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

1

--

--

Ignition

1

1

2

--

Signal Terminal 5

1

1

1*

--

Signal Terminal 4

1

1

1*

--

Signal Terminal 3

1

1

1*

--

Signal Terminal 2

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 operates with ignition OFF

Circuit/System Description

The sunroof control module determines the sunroof motor direction based on the inputs received from the sunroof switch. The sunroof switch is a rotary dial type switch with four outputs, the sunroof switch data 1 through 4 signal circuits. The coded inputs to the sunroof control module will initiate a request to slide the sunroof window to a specific position. The sunroof control module supplies the corresponding switch data signal circuits with a 12-volt reference. When the ignition switch is in the ON position, voltage is applied to the sunroof control module via the electronic control unit and the S/ROOF 20A fuse located in the instrument panel fuse block.

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

Circuit/System Verification

  1. With the sunroof in the closed position, turn the rotary dial switch clockwise through each of the open slide positions. It should open in increments to the fully open position. When the rotary dial switch is brought back to the close position the sunroof should express close.
  2. With the sunroof in the closed position, turn the rotary dial switch counter clockwise through each of the vent positions. It should vent open in increments to the fully vent open position. When the rotary dial switch is brought back to the close position the sunroof should express close.

Circuit/System Testing

Note: Portions of the circuit/system testing require removal of the headliner. It is suggested that the sunroof switch component test is performed prior to removing the headliner.

  1. Ignition OFF, disconnect the harness connector at the sunroof control module.
  2. Ignition OFF, test for less than 5 Ω between the ground circuit terminal 10 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 6 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, replace the sunroof control module.
  6. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 9 and ground.
  7. 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 sunroof control module.
  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 Ω between the ground circuit terminal 1 and ground.
  11. If greater than the specified range, test the ground circuit for an open/high resistance.
  12. Ignition ON, test for B+ between the signal circuit terminal 2 and ground.
  13. If less than the specified value, test for a short to ground or an open/high resistance. If the circuit tests normal, replace the sunroof control module.
  14. Ignition ON, test for B+ between the signal circuit terminal 3 and ground.
  15. If less than the specified value, test for a short to ground or an open/high resistance. If the circuit tests normal, replace the sunroof control module.
  16. Ignition ON, test for B+ between the signal circuit terminal 5 and ground.
  17. If less than the specified value, test for a short to ground or an open/high resistance. If the circuit tests normal, replace the sunroof control module.
  18. Ignition ON, test for B+ between the signal circuit terminal 6 and ground.
  19. If less than the specified value, test for a short to ground or an open/high resistance. If the circuit tests normal, replace the sunroof control module.
  20. 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 continuity between the terminals indicated for each position of the switch. The continuity should display as indicated in the test table.
  3. If not the specified value for all switch positions, test the appropriate signal circuit for a short to battery voltage. If all circuits test normal, replace the sunroof switch.

Switch Position

Terminal 1 & Terminal 2

Terminal 1 & Terminal 3

terminal 1 & Terminal 5

Terminal 1 & Terminal 6

Vent Position 3

0-200 Ω

Infinite

Infinite

Infinite

Vent Position 2

Infinite

0-200 Ω

Infinite

Infinite

Vent Position 1

0-200 Ω

0-200 Ω

Infinite

Infinite

Close

0-200 Ω

0-200 Ω

Infinite

0-200 Ω

Roof Position 1

Infinite

0-200 Ω

Infinite

0-200 Ω

Roof Position 2

Infinite

Infinite

Infinite

0-200 Ω

Roof Position 3

0-200 Ω

Infinite

Infinite

0-200 Ω

Roof Position 4

0-200 Ω

Infinite

0-200 Ω

0-200 Ω

Roof Position 5

Infinite

Infinite

0-200 Ω

0-200 Ω

Roof Position 6

Infinite

0-200 Ω

0-200 Ω

0-200 Ω

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