GM Service Manual Online
For 1990-2009 cars only

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Battery Supply

1

1

--

--

Accessory Supply

1

1

2

--

Open Switch Signal

1

1

1

--

Close Switch Signal

1

1

1

--

Switch Ground

--

1

--

--

Motor Ground

--

1

--

--

1. Power Sunroof Inoperative

2. Power Sunroof will operate at all times

Circuit/System Description

The sunroof motor and module assembly is powered by 2 supply circuits, the accessory circuit provides the power for the control module and the battery circuit provides the power to operate the motor. The open and close switch signal circuits are referenced from 12 volts within the control module and are pulled low when an open or close switch is pressed. The sunroof motor is bi-directional and open or close operation is controlled by the polarity of the motor control circuits.

Diagnostic Aids

If voltage is not measured on the sunroof open or close switch signal circuits, the fault could be in the retained accessory power (RAP) supply circuit, battery positive voltage circuit, or sunroof motor ground circuit. If the sunroof motor is not being powered, neither will the sunroof switch signal circuits.

Reference Information

Schematic Reference

Sunroof Schematics

Connector End View Reference

Power Roof Systems Connector End Views

Electrical Information Reference

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

Circuit/System Testing

Sunroof Motor/Actuator

  1. Disconnect the sunroof switch connector.
  2. Test for less than 1.0 ohm of resistance between the switch ground circuit and ground.
  3. If greater than 1.0 ohm test the switch ground circuit for an open/high resistance.
  4. Disconnect the sunroof motor connector and connect the sunroof switch connector.
  5. Test for less than 1.0 ohm of resistance between each of the switch signal circuits and ground while operating the switch in the open and close positions.
  6. If greater than 1.0 ohm in the open or close switch positions test the appropriate switch signal circuit for an open/high resistance. If the signal circuits test normal, replace the sunroof switch.
    If continuity to ground is present on either switch signal circuit while the switch is not in the open or close positions, test the appropriate switch signal circuit for a short to ground. If the signal circuits test normal, replace the sunroof switch.
  7. Verify that a test lamp illuminates between the battery supply circuit and ground.
  8. If the test lamp does not illuminate, repair the battery supply circuit for a short to ground or an open/high resistance.
  9. Ignition ON, verify that a test lamp illuminates between the accessory supply circuit and ground.
  10. If the test lamp does not illuminate, repair the accessory supply circuit for a short to ground or an open/high resistance.
  11. verify that a test lamp illuminates between battery voltage and the ground circuit.
  12. If the test lamp does not illuminate, repair the ground circuit for an open/high resistance.
  13. If all circuits test normal, replace the sunroof motor/actuator.

Component Testing

Power Sunroof Switch

  1. Disconnect the sunroof switch.
  2. Test for less than 1.0 ohm of resistance between each of the switch signal circuit terminals and the ground circuit terminal while operating the switch in the open and close positions.
  3. If greater than 1.0 ohm in the open or close switch positions replace the sunroof switch.
    If continuity present on either switch signal circuit while the switch is not in the open or close positions, replace the sunroof switch.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Sunroof Switch Replacement
    •  Sunroof Motor/Actuator Replacement