The car wiper motor is the component that powers the windshield wipers. As it spins, a mechanism built to it rotates a worm gear, arm and, finally, the windshield or windscreen wiper blades. The wiper blades then rid the windscreen of water, snow, dust, or any other debris that may affect visibility when driving.
Car wiper motors form part of the wiper system. Because they help clear the windshield, they are usually viewed as one of the car safety components. Other parts of the wiper system include wiper linkage, wiper washer pump, and wiper switch. Some of these parts, such as the wiper switch are placed near the driver, but where is the windshield wiper motor located?
The wiper motor assembly is commonly found in the engine bay and often mounted firewall. From there, it connects to the parts that make the wiper linkage, helping to transmit motion and move the wiper arms and blades. The image below shows the windshield wiper motor location.
Although the standard location of a wiper blade motor is the engine bay, just below the wiper cowl, it’s not the only place to find it. Some cars such as hatchbacks, for example, are fitted with rear wipers. In addition to the front wiper motor, these will also have a separate rear wiper motor or what’s often called rear window wiper motor.
The conventional front or rear windshield wiper motor is an assembly of metal and plastic components. Costly models feature more metal parts than plastic, making them more robust and durable. In terms of design, wiper motors mostly differ in the gear arrangement, control mechanism, and transmission parts.
Having looked at the basics of a vehicle wiper motor, it’s now time to get into assembly and learn about the different components that make it.
The wiper motor assembly isn’t just a motor, and consists of many different components. These include the motor itself, gear mechanism, connectors, switch, and more. Here is a list of the main parts of a wiper motor including their specific functions.
The heart of motor vehicle windshield wipers is a DC motor, which can be rated 6V, 12V, or 24V. Most motors are run off a 12V source, while a few are rated 6V and 24V. The parts of the motor include the following.
Housing- made from steel, the wiper motor housing encloses and protects the parts inside. It’s often coated to prevent corrosion.
Magnet- the windshield wiper’s motor today contains permanent magnets. These are usually attached to the inside of the housing using adhesive. Their function is to provide the magnetic force required to rotate the armature. Older wiper motors used electromagnets/field magnets instead of permanent magnets
Armature- the armature is the rotating center piece. It consists of a coil of copper wire would around a magnetic core and resting on a shaft. The shaft spins freely, with a small bearing at the end for a smooth rotation.
Brushes- the wiper motor brushes provide the path through which current is conducted to the armature coil so the motor can rotate. Modern car wiper motors come equipped with 3 brushes. The third brush completes a high speed circuit and enables the wipers to operate at different speeds.
Commutator- the commutator is the rotating part that sits between the brushes and is held in place by the motor shaft. It contains a series of conductive segments separated by insulating strips. The segments conduct current from the brushes to the coil in turns, enabling the continuous rotation of the armature.
Brush plate assembly- the brush plate holds the motor brushes. Other parts of the plate include the springs that tension the brushes and the electric circuit that regulates the power going into the motor.
The wiper motor gearbox is the housing that contains the gears and other parts required by the motor to perform its function. The parts reduce the speed of rotation, multiply torque, and transmit motion to the wiper linkage parts such as wiper arms and rods. The components that make the assembly are:
Worm gear– the end of the wiper motor shaft is a worm, a spiral gear that rotates a gear wheel. Together, the two gears form a worm drive and help to multiply torque through gear reduction. The arrangement also slows down the overall speed of rotation.
Gear Wheel- this is the wiper motor gear that connects to the spiral gear to multiply torque. When the spiral gear rotates, the gear wheel also turns, but at a slower speed. That way, it multiplies the force of rotation to a level enough to move the wiper parts or wiper linkage. Depending on the specific model of the motor, there may be an additional gear or gears.
Parking limit switch- just above the output wheel gear is the wiper park switch consisting of three copper arms attached to the gear box cover. These ride on a conductive ring mounted on a plastic wheel. The wheel, in turn, is attached to and rotates together with the ring gear.
The wiper motor park switch provides power to the motor when you switch off the wipers until the blades move to the park position. This prevents the wipers from stopping on the windshield and obstructing your view when driving.
Gear box cover- this is the removable part that covers the wiper motor gearbox assembly. Apart from protecting the parts inside, the cover also holds parts of the parking limit switch. It also contains the electric connector that supplies power and signals to the electronic components.
Output shaft- the output shaft is attached to the gear mechanism. It helps transmit the wiper motor gear rotation to the outside, thereby helping to move the wiper transmission linkage. In a rear or back wiper motor, the shaft drives the wiping blade directly.
Output arm- the wiper motor arm is the crank that mounts on the output shaft. It connects the parts of a wiper motor to the rest of the system, moving rods and other linkages. The output arm function is to convert the rotary motion of the motor to the linear motion required to operate the wipers.
Connectors- the wiper connectors are electrical wires or components that convey power and electronic signals to the wiper motor assembly parts. It forms part of the wiper motor wiring and is one of the most crucial components. When broken or worn, the motor may not run.
Other parts related to the wiper motor but which are usually not part of its assembly include the wiper fuse, switch, electronic control module and (often), relays.
Wiper fuse- the windshield wiper motor fuse protects the motor components from current overload. It’s usually located in the fuse box. If it blows, the motor stops functioning.
Wiper switch- the wiper switch controls the operation of the wipers by providing a means to switch power on and off. The switch also contains settings for the different wiper motor operations such as different speeds and intermittent wiping.
Wiper control module- this is the circuit board that contains the electronics to govern the motor’s working and, therefore, the entire wiper system. In modern cars, the windshield wiper control module allows the use of technologies such as rain sensors and automated wiper operation. The wiper pulse module, as it is also called, is generally located under the dash.
Wiper relay- the wiper relay switches a large amount of power using the small current signal from the wiper switch. A car wiper system may use up to three different relays; two for the low and high speed circuits and another for the intermittent wiper circuit. The relays are often located in the fuse box, motor, or built into the wiper control module depending on the type of vehicle. Some wipers do not use relays.