Most electric rear view mirrors use two motors for movement - one for up-down adjustments and one for left-right adjustments. The control switch sends voltage to the left or right mirror. With the ignition ON but engine OFF, roll down windows and operate the mirror control switch through all functions for both mirrors. Listen for motor sounds. If motors run but glass doesn't move, there's a problem with the drive mechanism. If mirrors don't operate and no sound is heard, check the
Fuse. If fuse is OK, have the switch continuity checked. Test ground connections. If mirror still doesn't work, check wires for voltage. If no voltage, check circuit for opens and shorts. If there's voltage, test mirror off the vehicle. Replace if it fails.