GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 CTS 🢒 Body 🢒 Roof 🢒 Power Sunroof Operates Erratically

Diagnostic Aids

If a short to voltage is found on any of the sunroof switch data circuits, the sunroof switch may have an internal short circuit.

Test Description

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

  1. This step tests the sunroof switch data circuits for a short to ground or an open.

    2.

  2. This step tests the sunroof switch data circuits for a short to voltage.

    3.

  3. This step tests the sunroof limit switch low reference circuits of the sunroof motor hall effect sensors for an open.

    4.

  4. This step tests the sunroof obstruction sensor 12-volt reference circuit for a short to ground.

    5.

  5. This step tests the sunroof obstruction sensor 1 signal circuit for a short to ground.

    6.

  6. This step tests the sunroof obstruction sensor 12-volt reference circuit for an open.

    7.

  7. This step tests the sunroof obstruction sensor 1 signal circuit for a short to voltage or an open.

    8.

  8. This step tests the sunroof limit switch soft stop signal circuit for a short to ground.

    9.

  9. This step tests the sunroof obstruction sensor 2 signal circuit for a short to ground, a short to voltage or an open.

    10.

  10. This step tests the sunroof limit switch soft stop signal circuit for an open.

    11.

  11. This step tests the sunroof limit switch low reference circuit of the sunroof motor limit switch for an open.

Step

Action

Values

Yes

No

Schematic Reference: Sunroof Schematics

Connector End View Reference: Power Roof Systems Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Operate the power sunroof through its full range of functions in order to verify that the power sunroof operates erratically fault is present.

Does the power sunroof operate normally?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Open the driver door.
  3. Disconnect the sunroof switch.
  4. Turn ON the ignition, with the engine OFF.
  5. Measure the voltage from each of the sunroof switch data circuits, 1-5, of the sunroof switch harness connector to the sunroof switch low reference circuit of the sunroof switch harness connector.

Do all 5 of the circuit voltages measure near the specified value?

12 V

Go to Step 4

Go to Step 18

4

  1. Turn OFF the ignition.
  2. Open the driver door.
  3. Leave the sunroof switch disconnected.
  4. Disconnect the sunroof control module harness connector C2.
  5. Turn ON the ignition, with the engine OFF.
  6. Measure the voltage from each of the sunroof switch data circuits, 1-6, of the sunroof switch harness connector to a good ground.

Do any of the 6 sunroof switch data circuit voltages measure near the specified value?

12 V

Go to Step 27

Go to Step 5

5

Test the sunroof switch. Refer to Power Sunroof Switch Test .

Is the sunroof switch OK?

--

Go to Step 6

Go to Step 24

6

Is the power sunroof Open/Close function inoperative?

--

Go to Step 7

Go to Step 10

7

  1. Turn OFF the ignition.
  2. Open the driver door.
  3. Connect the sunroof control module harness connector C2.
  4. Disconnect the sunroof motor harness connector C1.
  5. Measure the resistance from the sunroof limit switch low reference circuit of the sunroof motor harness connector C1 to a good ground.

Does the resistance measure less than the specified value?

5 ohms

Go to Step 8

Go to Step 19

8

  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage from the sunroof obstruction sensor 12-volt reference circuit of the sunroof motor harness connector C1 to the sunroof limit switch low reference circuit of the sunroof motor harness connector C1.

Does the voltage measure near the specified value?

12 V

Go to Step 9

Go to Step 20

9

Measure the voltage from the sunroof obstruction sensor 1 signal circuit of the sunroof motor harness connector C1 to the sunroof limit switch low reference circuit of the sunroof motor harness connector C1.

Does the voltage measure near the specified value?

5 V

Go to Step 25

Go to Step 21

10

Does the power sunroof drop down, but not Open?

--

Go to Step 11

Go to Step 13

11

  1. Turn OFF the ignition.
  2. Open the driver door.
  3. Connect the sunroof control module harness connector C2.
  4. Disconnect the sunroof motor harness connector C1.
  5. Turn ON the ignition, with the engine OFF.
  6. Measure the voltage from the sunroof obstruction sensor 12-volt reference circuit of the sunroof motor harness connector C1 to the sunroof limit switch low reference circuit of the sunroof motor harness connector C1.

Does the voltage measure near the specified value?

12 V

Go to Step 12

Go to Step 20

12

Measure the voltage from the sunroof obstruction sensor 1 signal circuit of the sunroof motor harness connector C1 to the sunroof limit switch low reference circuit of the sunroof motor harness connector C1.

Does the voltage measure near the specified value?

5 V

Go to Step 25

Go to Step 21

13

Does the power sunroof only operate to the full Open position?

--

Go to Step 14

Go to Step 16

14

  1. Turn OFF the ignition.
  2. Open the driver door.
  3. Connect the sunroof control module harness connector C2.
  4. Disconnect the sunroof motor harness connector C2.
  5. Turn ON the ignition, with the engine OFF.
  6. Measure the voltage from the sunroof limit switch soft stop signal circuit of the sunroof motor harness connector C2 to a good ground.

Does the voltage measure near the specified value?

12 V

Go to Step 15

Go to Step 22

15

  1. Turn OFF the ignition.
  2. Open the driver door.
  3. Connect the sunroof motor harness connector C2.
  4. Disconnect the sunroof motor harness connector C1.
  5. Turn ON the ignition, with the engine OFF.
  6. Measure the voltage from the sunroof obstruction sensor 2 signal circuit of the sunroof motor harness connector C1 to the sunroof limit switch low reference circuit of the sunroof motor harness connector C1.

Does the voltage measure near the specified value?

5 V

Go to Step 25

Go to Step 23

16

  1. Turn OFF the ignition.
  2. Open the driver door.
  3. Connect the sunroof control module harness connector C2.
  4. Disconnect the sunroof motor harness connector C2.
  5. Turn ON the ignition, with the engine OFF.
  6. Measure the voltage from the sunroof limit switch soft stop signal circuit of the sunroof motor harness connector C2 to a good ground.

Does the voltage measure near the specified value?

12 V

Go to Step 17

Go to Step 22

17

  1. Turn OFF the ignition.
  2. Open the driver door.
  3. Measure the resistance from the sunroof limit switch low reference circuit of the sunroof motor harness connector C2 to a good ground.

Does the resistance measure less than the specified value?

5 ohms

Go to Step 25

Go to Step 24

18

Test the appropriate sunroof switch data circuit of the sunroof switch for a short to ground or an open. 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

19

Test the sunroof limit switch low reference circuit of the sunroof motor for an open. 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

20

Test the sunroof obstruction sensor 12-volt reference circuit of the sunroof motor for a short to ground or an open. 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

21

Test the sunroof obstruction sensor 1 signal circuit of the sunroof motor for the following conditions:

    • A short to ground
    • A short to voltage
    • An open

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

Test the sunroof limit switch soft stop signal circuit of the sunroof motor for a short to ground or an open. 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

23

Test the sunroof obstruction sensor 2 signal circuit of the sunroof motor for the following conditions:

    • A short to ground
    • A short to voltage
    • An open

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

24

Inspect for a poor connection at the harness connector of the sunroof switch. 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

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 29

26

Inspect for poor connection at the harness connector of the sunroof control 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 30

27

Repair the appropriate sunroof switch data circuit of the sunroof switch for a short voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 28

--

28

Replace the sunroof switch. Refer to Sunroof Switch Replacement .

Did you complete the replacement?

--

Go to Step 31

--

29

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

--

30

Replace the sunroof control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 31

--

31

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2