The sunroof should move.
    11. ⇒If the sunroof does not move, test the signal circuit for a short to ground, short to voltage or an open/high resistance. If the circuit test is normal, replace the sunroof control module.
  11. With the sunroof in the fully closed position, momentarily install a 10-amp fused jumper wire between the signal circuit terminal 4 and ground. The sunroof should vent open.
    12. ⇒If the sunroof does not move, test the signal circuit for a short to ground, short to voltage or an open/high resistance. If the circuit test is normal, replace the sunroof control module.
  12. Momentarily install a 10-amp fused jumper wire between the signal circuit terminal 6 and ground. The sunroof should close.
    13. ⇒If the sunroof does not close, test the signal circuit for a short to ground, short to voltage or an open/high resistance. If the circuit test is normal, replace the sunroof control module.
  13. 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 3A fused jumper wires between both signal circuits listed below and ground for less than 1 second. The sunroof should express open.
    3. • Terminal 7
    • Terminal 5
    ⇒If the sunroof did not express open, test the signal circuit terminal 7 for a short to voltage or an open high resistance. If the circuit tests normal, replace the sunroof control module.
  3. 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 roof should express open to the vent position.
    4. • Terminal 10
    • Terminal 8
    ⇒If the roof did not express open to the vent position, test the signal circuit terminal 10 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

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 terminal 5 with the switch in the open position.
    3. • Vent express terminal 1
    • Roof close terminal 2
    • Vent open terminal 4
    • Vent close terminal 6
    • Roof express terminal 7
    • Roof open terminal 8
    ⇒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.

  3. Test for less than 3 ohms between the switch terminals listed below and the ground terminal 5 while pressing the appropriate switch.
    4. • Vent express terminal 1
    • Roof close terminal 2
    • Vent open terminal 4
    • Vent close terminal 6
    • Roof express terminal 7
    • Roof open terminal 8
    ⇒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 motor replacement, setup, and programming