Electric rearview mirrors commonly utilize two motors for vertical and horizontal adjustments. The control switch directs voltage to the left or right mirror. With ignition ON and engine OFF, operate the mirror control switch for both mirrors while listening for motor sounds. If the motors sound but the glass doesn't move, there might be an internal drive mechanism issue requiring mirror disassembly. If no motor sound occurs, check the fuse. If the fuse is fine, assess the mirror control switch's continuity after removing it from the dashboard. Reconnect the switch and test for a faulty ground connection by attaching a jumper wire between the ground wire and the switch. If issues persist, remove the mirror and check its wires for voltage using the selector switch. If voltage isn't present, inspect the circuit for opens or shorts. If voltage is present, test the mirror off-vehicle using jumper wires; replace the mirror if it fails this test.