GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Schematic Reference: Inside Rearview Mirror Schematics

Connector End View Reference: Window Systems Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn ON the ignition switch, with the engine OFF.
  2. Activate the inside rear mirror automatic Day-Night feature.
  3. Cover the sensor on the mirror back, facing the front window.
  4. Shine a bright light into the sensor on the mirror face, facing the rear window.

Does the inside rearview mirror darken?

--

Go to Step 3

Go to Automatic Day-Night Mirrors Inoperative

3

While shining a bright light into the sensor on the mirror face, facing the rear window, observe the driver outside rearview mirror.

Does the driver outside rearview mirror darken?

--

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 4

4

  1. Turn OFF the ignition switch.
  2. Disconnect the C3 harness connector at the driver door module (DDM).
  3. Turn ON the ignition switch, with the engine OFF.
  4. Activate the inside rear mirror automatic Day-Night feature.
  5. Cover the sensor on the mirror back, facing the front window.
  6. Shine a bright light into the sensor on the mirror face, facing the rear window.
  7. Measure the voltage between the automatic day/night mirror signal circuit and the automatic day/night mirror low reference circuit at the DDM C3 harness connector.

Is the measured voltage within the specified value?

0.75-1.5 V

Go to Step 7

Go to Step 5

5

Is the voltage greater than the specified value?

1.5 V

Go to Step 18

Go to Step 6

6

Measure the voltage between the automatic day/night mirror signal circuit of the driver outside mirror element and ground.

Is the voltage within the specified range?

0.75-1.5 V

Go to Step 13

Go to Step 12

7

  1. Turn OFF the ignition switch.
  2. Reconnect the C3 harness connector at the DDM.
  3. Carefully disconnect the driver outside rearview mirror face. Refer to Outside Rearview Mirror Glass Replacement .
  4. Turn ON the ignition switch, with the engine OFF.
  5. Activate the inside rear mirror automatic Day-Night feature.
  6. Cover the sensor on the mirror back, facing the front window.
  7. Shine a bright light into the sensor on the mirror face, facing the rear window.
  8. Measure the voltage between the automatic day/night mirror signal circuit and the automatic day/night mirror low reference circuit at the driver outside rearview mirror element.

Is the measured voltage within the specified range?

0.75-1.5 V

Go to Step 14

Go to Step 8

8

Is the voltage greater than the specified value?

1.5 V

Go to Step 18

Go to Step 9

9

  1. Turn OFF the ignition switch.
  2. Disconnect the C3 harness connector at the driver door module (DDM).
  3. Measure the resistance of the automatic day/night mirror signal circuit of the driver outside rearview mirror element between the driver outside rearview mirror element and the DDM.

Does the resistance measure less than the specified value?

3 Ω

Go to Step 10

Go to Step 15

10

Measure the resistance between the automatic day/night mirror signal circuit of the driver outside mirror element and good ground.

Is the measured voltage within the specified value?

OL

Go to Step 11

Go to Step 15

11

Measure the resistance of the automatic day/night mirror low reference circuit of the driver outside rearview mirror element between the driver outside rearview mirror element and the DDM.

Is the resistance less than the specified value?

3 Ω

Go to Step 17

Go to Step 15

12

Test the automatic day/night mirror signal circuit of the driver outside rearview mirror element for an open, high resistance, or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find or correct the condition?

--

Go to Step 23

Go to Step 16

13

Test the automatic day/night mirror low reference circuit of the driver outside rearview mirror element for an open, high resistance, or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find or correct the condition?

--

Go to Step 23

Go to Step 16

14

Check for poor connections at the harness connector of the driver outside rearview mirror face. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find or correct the condition?

--

Go to Step 23

Go to Step 19

15

Check for poor connections at the harness connector of the driver outside mirror face. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find or correct the condition?

--

Go to Step 23

Go to Step 20

16

Check for poor connections at the harness connector of the Inside rearview mirror. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find or correct the condition?

--

Go to Step 23

Go to Step 21

17

Check for poor connections at the harness connector of the DDM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find or correct the condition?

--

Go to Step 23

Go to Step 22

18

Important:: A short to voltage in the signal circuit of the driver outside rearview mirror element will cause permanent damage to both the driver outside rearview mirror element and the inside rearview mirror.

Locate and repair a short to voltage in the automatic day/night mirror signal circuit of the driver outside rearview mirror element. Refer to Wiring Repairs .

Did you complete the repair?

--

Go to Step 23

--

19

Replace the driver outside rearview mirror. Refer to Outside Rearview Mirror Glass Replacement .

Did you complete the replacement?

--

Go to Step 23

--

20

Replace the driver outside rearview mirror. Refer to Outside Rearview Mirror Glass Replacement .

Did you complete the replacement?

--

Go to Step 23

--

21

Replace the inside rearview mirror. Refer to Inside Rearview Mirror Replacement .

Did you complete the replacement?

--

Go to Step 23

--

22

Replace the driver door module. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 23

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23

Operate the system to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2