GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2007 🢒 H2 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Mirrors - Temperature Displays SC or OC
Table 1: Ambient Air Temperature Sensor Resistance

The following table will be used to measure the resistance of the sensor and compare it with the actual ambient temperature. The mirror's temperature accuracy should be within 5 degrees of the actual temperature. The actual temperature should not be taken from a radio station, a sign displaying the temperature, etc. A temperature measuring tool such as a thermometer should be used. Some temperature measuring tools may be within 5 degrees of the actual temperature. Make sure to consult the manufacturer for the accuracy of the tool. This comparison can make the mirror seem off by 5-10 degrees of the actual temperature when it is not.

Ambient Air Temperature Sensor Resistance

°C

°F

Minimum Resistance

K Ohms

Maximum Resistance

K Ohms

-35

-31

234.81

250.59

-30

-22

171.69

182.31

-25

-13

126.82

133.99

-20

-4

94.63

99.49

-15

5

71.30

74.58

-10

14

54.21

56.43

-5

23

41.48

43.17

0

32

32.00

33.31

5

41

24.96

25.83

10

50

19.61

20.19

15

59

15.49

15.94

20

68

12.31

12.67

25

77

9.85

10.12

30

86

7.96

8.15

35

95

6.45

6.61

40

104

5.27

5.39

45

113

4.32

4.42

50

122

3.56

3.64

55

131

2.95

3.02

60

140

2.46

2.52

Step

Action

Yes

No

Schematic Reference: Inside Rearview Mirror Schematics

Connector End View Reference: Mirror Connector End Views

1

Did you review the temperature display operation of the inside rearview mirror and perform the necessary inspections?

Go to Step 2

Go to Automatic Day-Night Mirror Description and Operation

2
  1. Turn ON the ignition, with the engine OFF.
  2. Turn ON the temperature display on the inside rearview mirror.

Does the temperature display show a temperature reading?

Go to Step 3

Go to Step 5

3

Does the temperature display show an accurate temperature reading?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 4

4
  1. Turn OFF the ignition.
  2. Disconnect the ambient air temperature sensor.
  3. Measure the resistance of the ambient air temperature from the sensor signal circuit to the low reference circuit of the sensor.
  4. Compare the ambient air temperature sensor resistance reading with the chart above.

Is the ambient air temperature sensor resistance within the range specified in the chart above?

Go to Step 12

Go to Step 13

5

Does the temperature display show SC?

Go to Step 6

Go to Step 7

6
  1. Turn OFF the ignition.
  2. Disconnect the ambient air temperature sensor.
  3. Turn ON the ignition, with the engine OFF.

Does the temperature display show SC?

Go to Step 9

Go to Step 13

7
  1. Turn OFF the ignition.
  2. Disconnect the ambient air temperature sensor.
  3. Connect a 3-amp fused jumper between the signal circuit of the ambient air temperature sensor and a good ground.
  4. Turn ON the ignition, with the engine OFF.

Does the temperature display show SC?

Go to Step 8

Go to Step 10

8
  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper between the signal circuit and the low reference circuit of the ambient air temperature sensor.
  3. Turn ON the ignition, with the engine OFF.

Does the mirror temperature display show SC?

Go to Step 13

Go to Step 11

9

Test the signal circuit of the ambient air temperature sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 14

10

Test the signal circuit of the ambient air temperature sensor for an open or for a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 14

11

Test the low reference circuit of the ambient air temperature sensor for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 14

12

Test the signal and low reference circuits of the ambient air temperature sensor for high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 14

13

Inspect for a poor connection at the harness connector of the ambient air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 15

14

Inspect for a poor connection at the harness connector of the inside rearview mirror. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 16

15

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

Did you complete the replacement?

Go to Step 17

--

16

Replace the inside rearview mirror. Refer to Control Module References for replacement, setup, and programming and Inside Rearview Mirror Replacement .

Did you complete the replacement?

Go to Step 17

--

17

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3