Most electric rear view mirrors utilize two motors for adjustments,one for vertical movement and another for horizontal movement. Some mirrors also feature electrically heated glass defroster circuits, typically powered through the rear window defogger relay. The control switch includes a selector that directs voltage to either the left or right side mirror. With the ignition ON but the engine OFF, roll down the windows and operate the mirror control switch through all functions for both mirrors, listening for the sound of the electric motors. If the motors are audible but the mirror glass remains stationary, the drive mechanism inside the mirror may be faulty, necessitating removal and disassembly to identify the issue. If there is no sound from the mirrors, check the fuse. If the fuse is intact, remove the mirror control switch without disconnecting the wires, turn the ignition ON, and check for voltage at the switch. Voltage should be present at one terminal; if absent, inspect the wiring between the fuse panel and the switch for faults. If voltage is detected, disconnect the switch and test for continuity in all operating positions. If continuity is lacking, replace the switch. Reconnect the switch and locate the ground wire; connecting a jumper wire between this wire and ground can indicate a faulty ground connection if the mirror operates normally. If the mirror remains unresponsive, check the wires at the mirror for voltage using a test light while the ignition is ON and the selector switch is in the appropriate position. There should be voltage at one of the switch-to-mirror wires in each position, except the neutral "off" position. If no voltage is found, inspect the wiring between the mirror and control switch for issues. If voltage is present, remove the mirror and test it off the vehicle with jumper wires, replacing it if it fails the test.