Automatic Day-Night Mirror System Components
The automatic day-night mirror system consist of the following components:
| • | Ambient air temperature sensor |
Automatic Day-Night Mirror Operation
With the ignition switch in the ON position, accessory voltage is supplied
through the SUNROOF fuse, in the IP fuse block, to the inside rearview mirror.
The inside rearview mirror uses 2 photocell sensors in order to determine
light conditions in the front and the back of the vehicle.
At night, with the automatic day-night feature enabled, the mirror
automatically darkens to reduce the glare from the headlamps from
behind. In the daytime, the mirror is in a normal state. 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 will gradually change to a normal state
as a result of the backup lamp supply voltage input. Ground for
the inside rearview mirror is provided by G302.
Temperature Display
The inside rearview mirror supplies a 5 volt signal circuit and
low reference circuit to the ambient air temperature sensor. The inside rearview
mirror monitors and records the voltage on the signal circuit of
the ambient air temperature sensor. The inside rearview mirror uses
this recorded voltage to display the temperature on the temperature
display portion of the compass/temperature display. The temperature
display will show "ICE" when the ignition is first turned
on and the current temperature is 3°C (37°F) or
below. The display will toggle between "ICE" and the
actual outside temperature for approximately 4 minutes.
The mirror will display "OC" if the mirror senses a temperature
of less than -40°C (-40°F).
the mirror will display a "SC" if the mirror senses a temperature
of greater than 112°C (143°F ).
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. |
Compass
The electronic compass includes a magnetic field sensor and a microprocessor.
The microprocessor receives inputs from the sensor, processes these
inputs, and provides a heading on the compass display.
Switches of the Inside Rearview Mirror with the Automatic Day-Night
Feature (w/oOnStar®)
The inside rearview mirror has two switches that perform the following
functions:
| • | The TEMP switch is used to enable or disable the temperature display
and the automatic day-night feature of the mirror. With the ignition in the
ON position, depress the TEMP switch to enable the temperature display.
Depress the TEMP switch again to disable the temperature display.
The TEMP switch can be held for 8 seconds in order to change the
display from Fahrenheit (°F) to Celsius (°C), or from Celsius
(°C) to Fahrenheit (°F). Depress the TEMP switch for
15 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 the TEMP switch for 15 seconds. |
| • | The COMP switch is used to turn the compass on and off. With the
ignition in the ON position, depress the COMP switch to turn the compass on.
Depress the COMP switch again to turn the compass 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 (w/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
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/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 briefly pressed 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. |
