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:
| • | Driver outside rearview mirror with the automatic day-night feature |
| • | Ambient air temperature sensor |
Inside Rearview Mirror with the Automatic Day-Night Feature System Operation
With the ignition switch in the ON position, ignition 1 voltage is
supplied through the IGN 1 fuse in the left I/P fuse block to the inside
rearview mirror. Ground for the inside rearview mirror is provided by G203.
The inside rearview mirror has 2 photocell sensors. The headlight sensor,
located on the front of the mirror or mirror face. The headlight sensor is used
to detect a high light condition such as headlights from a car behind. The ambient
light sensor located on the back of the mirror or windshield side. The ambient light
sensor is used to detect a low light or nighttime condition. In a low light or nighttime
condition, with the automatic day-night feature enabled, the mirror will automatically
darken the face to reduce the glare from the headlights. With the gear selector lever
in the REVERSE position, backup lamp supply voltage is supplied as an input to the
inside rearview mirror. This disables the automatic day-night feature of the mirror
and allows the face to gradually change to a normal state. In the daytime, the mirror
is in a normal state because of the high light condition that is detected by the
ambient light sensor.
The inside rearview mirror will also darken the driver outside rearview mirror.
The inside rearview mirror supplies a signal and a low reference to the driver outside
rearview mirror. Refer to
Outside Mirror Description and Operation
in Doors for further description and operation of the driver
outside rearview mirror.
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 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 mirror changes the heading on the compass display.
Temperature Display
The inside rearview mirror supplies a 5 volt signal circuit and low
reference circuit to the ambient air temperature sensor. As the outside air temperature
gets warmer, the ambient air temperature sensor will pull the voltage lower on the
5 volt signal circuit. The inside rearview mirror monitors this voltage and
will show this as a warmer temperature on the display. Temperatures exceeding 112°C
(143°F) will be out of the mirror's temperature range which SC will be shown
on the temperature display. In colder outside air temperatures, the ambient air temperature
sensor will not pull the voltage as low on the 5 volt signal circuit. The
inside rearview mirror will show a colder temperature on the display. Temperatures
exceeding -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 for 2 minutes. The
mirror will increase the last temperature reading by one degree every 2 minutes
for the 8 consecutive times. If the outside temperature is not matched after the
8th update, 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, 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, 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
. |
| • | The three switches on the right side of the mirror are for OnStar®
operation. For more information, refer to
OnStar Description and Operation
in Cellular Communications. |
