GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 STS 🢒 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

B+

1

1

--

--

Sunroof Enable Signal

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*

--

Ground - Sunroof Switch

--

1

--

--

Ground - Sunroof Motor/Actuator

--

1

--

--

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

1. Power sunroof malfunction

2. Power sunroof express feature malfunction

3. Sunroof operates with ignition OFF

Circuit/System Description

The sunroof control module supplies each of the sunroof 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 module determines 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. A sunroof enable signal is supplied to the sunroof control module by the rear integration module (RIM). B+ is applied to the sunroof control module via the S/ROOF fuse.

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 have taken an alternate path to ground through the switch illumination circuit. When the lights are turned On, the alternate path to ground is removed, and the sunroof will become inoperative.
    • A short to B+ on any of the sunroof switch signal circuits will open the ground circuit in the sunroof 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. Verify that the RAP is functioning normally.
    2. ⇒If the RAP is not functioning normally refer to Retained Accessory Power Malfunction.
  2. With the sunroof in the closed position, press the sunroof open switch. The sunroof should open.
    3. ⇒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.
  4. With the sunroof in the closed position, operate the sunroof express open feature. The sunroof should fully open.
    5. ⇒If the express open feature does not function, 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. Verify that a test lamp illuminates between the B+ circuit terminal 1 and ground.
    4. ⇒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.
  4. Ignition ON, verify that a test lamp illuminates between the signal circuit terminal 2 and B+.
    5. ⇒If the test lamp does not illuminate, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
  5. Ignition OFF, connect the harness connector at the sunroof control module.
  6. Disconnect the harness connector at the sunroof switch.
  7. Interior lamps OFF, test for less than 10.0 ohm between the ground circuit terminal 5 and ground.
    8. ⇒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.

  8. Ignition ON, momentarily install a 10-amp fused jumper wire between the signal circuit terminal 8 and ground. The sunroof should move.
    9. ⇒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.
  9. Momentarily install a 10-amp fused jumper wire between the signal circuit terminal 2 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. 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.
    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. Momentarily install a 10-amp fused jumper wire between the signal circuit terminal 6 and ground. The sunroof should close.
    12. ⇒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.
  12. 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 7
    • Terminal 8
    ⇒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 3 A 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 1
    • Terminal 4
    ⇒If the roof did not express open to the vent position, test the signal circuit terminal 1 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 sunroof switch terminals listed below and the ground circuit terminal 5 with the switch in the open position.
    3. • Vent express terminal 1
    • Sunroof close terminal 2
    • Vent open terminal 4
    • Vent close terminal 6
    • Sunroof express terminal 7
    • Sunroof 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 ohm between the sunroof switch terminals listed below and the ground circuit terminal 5 and with the switch in the appropriate position.
    4. • Vent express terminal 1
    • Sunroof close terminal 2
    • Vent open terminal 4
    • Vent close terminal 6
    • Sunroof express terminal 7
    • Sunroof 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
    •  Control Module References for sunroof motor/actuator replacement, setup, and programming