GM Service Manual Online
For 1990-2009 cars only

Diagnostic Aids

The automatic day-night feature of the left outside rearview mirror may be inoperative due to the automatic day-night mirror signal circuit being shorted to battery positive voltage. When this condition occurs, both the left outside rearview mirror and the inside rearview mirror will be in a darkened state. Both mirrors will be permanently damaged and will need to be replaced.

Step

Action

Value(s)

Yes

No

SCHEMATIC REFERENCE: Outside Rearview Mirror Schematics

1

Did you perform the Door Systems Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Door Systems

2

  1. Turn ON the ignition, with the engine OFF.
  2. Turn ON the automatic day-night feature of the inside rearview mirror.
  3. Cover the sensor on the back of the inside rearview mirror.
  4. Shine a bright light into the sensor on the face of the inside rearview mirror.

Does the inside rearview mirror darken?

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Go to Step 3

Go to Automatic Day-Night Mirrors Inoperative in Stationary Windows

3

While shining a bright light into the sensor on the face of the inside rearview mirror, observe the left outside rearview mirror.

Does the left outside rearview mirror darken?

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

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the harness connector of the left outside rearview mirror (connector C2 w/A45) (connector C3 w/o A45).
  3. Turn ON the ignition, with the engine OFF.
  4. Turn ON the automatic day-night feature of the inside rearview mirror.
  5. Cover the sensor on the back of the inside rearview mirror.
  6. Shine a bright light into the sensor on the face of the inside rearview mirror.
  7. Measure the voltage between the signal circuit and the low reference circuit of the automatic day-night mirror, at the harness connector of the left outside rearview mirror.

Is the voltage within the specified range?

0.75-1.5 V

Go to Step 7

Go to Step 5

5

Is the voltage measured in step 4 greater than the specified value?

1.5 V

Go to Step 13

Go to Step 6

6

Measure the voltage between the signal circuit of the automatic day-night mirror and a good ground.

Is the voltage within the specified range?

0.75-1.5 V

Go to Step 9

Go to Step 8

7

  1. Turn OFF the ignition.
  2. Connect the harness connector of the left outside rearview mirror (connector C2 w/A45) (connector C3 w/o A45).
  3. Carefully disconnect the mirror face of the left outside rearview mirror. Refer to Mirror Face Replacement - Outside Electrochromatic .
  4. Turn ON the ignition, with the engine OFF.
  5. Turn ON the automatic day-night feature of the inside rearview mirror.
  6. Cover the sensor on the back of the inside rearview mirror.
  7. Shine a bright light into the sensor on the face of the inside rearview mirror.
  8. Measure the voltage between the signal circuit and the low reference circuit of the automatic day-night mirror at the mirror face harness connectors.

Is the voltage within the specified range?

0.75-1.5 V

Go to Step 10

Go to Step 11

8

Test the signal circuit of the automatic day-night mirror between the mirror harness connector and the inside rearview mirror for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find or correct the condition?

--

Go to Step 17

Go to Step 12

9

Test the low reference circuit of the automatic day-night mirror between the mirror harness connector and the inside rearview mirror for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find or correct the condition?

--

Go to Step 17

Go to Step 12

10

Inspect for poor connections at the harness connector of the left outside rearview mirror face. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find or correct the condition?

--

Go to Step 17

Go to Step 14

11

Inspect for poor connections at the harness connector of the left outside rearview mirror. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find or correct the condition?

--

Go to Step 17

Go to Step 15

12

Inspect for poor connections at the harness connector of the inside rearview mirror. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find or correct the condition?

--

Go to Step 17

Go to Step 16

13

Important:: A short to battery positive voltage on the signal circuit of the automatic day-night mirror will cause permanent damage to both the left outside rearview mirror and the inside rearview mirror.

Repair the short to voltage in the signal circuit of the automatic day-night mirror. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 17

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14

Replace the left outside rearview mirror face. Refer to Mirror Face Replacement - Outside Electrochromatic .

Did you complete the replacement?

--

Go to Step 17

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15

Replace the left outside rearview mirror. Refer to Outside Rearview Mirror Motor Replacement .

Did you complete the replacement?

--

Go to Step 17

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16

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

Did you complete the replacement?

--

Go to Step 17

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17

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 2