Hummer H3. Manual - part 1357

MIRROR COMPASS DISPLAY INOPERATIVE OR INACCURATE

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The Inside Rearview Mirror (ISRVM) uses 2 magnetic field sensors for compass direction. One
sensor is for north and south, the other is for east and west. The ISRVM supplies a signal and low
reference to each sensor. As the vehicle travels with or against the Earth's magnetic pull, there
will be a change in voltage on one or both sensors. As a result of the change in voltage, the
ISRVM changes the heading on the compass display. The internal fault detection for the compass
is handled by the ISRVM.

Reference Information

Schematic Reference

Inside Rearview Mirror Schematics

Instrument Cluster Schematics

Connector End View Reference

Displays and Gages Connector End Views

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Testing

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Displays and Gages - H3

1. Ignition ON, compass ON, verify that there is a compass reading on the display.

If the display is blank, replace the ISRVM.

If the display shows the letter C or CAL, perform the compass calibration procedure.
Refer to Compass Calibration and Magnetic Variance.

2. Verify that the compass reading on the display is correct.

If not correct, perform the compass magnetic variation adjustment procedure. Refer to
Compass Calibration and Magnetic Variance.

3. If the display is still incorrect, replace the ISRVM.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ISRVM replacement, setup and programming

MIRRORS - TEMPERATURE DISPLAY INACCURATE

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The inside rear view mirror (ISRVM) applies 5 volts to the ambient air temperature sensor. The
ambient air temperature sensor is a thermistor which varies in resistance as the temperature
changes. As the resistance of the ambient air temperature sensor increases, the ISRVM senses a
larger voltage drop across the sensor, indicating a lower temperature. As the resistance of the
ambient air temperature sensor decreases, the ISRVM senses a smaller voltage drop across the
sensor, indicating a higher temperature.

Diagnostic Aids

The following table will be used to measure the resistance of the sensor and compare it with the
actual ambient temperature. The mirror 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

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Displays and Gages - H3

mirror seem off by 5-10 degrees of the actual temperature when it is not.

Ambient Air Temperature Sensor Resistance

Reference Information

Schematic Reference

Inside Rearview Mirror Schematics

Instrument Cluster Schematics

Connector End View Reference

Displays and Gages Connector End Views

°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

71.30

74.58

-10

54.21

56.43

-5

41.48

43.17

32.00

33.31

24.96

25.83

19.61

20.19

15.49

15.94

12.31

12.67

9.85

10.12

7.96

8.15

6.45

6.61

104

5.27

5.39

113

4.32

4.42

122

3.56

3.64

131

2.95

3.02

140

2.46

2.52

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Displays and Gages - H3

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the ambient air temperature sensor. Install

a signal generator and instrument panel tester between the signal circuit and the low
reference circuit.

2. Ignition ON, vary the resistance on the signal generator from 2.5K to 230K. Verify that the

temperature displayed on the ISRVM matches the ambient temperature resistance chart.

If the temperature displayed is incorrect, test the signal circuit and the low reference
circuit for an open/high resistance. If the circuits test normal, replace the ISRVM.

3. If the temperature displayed is correct, replace the ambient air temperature sensor.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ISRVM replacement, setup and programming

MIRRORS - TEMPERATURE DISPLAYS SC OR OC

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The inside rearview mirror (ISRVM) applies 5 volts to the ambient air temperature sensor. The
ambient air temperature sensor is a thermistor which varies in resistance as the temperature

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Displays and Gages - H3

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