Q: How Does the Power Mirror Switch Work?

asked by on November 18, 2015

How does the power mirror switch work?

A conventional power mirror switch is essentially two rocker switches built into a single housing. Each rocker switch is connected to two wires that are connected to a reversible DC (direct current) motor inside the rear view mirror on either door. Each rear view mirror has two DC motors. One DC motor operates the up/down function while the other DC motor operates the left/right function.

Both of the rocker switches inside the power mirror switch are constantly connected to the vehicle’s electrical ground circuit with the switch at rest. When you press the switch in any mirror direction, the switch connects one of the two wires of a motor to power (12 volts DC) while keeping the other circuit connected to ground. Electricity then flows through the switch to the DC motor and the mirror head moves in the intended direction. If you press the same switch to the opposite direction, you are reversing the electricity to the mirror motor and the mirror moves in the opposite direction.

For example, let’s adjust the driver’s side rear view mirror. Push the mirror switch to the right, which moves the mirror inward (toward the vehicle). One of the two wires of the L/R mirror motor, wire A, receives power while the other wire, wire B, is connected to ground. This causes the mirror to move inward. Likewise, if you push the mirror switch to the left. Wire A is now connected to ground and wire B is connected to power, causing the L/R mirror motor to move the mirror outward. The same concept occurs when you adjust the mirror up and down.

Many power mirror switches have a neutral or center position, which locks the mirrors in place and prevents any mirror adjustment from occurring.

Newer vehicles utilize control modules (computers) to operate the power mirrors. The power mirror switch is then used to provide a simple command signal to the control module indicating the desired direction. The switch is not directly connected to the mirror motors in this case.

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