Most electric rear view mirrors have two motors for adjusting the glass - one for up and down and one for left and right. Some mirrors also have electrically heated glass defroster circuits. To troubleshoot, roll down the windows and operate the mirror control switch through all functions. Listen for motor sounds. If the glass doesn't move but the motors are running, there may be a problem with the drive mechanism. Check the
Fuse if the mirrors don't operate and there's no sound. If the fuse is fine, check for voltage at the switch. If there's no voltage, check the wiring. If there's voltage, check the switch for continuity. If the switch is faulty, replace it. Check the ground connection and the wires at the mirror for voltage. If there's no voltage, check the wiring. If there's voltage, test the mirror off the vehicle. Replace if necessary.