GM Service Manual Online
For 1990-2009 cars only

Diagnostic Aids

When testing the sunroof motor open or close control circuits, note the sunroof glass position. If the glass is in the full open or full vent position, any request to operate the glass beyond its limit, may result with no power output to the sunroof motor.

Step

Action

Value(s)

Yes

No

Schematic Reference: Sunroof Schematics

Connector End View Reference: Component Connector End Views

1

Did you review the Power Sunroof Description and Operation and perform the necessary inspections?

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Go to Step 2

Go to Symptoms - Roof

2

Operate the power sunroof.

Does the system operate normally?

--

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Remove the courtesy/reading lamp assembly, that contains the sunroof switch assembly.
  3. Disconnect the sunroof switch harness connector.
  4. Turn ON the ignition.
  5. Measure the voltage from the sunroof switch ignition positive voltage circuit to a good ground, at the sunroof switch harness connector.

Does the voltage measure near the specified value?

B+

Go to Step 4

Go to Step 8

4

Measure the voltage from the sunroof switch ignition positive voltage circuit and the sunroof switch ground circuit, at the sunroof switch assembly harness connector.

Does the voltage measure near the specified value?

B+

Go to Step 5

Go to Step 15

5

  1. Turn OFF the ignition.
  2. Connect the sunroof switch to the harness connector.
  3. Disconnect the sunroof motor harness connector.
  4. Connect a test lamp between the sunroof motor open and close control circuits, at the sunroof motor harness connector, sunroof switch side.
  5. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

--

Go to Step 18

Go to Step 6

6

  1. Observe the sunroof glass position.
  2. Press the sunroof switches to test the sunroof motor control circuits.

Does the test lamp illuminate?

--

Go to Step 14

Go to Step 7

7

Test both sunroof motor open and close control circuits for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 20

Go to Step 13

8

Test the ignition positive voltage circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 20

Go to Step 9

9

  1. Turn OFF the ignition.
  2. Disconnect the P/W relay.
  3. Connect a test lamp between the P/W relay control circuit and a good ground.
  4. Turn ignition ON, with engine OFF.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 17

10

Connect a test lamp between the P/W relay control circuit and the P/W relay ground circuit.

Does the test lamp illuminate?

--

Go to Step 11

Go to Step 17

11

Connect a test lamp between the P/W relay supply voltage circuit and the P/W relay ground circuit.

Does the test lamp illuminate?

--

Go to Step 12

Go to Step 17

12

Inspect for poor connection at the P/W relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 20

Go to Step 16

13

Inspect for poor connections at the sunroof switch assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 20

Go to Step 18

14

Inspect for poor connections at the sunroof motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 20

Go to Step 19

15

Repair an open in the ground circuit between the sunroof switch assembly and the splice. Refer to Wiring Repairs .

Did you complete the repair?

--

Go to Step 20

--

16

Replace the P/W relay.

Did you complete the replacement?

--

Go to Step 20

--

17

Replace the fuse block-instrument panel. Refer to fuse block-instrument panel replacement .

Did you complete the replacement?

--

Go to Step 20

--

18

Replace the courtesy/reading lamp assembly that contains the sunroof switch assembly.

Did you complete the replacement?

--

Go to Step 20

--

19

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

Did you complete the replacement?

--

Go to Step 20

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20

  1. Turn OFF the ignition.
  2. Connect all previously disconnected components.
  3. Replace the POWER fuse, if necessary.
  4. Turn ON the ignition, with the engine OFF.
  5. Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2