The electric rear view mirrors have two motors that are used to make adjustments to the mirror such as one that manages vertical movement and another that manages horizontal movement. The control switch has a switch which sets the flow of current to a right hand mirror or left hand mirror. Keeping the ignition in the ACC position and the engine off, roll down the windows and cycle the mirror control switch in all the functions on both mirrors. In some models the mirrors are also heated by switching the outside mirror control to the heat position. Hear the electric motors, they should be heard but the mirror glass should not move, then the drive mechanism might be faulty so it should be replaced altogether. In case of no sound of the mirrors, verify the Comfort system fuse in the fuse panel. In case the fuses are intact, do not disconnect the wires, but reach the back of the mirror control switch and check the voltage at the switch with the ignition on. A test of continuity in all positions should be made and the switch changed where necessary provided there is a voltage. In the event that the switch is operational, verify the ground connection by hooking a jumper wire in case the mirror is operating, fix the ground. In case the mirror is not responsive, then take off the mirror and inspect whether there is voltage at the mirror wires when the switch is in operation. In case there is no voltage, check the wiring. Test the mirror out of the vehicle using jumper wires and replace in case of any failure in case of voltage. It is to be noted that this system is controlled by the Central Comfort Control Module and any problems therein cannot be diagnosed by a technician without the use of the scan tool by the manufacturer. In case of the inability to solve the problem with simple troubleshooting, then address a dealership or certified repair shop.