Inside Rearview Mirror

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:
^ Inside rearview mirror
^ Driver outside mirror with the automatic day-night feature

POWER AND GROUND OF THE INSIDE REARVIEW MIRROR
^ With the ignition ON, ignition voltage is supplied to the mirror from the IGN 1 fuse in the rear fuse block.
^ Ground for the mirror is provided by G402.

INSIDE REARVIEW MIRROR WITH THE AUTOMATIC DAY-NIGHT FEATURE SYSTEM OPERATION
The inside rearview mirror uses 2 photocell sensors. 1 sensor is the headlight sensor, located on the front of the mirror or mirror face. 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 back of the mirror or windshield side. The ambient light sensor is used to determine light conditions present at the mirror. With automatic day-night feature enable, the mirror uses ambient light sensor to determine if the present light condition. With a low light condition detected, and a high light condition such as headlights from a car behind is present at the headlight sensor. The inside rearview mirror will automatically darken the face of the mirror to reduce the glare from the headlights from behind. In the daytime, the mirror is in a normal state because of the high 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. In night time conditions only, the mirror monitors this input to disable the automatic day-night feature which allows the face to gradually change to a normal state. This allows the driver to see objects in the mirror clearly when backing up.

DRIVER OUTSIDE REARVIEW MIRROR WITH THE AUTOMATIC DAY-NIGHT FEATURE OPERATION
The inside rearview mirror will also darken the driver outside rearview mirror. The inside rearview mirror supplies a low reference circuit and a signal circuit 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.

SWITCHES OF THE INSIDE REARVIEW MIRROR WITH THE AUTOMATIC DAY-NIGHT FEATURE
The inside rearview mirror has 2 switches that perform the following functions:
^ The AUTO switch is used to enable the automatic day-night feature of the mirror. With the ignition in the ON position, depress the AUTO 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.
^ The OFF switch is used to disable the automatic day-night feature of the mirror.

SWITCHES OF THE INSIDE REARVIEW MIRROR WITH THE AUTOMATIC DAY-NIGHT FEATURE AND COMPASS WITHOUT ONSTAR(R)
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 Variance Procedure.

SWITCHES OF THE INSIDE REARVIEW MIRROR WITH THE AUTOMATIC DAY-NIGHT FEATURE WITH COMPASS AND ONSTAR(R)
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 Variance Procedure
^ The 3 switches on the right side of the mirror are for OnStar(R) operation. For more information, refer to OnStar Description and Operation in Cellular Communication.

COMPASS CALIBRATION AND VARIANCE PROCEDURE

Compass Calibration
Before calibrating the compass, drive the vehicle to an area that is magnetically clean or free of large metallic objects. Verify there are no magnetized objects on the inside or outside of the vehicle close to the mirror.
1. Start the engine.
2. Press and hold the switch for the compass, which may be depicted as COMP, COMPASS, or on/off (W/UE1) depending on the type of mirror on the vehicle, until the letter C" or "CAL" is displayed.
3. Drive the vehicle in circles at a speed of less than 8 km/h (5 mph) until the "C" or "CAL" is replaced by a proper vehicle heading. The calibration procedure is now complete.

Compass Magnetic Variation Adjustment
Magnetic variation adjustments are required when the compass displays a constant error in heading. Variation is the difference between magnetic north and true north due to geographical location.

World Magnetic Variation Map:

1. Locate your current geographic location on the World Magnetic Variation Map.
2. Turn ON the ignition, with the engine OFF.
3. Press and hold the switch for the compass, which may be depicted as COMP, COMPASS, or on/off (W/UE1) depending on the type of mirror on the vehicle, until a zone number appears on the compass display.
4. Depress the switch for the compass to select the desired zone number.
5. Wait 5 seconds. The display will return to a compass heading. The variance procedure is now complete.

For a description of the RPO Code(s) shown in this article or any of the images therein, refer to the RPO Code List found at Vehicle/Application ID". RPO Codes