GM Service Manual Online
For 1990-2009 cars only

Diagnostic Aids

The sunroof limit switch can cause the sunroof not to automatically close to the flush close position, with a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. If the circuits test OK, measure the resistance of the Limit Switch. Resistance should be indicated in the sunroof positions mentioned in the Sunroof Description and Operation , otherwise an open should be indicated. An intermittent or poor connection can also cause the sunroof not to operate normally. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Determining if the sunroof is inoperative or is unable to automatically close to the flush close position.

  2. Test for battery voltage (B+) in the supply circuit of the sunroof module. If voltage is not present, go to the RAP Inoperative table.

  3. Test the sunroof limit switch to determine if it is functioning correctly. The sunroof limit switch will close when the sunroof glass reaches the flush closed and comfort stop positions.

Step

Action

Value(s)

Yes

No

Schematic Reference: Sunroof Schematics

Connector End View Reference: Power Roof Systems Connector End Views

DEFINITION: Sunroof may not close automatically to the flush close position, or be inoperative in any slide open position (not vent).

1

Did you perform the Power Sunroof Diagnostic System Check?

--

Go to Step  2

Go to Diagnostic System Check - Power Sunroof

2

Verify that the customer complaint is still present.

Does the sunroof operate OK?

--

Go to Diagnostic Aids

Go to Step 3

3

Does the sunroof slide in any direction?

--

Go to Step 13

Go to Step 4

4

Inspect the RAP fuse for an open.

Is the fuse open?

--

Go to Step 20

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Open the driver door.
  3. Disconnect the sunroof switches harness connector.
  4. Turn ON the ignition, with the engine OFF.
  5. Measure the voltage between the sunroof switch close signal circuit and the sunroof switch low reference circuit of the sunroof slide switch harness connector.

Is the voltage within the specified range?

10-15 V

Go to Step 7

Go to Step 6

6

Measure the voltage between the sunroof switch close signal circuit of the sunroof slide switch harness connector and a good ground.

Is the voltage within the specified range?

10-15 V

Go to Step 19

Go to Step 8

7

Connect a 3-amp fused jumper wire between the sunroof switch close signal circuit and the ground circuit of the sunroof slide switch harness connector.

Does the sunroof close?

--

Go to Step 22

Go to Step 11

8

Measure the voltage between the other sunroof switch signal circuits of the sunroof switch harness connector and a good ground.

Is the voltage within the specified range?

10-15 V

Go to Step 18

Go to Step 9

9

  1. Turn OFF the ignition.
  2. Open the driver door.
  3. Disconnect the sunroof module harness connector.
  4. Turn ON the ignition, with the engine OFF.
  5. Measure the voltage between the battery positive voltage circuit and the ground circuit of the sunroof module harness connector.

Is the voltage within the specified range?

10-15 V

Go to Step 24

Go to Step 10

10

Measure the voltage between the battery positive voltage circuit of the sunroof module harness connector and a good ground.

Is the voltage within the specified range?

10-15 V

Go to Step 26

Go to Retained Accessory Power (RAP) Inoperative in Retained Accessory Power

11

  1. Turn OFF the ignition.
  2. Open the driver door.
  3. Disconnect the sunroof motor harness connector.
  4. Measure the resistance of each sunroof motor control circuit from the sunroof motor harness connector to the sunroof module harness connector.

Is the resistance less than the specified value?

3 ohms

Go to Step 12

Go to Step 27

12

  1. Connect the sunroof switch to the harness connector.
  2. Measure the voltage between the sunroof motor control circuits of the sunroof motor harness connector.
  3. While observing the voltage, press the sunroof slide switch to the close position.

Ignoring polarity, is the voltage within the specified range?

10-15 V

Go to Step 25

Go to Step 23

13

  1. Turn OFF the ignition.
  2. Open the driver door.
  3. Disconnect the limit switch harness connector to the sunroof motor.
  4. Measure the voltage of the sunroof limit switch soft stop signal circuit of the sunroof motor harness connector to a good ground.

Is the voltage within the specified range?

10-15 V

Go to Step 14

Go to Step 16

14

Measure the voltage of the sunroof limit switch soft stop signal circuit and the sunroof limit switch low reference circuit of the sunroof motor harness connector.

Is the voltage within the specified range?

10-15 V

Go to Step 15

Go to Step 17

15

  1. Connect the limit switch connector to the sunroof motor.
  2. Measure the reference voltage between the sunroof limit switch soft stop signal and the sunroof limit switch low reference circuits.
  3. While observing the voltage, press the sunroof slide switch to the close position.

As the sunroof reaches the flush closed position, did the voltage measure near the specified value?

0 V

Go to Step 29

Go to Step 30

16

Test the sunroof limit switch soft stop signal circuit for an open, high resistance or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 24

17

Test the sunroof limit switch low reference circuit for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 24

18

Test the sunroof switch close signal circuit of the sunroof slide switch for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 24

19

Test the sunroof switch low reference circuit of the sunroof slide switch for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 24

20

Test the battery positive voltage circuit of the sunroof module harness connector for a short to ground. Refer to Circuit Testing and Wiring Repairs to in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 21

21

Test the sunroof motor control circuits of the sunroof module for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 25

22

Inspect for a poor connection at the harness connector of the sunroof switches. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 28

23

Test the sunroof limit switch close signal circuit for a short to B+. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 24

24

Inspect for poor connection at the harness connector of the sunroof module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 29

25

Inspect for a poor connection at the harness connector of the sunroof motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

Go to Step 30

26

Repair an open or high resistance in the ground circuit of the sunroof module. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

--

27

Repair an open or high resistance in the sunroof motor control circuits of the sunroof module. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 31

--

28

Replace the sunroof slide switch. Refer to Sunroof Switch Replacement .

Did you complete the replacement?

--

Go to Step 31

--

29

Replace the sunroof module. Refer to Sunroof Control Module Replacement .

Did you complete the replacement?

--

Go to Step 31

--

30

Important: Inspect the sunroof assembly for binding or mechanical failure.

Replace the sunroof motor. Refer to Sunroof Motor/Actuator Replacement .

Did you complete the replacement?

--

Go to Step 31

--

31

  1. Connect any disconnected connectors.
  2. Remove any jumper wires.
  3. Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2