POWER WINDOWS, LOCKS, & MIRRORS
by Kyle McFadden

POWER WINDOWS
Power windows are raised and lowered using a permanent magnet electric motor. The motor will actuate a regulator that is attached to the glass. Motor operation is controlled by reversing polarity of the voltage to the motor. The power window switch controls the power and ground circuits. When the window is commanded down, voltage is supplied to one side of the motor and ground to the other. When the window is commanded up, voltage and ground circuits are reversed causing the motor to spin the opposite direction, raising the window. Power window motors are attached to the door or the window regulator in a position in which the drive gear on the motor can contact the gear on the regulator. Some window regulators use a tensioned helper spring that assist the power window motor in raising the glass. An auto repair manual with wiring diagrams will provide the details specific to your automobile.

POWER DOOR LOCKS
A power door lock system uses reversible motors to perform the lock and unlock functions for each door. Similar to power window motors, power door lock function is actuated by changing polarity of the current flowing to the motors. The interior power door lock switch controls the power and ground circuits for all doors. On most model vehicles, operating the power door locks using the door lock switches will lock or unlock every door in unison. Failure of one door lock to function, can normally be isolated to a problem in that particular door. Some power door lock motors can contain an internal circuit breaker that will trip if amperage load is exceeded. Failure of the entire door lock system can usually be attributed to a power supply problem. Vehicles that are equipped with a keyless entry system use a module to control the door lock functions. A keyless entry module will receive a signal from the transmitter and operate a relay that controls door lock function. The relay will operate the same circuits used by the interior door lock switches. These systems will usually unlock the drivers door lock on one command, and the remaining door locks on the second. This feature is for security reason only. Lock function is the same as with conventional power door locks, all doors will be locked at once. Diagnosing and troubleshooting the power door locks requires a wiring diagram which can be found in an auto repair guide specific to your car’s year, make, and model.

POWER MIRRORS
Power outside rear view mirror positioning is achieved by the use of two reversible electric motors mounted inside each mirror. Left to right mirror positioning is actuated by one motor, while up and down positioning is actuated by the other. Power and ground circuits are supplied through the power mirror switch. The rear view mirror switch positions the mirror by changing the polarity of the motor circuits in response to operator input.

(Kyle has an affinity for Pale Ale and tooling on his 1956 Chevrolet Nomad Station Wagon.)