Circuit Operation

The Automatic Day-Night Mirror uses two photocell sensors to determine light conditions in the front and back of the vehicle. At night, as the glare of headlamps from behind increases, the mirror gradually becomes darker to absorb the glare. In the daytime, the mirror is in a clear state. With the Ignition Switch in "RUN", battery voltage is applied to terminal 1. Ground feeds terminal 2. With the gear selector lever in reverse, battery voltage is applied to terminal 3 of the mirror. The mirror then gradually changes to a clear state.

An electronic compass is contained within the inside Automatic Day-Night Mirror. The compass display is located on the mirror.

The electronic compass includes a fluxgate magnetic field sensor and a microprocessor. The microprocessor receives inputs from the sensor, processes them and provides outputs to the compass display which indicates the vehicle heading, relative to the Earth's magnetic fields.

Setting The Compass Zone
First determine the correct zone for your location by referring to Figures 1 and 2. Display the compass zone setting by pressing the calibrate switch in the mirror. The calibrate switch can be pressed by inserting the end of a paper clip in the hole on the bottom of the mirror. Press and hold the calibrate switch for 5 seconds or until the zone number appears in the display. To change the current zone setting press and hold the calibrate switch until the correct zone appears Release the switch when the correct zone appears. The display will show compass direction within a few seconds. The zone setting will not be lost when the mirror and the ignition are turned "OFF." The zone require resetting only when the vehicle is outside of the zone for which it is set.

Calibrating The Compass
The compass is an "autocal" compass. This means the mirror will automatically calibrate itself so that the unique magnetic fields in each vehicle do not cause the mirror to display the wrong direction. When the compass is calibrating, a "C" will be displayed. The mirror will calibrate itself during your normal driving routine. When calibration is complete, the "C" in the display will change to the correct directional heading. Once the mirror is calibrated, it will not normally need to be recalibrated. If it does need to be recalibrated it will occur automatically without any input from the driver. Turning the mirror or the vehicle off will not cause the calibration to be lost.

The compass can be manually recalibrated if required. Follow the procedure described:
1. If the "C" is already being displayed, simply drive the vehicle slowly (5 mph or less) in a 360 degree circle until the display reads a compass direction. This will probably calibrate the compass quicker than it would calibrate automatically.
2. If the "C" is not already being displayed, turn the vehicle ignition on and the compass mirror on. Depress the calibrate switch by inserting the end of a paper clip in the hole on the bottom of the mirror and hold it for 10 seconds until the letter "C" appears in the display. The display will show a number first, but keep holding it until the letter "C" appears. Once the letter "C,' appears in the display, drive the vehicle slowly (5 mph or less) in a 360 degree circle until the display reads a compass direction.