The wiper motor switch connects power from the car's battery to the motor winding to start the wiper motor spinning and controls the flow of current to the wiper motor. The wiper motor switch is responsible for starting and stopping the wiper motor and selecting and regulating the speed.
The driver can decide at what speed the wipers move, usually from a choice of three speeds, depending on the weather conditions. The driver can operate the wipers by selecting the desired speed on the wiper switch stalk, which is usually mounted on the steering column. This activates the wiper motor switch, which operates with a wiper motor relay. When the wiper motor switch is activated by the driver via the controls on the wiper stalk switch, an electric current is sent to the wiper motor and the copper motor winding picks up this current, causing the electricity to move through the winding. The electricity moving through the copper wire creates a circular magnetic field. It is this magnetic energy which generates the force to power the cylinder and makes it spin. The spinning cylinder creates the energy needed to power the motor which in turn powers the wiper mechanism.
The wiper motor switch operates with a wiper motor relay which opens or closes the circuit. The wiper motor relay uses an electromagnet to mechanically operate the wiper motor switch. The relay is made up of a coiled wire which is attached to a strong magnetic base, such as iron, which generates a magnetic field when the electric current flows through it, which activates the wiper motor switch and either opens or closes the connection. The relay has a hinged mechanism which enables the switch to move, which either starts or stops the current to the motor. When the wipers have been set to the off position on the wiper stalk switch, the wiper motor switch is designed to interrupt the flow of current from the battery to the motor. The wiper motor switch controls the levels or voltage of the current flowing to the motor, to enable the different speed settings which can be chosen by the driver. When a slow or medium speed setting is selected by the driver, when the motor has reached the necessary speed for the chosen setting, the wiper motor switch, with the mechanism of the motor relay, activates or deactivates according to the rotating speed of the motor. The windscreen wiper arms are programmed to automatically return to the park position when the wipers have been switched to off, which means they will not obstruct the driver's view when not in use. The controller for intermittent wiper mode is often built into the wiper motor switch.
Car electrical switches will slowly wear out over time and will last only a certain number of years before they will need replacing. If the wiper motor switch is not working it is worth checking to see if it is just a matter of some loose wires that need tightening. If this doesn't sort the problem it is likely that the switch is broken. Buying a wiper motor switch will ensure you get a part that will be compatible with the make and model of your vehicle.