Inside Rearview Mirror with the Automatic Day-Night Feature System Components
The inside rearview mirror with the automatic day-night feature system consist of the following components:
| • | Ambient air temperature sensor |
Power and Ground of the Inside Rearview Mirror
With the ignition ON, ignition voltage is supplied to the mirror from the IGN E fuse in the underhood fuse block. Ground for the mirror is provided by G302.
Inside Rearview Mirror with the Automatic Day-Night Feature System Operation
The inside rearview mirror uses 2 photocell sensors. One sensor is the headlight sensor, located on the face side of the mirror. The headlight sensor is used to determine light conditions present at the mirror face. The other sensor is the ambient
light sensor, located on the rear of the mirror or windshield side. The ambient light sensor is used to determine the exterior light conditions. With a low exterior light condition detected, and a high light condition from behind of the car, at the headlight
sensor, the inside rearview mirror will automatically darken the face of the mirror.
In the daytime, the mirror is in a normal state because of the high exterior light condition that is indicated by the ambient light sensor. With the gear selector lever in the REVERSE position, backup lamp supply voltage is supplied as an
input to the inside rearview mirror. The mirror monitors this input to disable the automatic day-night feature. This allows the driver to see objects in the mirror clearly when backing up, even during the night.
Compass
The mirror uses two magnetic field sensors for compass direction. One sensor is for north and south, the other is for east and west. The mirror supplies a signal and low reference to each sensor. As the vehicle travels with or against the earths magnetic
pull, there will be a change in voltage on one or both sensors. As a result of the change in voltage, the mirror changes the heading on the compass display.
Temperature Display
The inside rearview mirror monitors the ambient air temperature sensor. As the outside air temperature gets warmer, the ambient air temperature sensor will lower resistance. The inside rearview mirror monitors this change and will show this as a warmer
temperature on the display. Temperatures exceeding 62°C (143°F) will be out of the mirrors temperature range and SC will be shown on the temperature display. In colder outside air temperatures, the ambient air temperature sensor will raise in resistance.
The inside rearview mirror will show a colder temperature on the display. Temperatures lower than -40°C (-40°F) will be out of the mirror's temperature range which OC will be shown on the temperature display. In cold temperatures such as
3°C (37°F) or below, the temperature display will show ICE when the ignition is first turned on. The display will toggle between ICE and the actual outside temperature until the temperature update process is complete.
Temperature Display Update Process
The inside rearview mirror has a temperature program that takes in account the fact that the radiator will heat the ambient air temperature sensor if the radiator is warm and the vehicle is not moving. If the vehicle has been off for more than 2 hours,
the mirror temperature program assumes that the radiator has cooled and that the temperature supplied by the ambient air temperature sensor is accurate. Because of this, if the vehicle has been off for more than 2 hours, the mirror displays the temperature
as reported by the ambient air temperature sensor. When the ambient air temperature sensor reports a new temperature to the mirror, one of the following cases will apply:
| • | Ignition is OFF for more than 2 hours, then is turned ON for more than 3 minutes. The outside temperature is greater than the last temperature recorded by the mirror for 2 minutes. The mirror will increase the last temperature
reading by one degree every 2 minutes for 8 consecutive times. If the outside temperature is not matched after the 8th update, the mirror will then display the current outside temperature. |
| • | Ignition is off for more than 2 hours, then is turned ON for less than 3 minutes. The mirror will update the temperature display every 2 seconds. |
| • | Ignition is OFF for more than 2 hours, then is turned ON for more than 3 minutes. The outside temperature is less than the last temperature recorded by the mirror. The mirror will then display the current outside temperature. |
| • | Ignition has been OFF for less than 2 hours. The outside temperature is greater than the last temperature recorded by the mirror, but the ignition is cycled from ON to OFF within 2 minutes. The mirror will display the old temperature. |
| • | Ignition has been OFF for less than 2 hours. The outside temperature is less than the last temperature recorded by the mirror. The mirror will then display the current outside temperature. |
Switches of the Inside Rearview Mirror with the Automatic Day-Night Feature and Compass without OnStar®
The inside rearview mirror has 2 switches that perform the following functions:
| • | The MIRROR switch is used to enable or disable the automatic day-night feature of the mirror. With the ignition in the ON position, depress the MIRROR switch to enable the automatic day-night feature of the mirror. A green indicator will illuminate
on the mirror when the automatic day-night feature is enabled. To disable the automatic day-night feature of the mirror, depress the MIRROR switch. |
| • | The COMPASS switch is used to turn the compass on and off. With the ignition in the ON position, depress the COMPASS switch to turn the compass on. Depress the COMPASS switch again to turn the compass off. The COMPASS switch is also used to place
the compass into a calibration or zone mode. For more information, refer to
Compass Calibration and Magnetic Variance. |
Switches of the Inside Rearview Mirror with the Automatic Day-Night Feature, Compass/Temperature Display without OnStar®
The inside rearview mirror has two switches that perform the following functions:
| • | The TEMP switch is used to turn the compass/temperature display on or off, It is also used to enable or disable the automatic day-night feature of the mirror. With the ignition in the ON position, depress the TEMP switch to enable the compass/temperature
display. Depress the TEMP switch again to disable the compass/temperature display. The TEMP switch can be held for 4 seconds in order to change the display from Fahrenheit (°F) to Celsius (°C), or from Celsius (°C) to Fahrenheit (°F).
Depress the TEMP switch until the green indicator illuminates on the mirror. This indicates that the automatic day-night feature is enabled. To disable the automatic day-night feature of the mirror, depress the TEMP switch until the green indicator turns off. |
| • | The COMP switch is used to turn the compass/temperature display on or off. With the ignition in the ON position, depress the COMP switch to turn the compass/temperature display on. Depress the COMP switch again to turn the compass/temperature display
off. The COMP switch is also used to place the compass into a calibration or zone mode. For more information, refer to
Compass Calibration and Magnetic Variance. |
Switches of the Inside Rearview Mirror with the Automatic Day-Night Feature with Compass and OnStar®
The inside rearview mirror has 4 switches that perform the following functions:
| • | The on/off switch located at the left side of the mirror performs the following functions: |
| - | To enable or disable the automatic day-night feature of the mirror. With the ignition in the ON position, depress and hold the on/off switch for 4 seconds to enable the automatic day-night feature of the mirror. A green indicator will illuminate
on the mirror when the automatic day-night feature is enabled. To disable the automatic day-night feature of the mirror, depress and hold the on/off switch for 4 seconds. |
| - | To turn the compass on and off. With the ignition in the ON position, depress the on/off switch to turn the compass on. Depress the on/off switch again to turn the compass off. The on/off switch is also used to place the compass into a calibration
or zone mode. For more information, refer to
Compass Calibration and Magnetic Variance. |
Switches of the Inside Rearview Mirror with the Automatic Day-Night Feature, Compass/Temperature Display with OnStar®
The inside rearview mirror has four switches that perform the following functions:
| • | The on/off switch located at the left side of the mirror performs the following functions: |
| - | To enable or disable the automatic day-night feature of the mirror. With the ignition in the ON position, depress and hold the on/off switch for 6 seconds to enable the automatic day-night feature of the mirror. A green indicator will illuminate
on the mirror when the automatic day-night feature is enabled. To disable the automatic day-night feature of the mirror, depress and hold the on/off switch for 6 seconds. |
| - | To turn the compass/temperature display on and off. With the ignition in the ON position, depress the on/off switch to turn the compass/temperature display on. Depress the on/off switch again to turn the compass/temperature display off. The on/off
switch can be held for 4 seconds in order to change the display from Fahrenheit (°F) to Celsius (°C), or from Celsius (°C) to Fahrenheit (°F). The on/off switch is also used to place the compass into a calibration or zone mode. For more
information, refer to
Compass Calibration and Magnetic Variance. |
