GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

DEFINITION: This diagnostic chart should only be used if the compass display is operational.

1

Has the Automatic Day-Night Mirrors System Check been performed?

--

Go to Step 2

Go to Automatic Day-Night Mirrors System Check

2

  1. Turn ignition to the ON position.
  2. Toggle mirror switch to the temperature position.

Is the mirror display totally blank?

--

Go to Step 13

Go to Step 3

3

Are the letters OC displayed on mirror?

--

Go to Step 9

Go to Step 4

4

Are the letters SC displayed on mirror?

--

Go to Step 11

Go to Step 5

5

  1. Locate and disconnect C102.
  2. Check the mirror display.

Are the letters OC displayed?

--

Go to Step 6

Go to Step 13

6

  1. Connect a fused jumper between C102 cavity L and ground.
  2. Check mirror display.

Are the letters SC displayed?

--

Go to Step 7

Go to Step 13

7

By ending up at this step, it is assumed that the temperature display is operating but the displayed temperature is inaccurate.

Refer Automatic Day-Night Mirrors System Check to check accuraccy of temperature sensor.

Did you find acceptable temperature/resistance values?

--

Go to Step 13

Go to Step 8

8

Replace the outside air temperature sensor. Refer to Ambient Air Temperature Sensor Replacement .

Is the repair complete?

--

System OK

--

9

The letters OC stand for Open Circuit or outside temperature is -40° F (-40° C) or lower.

Is outside temperature -40° F (-40° C) or lower?

--

System OK

Go to Step 10

10

Locate and repair the open in the following:

    • Circuit 735 (LT GRN/BLK) between automatic day-night rearview mirror and outside air temperature sensor.
    • Circuit 718 (BRN) between automatic day-night rearview mirror and outside air temperature sensor.
    • Outside air temperature sensor.

Is the repair complete?

--

System OK

--

11

The Letters SC stand for short circuit or outside temperature is 140° F (60° C) or higher.

Is outside temperature 140° F (60° C) or higher?

--

System OK

Go to Step 12

12

Locate and repair short to ground in the following:

    • Circuit 735 (LT GRN/BLK) between automatic day-night rearview mirror and outside air temperature sensor.
    • Circuit 718 (BRN) between automatic day-night rearview mirror and outside air temperature sensor.
    • Outside air temperature sensor.

Is the repair complete?

--

System OK

--

13

Replace Automatic Day-Night Mirror assembly. Refer to Inside Rearview Mirror Replacement .

Is the repair complete?

--

System OK

--