i have just recently installed a electronic compass/temp mirror out of a 1998 gmc truck into a 1992 /how do u reset the mirror the compass reads the wrong direction

This is all I was able to find.

Electrochromic Rearview Mirror
When on, an electrochromic mirror automatically dims to the proper level to minimize glare from lights behind you after dark. There is no tab to change the angle because driver intervention is not required.
You can find more information in your Owner'* Manual on page 2-59.

Electrochromic Rearview Mirror
The definition of electrochromic is, "the science of reversibly darkening materials by applying electricity."
Electrochromic gel has been around for more than 20 years. On the 2002 Avalanche the gel is sandwiched between two pieces of glass, each of which has been treated with a transparent, electrically conductive coating, and one with a reflector. A forward-facing sensor recognizes low ambient light levels and signals the mirror to begin looking for glare. A rearward-facing sensor then detects glare from the vehicles traveling behind you (or bright sun from a sunrise or sunset low to the horizon), sending voltage to the mirror'* gel in proportion to the amount of glare detected. The mirror dims in proportion to the glare and then clears when the glare is no longer detected.
You can find more information by visiting Gentex.Com.

Electrochromic Rearview Mirror
Each time the vehicle is started, the electrochromic mirror is activated. If you do not want it on, then you will have to manually turn it off. Press and hold the TEMP button on your rearview mirror for six seconds. The indicator light to the right of the TEMP button will turn off when the mirror is off. To turn it back on hold the TEMP button again for six more seconds, and the indicator light will come back on.
You can find more information in your Owner'* Manual on page 2-60.

Electrochromic Rearview Mirror
When cleaning the mirror, use a soft terry towel cloth, lens cleaning paper, or similar material dampened with window cleaner. Do not spray window cleaner directly on the mirror as that may cause the liquid cleaner to enter the mirror housing.
You can find more information in your Owner'* Manual on page 2-60.

Compass and Temperature Display
In order to have the compass and temperature display, you must press the compass or temperature button. If the display disappears, you may have pressed one of these buttons by accident.
You can find more information in your Owner'* Manual on page 2-60.

Compass Variance
The compass in your Chevrolet Avalanche allows you to set the variance between magnetic north and true north, depending upon your location in North America. The mirror is set in zone eight upon leaving the factory. It will be necessary to adjust the compass to compensate for compass variance if you live outside zone eight. Under certain circumstances, as during a long distance cross-country trip, it will be necessary to adjust for compass variance. If you do not adjust your compass to account for compass variance, your compass can give false readings. To adjust for compass variance, do the following:

1. Use the COMP button located at the bottom of the mirror.
2. Press and hold the COMP button for three seconds until a zone number appears in the display.
3. Find your current location on the map provided on this web page.
4. Press the COMP button on the bottom of the mirror until the new zone number appears in the display. After you stop pressing the button in, the display will show a compass direction within a few seconds.

If you disconnect the power to your Avalanche, or if your Avalanche loses power, it will be necessary to reset the compass variance.