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, 2

1, 2

--

--

Sunroof Control Module Ignition

1, 2

1, 2

--

--

Relay K50 Ignition

1

1

--

--

Sunroof Switch Close Signal

1

1

1

--

Sunroof Switch Open Signal

1

1

1

--

Sunshade Switch Close Signal

2

2

2

--

Sunshade Switch Open Signal

2

2

2

--

Sunroof Switch Ground

--

1

--

--

Sunshade Switch Ground

--

2

--

--

Sunroof Control Module Ground

--

1

--

--

Sunshade Control Module Ground

--

2

--

--

Relay K50 Ground

--

1

--

--

1. Power Sunroof Malfunction

2. Power Sunshade Malfunction

Circuit/System Description

The sunroof and sunshade control modules supply 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 or sunshade open or close request. The modules determine the motor direction based on inputs received from the overhead console sunroof switches. When the modules reverse the polarity of the applied voltage, the motors reverse direction. Ignition voltage is supplied to the sunroof and sunshade modules. B+ is applied to the sunroof and sunshade control modules via the SUNROOF fuse.

Diagnostic Aids

A short to B+ on any of the sunroof or sunshade switch signal circuits may open the ground circuit in the switch.

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 sunshade in the closed position, press the sunshade open switch for 2 seconds. The sunshade should express open.
  2. If the sunshade does not move, refer to Power Sunshade Malfunction.
    If the sunshade does not express open, refer to Power Sunroof/Sunshade Express Feature Malfunction.
  3. With the sunshade in the open position, press the sunshade close switch. The sunshade should close.
  4. If the sunshade does not move, refer to Power Sunshade Malfunction.
  5. With the sunshade in the open position and the sunroof in the closed position, press the sunroof 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 vent position, press the sunroof open switch for 2 seconds. The sunroof should express open.
  8. If the sunroof does not move, refer to Power Sunroof Malfunction.
    If the sunroof does not express open, refer to Power Sunroof/Sunshade Express Feature Malfunction.
  9. With the sunroof in the open position, press the sunroof close switch. The sunroof should close.
  10. If the sunroof does not close, refer to Power Sunroof Will Not Close.

Circuit/System Testing

Important: Because of the accessibility of the sunroof switch, perform the sunroof/sunshade 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 ohms between the ground circuit terminal 6 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.
  5. 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, determine if the sunroof or sunshade control module is causing the fuse to open. Replace the appropriate module.
  6. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 4 and ground.
  7. If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.
  8. Ignition OFF, connect the harness connector at the sunroof control module.
  9. Disconnect the harness connector at the sunroof switch.
  10. Test for less than 5.0 ohms between the ground circuit terminal 4 and ground.
  11. 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 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.

  12. Ignition ON, momentarily install a 10-amp fused jumper wire between the signal circuit terminal 5 and ground. The sunroof should move.
  13. 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.
  14. Momentarily install a 10-amp fused jumper wire between the signal circuit terminal 2 and ground. The sunroof should move.
  15. 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.
  16. If all circuits test normal, test or replace the sunroof switch.

Power Sunshade Malfunction

  1. Ignition OFF, disconnect the harness connector at the sunshade control module.
  2. Test for less than 5.0 ohms between the ground circuit terminal 6 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.
  5. 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, determine if the sunroof or sunshade control module is causing the fuse to open. Replace the appropriate module.
  6. Ignition ON, test for 10 - 12.5 volts between the serial data circuit terminal 3 and ground.
  7. If less than the specified range, test the serial data circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the sunroof control module.
    If greater than the specified range, test the serial data circuit for a short to voltage. If the circuit tests normal, replace the sunroof control module.
  8. Ignition OFF, connect the harness connector at the sunshade control module.
  9. Disconnect the harness connector at the sunshade switch.
  10. Test for less than 5.0 ohms between the ground circuit terminal 4 and ground.
  11. 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.

  12. Momentarily install a 10-amp fused jumper wire between the signal circuit terminal 5 and ground. The sunshade should move.
  13. If the sunshade 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 sunshade control module.
  14. Momentarily install a 10-amp fused jumper wire between the signal circuit terminal 2 and ground. The sunshade should move.
  15. If the sunshade 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 sunshade control module.
  16. If all circuits test normal, test or replace the sunshade switch.

Power Sunroof Will Not Close

  1. Ignition OFF, disconnect the sunroof switch.
  2. Ignition ON, test for less than 11 volts between the signal circuit terminal 2 and ground.
  3. If greater than the specified range, test or replace the sunroof switch.
  4. Ignition OFF, disconnect the K50 relay.
  5. Test for less than 5 ohms between the ground circuit terminal 3 and ground.
  6. If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Ignition ON, test for greater than 11.5 volts between the ignition circuit terminal 2 and ground.
  8. If less than the specified range, test the ignition circuit for an open/high resistance or short to ground.
  9. Test for greater than 11.5 volts between the ignition circuit terminal 4 and ground.
  10. If less than the specified range, test the ignition circuit for an open/high resistance or short to ground.
  11. Connect a 10-amp fused jumper wire between the ignition circuit terminal 1 and the control circuit terminal 4.
  12. Disconnect the sunroof switch. Test for greater than 11.5 volts between the signal circuit terminal 2 and ground.
  13. If less than the specified range, test the signal circuit for an open/high resistance or short to ground.
  14. If all circuits test normal, replace the K50 relay.

Power Sunroof/Sunshade Express Feature Malfunction

  1. Perform the Sunroof Front Sunshade/Window Initialization procedure.
  2. With the sunshade in the closed position, press the sunshade open switch for 2 seconds. The sunshade should express open.
  3. If the sunshade does not express open, replace the sunshade control module.
  4. With the sunroof in the vent position, press the sunroof open switch for 2 seconds. The sunroof should express open.
  5. If the sunroof does not express open, replace the sunroof control module.

Component Testing

Sunroof/Sunshade Switch

  1. With the 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 4 with the switch in the open position.
  3. • Roof open terminal 5
    • Roof close terminal 2
    If not the specified value, 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 5.0 ohms between the switch terminals listed below and the ground terminal 4 with the switch in the appropriate position.
  5. • Roof open terminal 5
    • Roof 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.

    •  Headlining Trim Panel Replacement
    •  Control Module References for sunroof control module, or sunroof shade control module replacement, setup, and programming