Car windscreen wipers rely on a component called wiper motor to work. Hidden under the hood, the motor provides the torque to move the wipers. Its action ensures your car windscreen is free from mud, dust, and rainwater when on the road. But what is a wiper motor and how does it work? This guide has the answers and a lot more, starting with the definition.
All there is to know about Automotive Wiper motors
Wiper Motor Definition
The car wiper motor is the electrical device that rotates to operate windscreen wipers. It’s usually a simple DC motor with brushes (or without), and copper wire armature. The motor is also called windshield wiper motor or windscreen wiper motor.
Wiper motors form part of the windscreen washer system that comprises a wiper switch, wiper linkage, wiper arms, and the wash fluid reservoir. It’s usually located in the engine bay where it mounts on the firewall using bolts.
Most vehicles use a single motor for the front windshield. Others come with a rear wiper motor as well, with high-end cars featuring rear window wipers. Every extra windshield or window to be wiped means an additional motor. A vehicle may, therefore, have the component in other places than the front windscreen.
Wiper motor design varies. One version of the motor uses permanent magnets, the other electromagnets. You can easily recognize a permanent magnet type of motor by its shape. It’s normally a cylindrical shape compared to the square shape of those that use electromagnets.
There’s also the one speed and variable speed wiper motor. These mostly differ in the number of brushes. The single-speed motor uses two brushes, the two-speed type three. Now, on to the wiper motor working principle and, why you need it functional in your car.
Wiper Motor Function and Operation
The wiper motor is the engine behind the operation of windscreen wipers. It provides the torque to move them, ensuring a clean windshield. The motor is located in a convenient place that allows it to work the wiper mechanism.
The wiper motor location aside, its design also helps to increase effectiveness. The setup consists of transmission gears. The arrangement of the gears multiplies the rotational force of the motor in what’s called gear reduction. The operation happens as follows.
- When you switch on the windscreen wipers, the switch sends the signal to the electronic control model located on the wiper motor transmission assembly
- The control model operates several circuits, including the relay that sends voltage to the motor itself
- The motor contains a wire winding which, on being energized, produces a reaction force that causes the armature to start spinning
- The spinning armature rotates a shaft. The shaft contains a worm or spiral gear
- The spinning worm rotates a toothed plastic wheel which, in turn, operates pinion gear. The gear rotation works a short arm or pushrod into to and fro motion
- The arm is connected to the wiper linkage. Its back a and forth movement operates the linkage arms which then move the wiper blades against the windscreen surface
Some wipers activate automatically when it starts to rain. The action is controlled by the motor’s electronic module and requires the input of rain sensors. The sensors are installed on the windscreen.
Wiper motors also operate on a “safe park” circuit. The circuit allows the wiper blades to reach their rest position even when you switch off the wiper system when they are midway on the windscreen.
Parts of Wiper Motor and Transmission Assembly
To move the wipers, the motor uses a transmission mechanism consisting of a set of gears and electronics. The setup is the mechanism behind the back and forth motion of the wiper blades. To help you understand the assembly in more detail, here are the main parts that make it.
The wiper motor, as we have seen, is usually the traditional direct current motor. It consists of a steel housing enclosing several components. Main wiper motor parts include permanent magnet, armature, brushes, and shaft. These components work together to produce rotation.
The magnet provides the magnetic field that causes the motor to spin. It can be permanent or electromagnetic. The armature is the rotating piece and comprises copper wire winding around a magnetic core.
The brushes are conductors that act as pathways for electric current to flow into the armature coil. A wiper motor usually has three brushes. The third brush allows for two different speeds, high and low depending on the circuitry.
The wiper motor shaft is the central rod that runs through the motor and on a bearing at each end. It holds the armature, allowing it to spin freely when the motor is in operation. The shaft contains a worm on the side of the transmission. As it rotates, the worm gear spins a larger wheel connected to it.
Connected to the wiper motor is the drive mechanism. The mechanism uses the motor rotation to work the wiper system. It consists of a housing toothed plastic gear, wheel containing a conductive ring. There are also often pinion gears to increase the efficiency of the setup.
The toothed gear or wheel meshes the worm gear on the motor shaft. As the shaft spins, the gear also rotates. The gear is joined with another plastic wheel that rotates along with it. On the wheel surface is a conductive ring that helps to ensure the wipers stop at their resting place when you switch off the wiper motor power.
The worm on the motor shaft works together with the larger to provide gear reduction. This enables the motor to produce a large torque capable of operating the heavy linkage and wiper arms. The arrangement also reduces the speed of rotation to a level that suits the action of the wipers.
Electronic Control Module
This the electronic part of the assembly. It contains the electronic circuits and components to operate the setup. The module ensures the right inputs are fed to particular parts such as the motor and “wiper parking” circuits.
The wiper motor controller is a board that mounts to the inside surface of the housing. It receives the electrical connectors to the assembly. These include power connections and those that bring various signals.
A functional module means a functional wiper motor mechanism. If damaged, you may experience problems with the entire system. Movements may turn sluggish or you may have the system develop issues now and then, as explained next.
Common Wiper Motor Problems
The wiper motor is both mechanical and electrical. It contains moving parts that wear with time and electronic components that may fail unexpectedly. The motor is also exposed to the heat in the engine bay and atmospheric moisture and dust.
Problems with the motor affect the entire system, including the transmission and linkage. Issues may show as a slow motor rotation, intermittent stops, or total failure. Here is a summary of common problems, their cause, and how they affect the motor and related parts.
Bad or loose wiper motor connector
Bad connections reduce the amount of current reaching the motor or cut it off completely. Loose connections also cause intermittent and unpredictable problems with the motor such as stopping unexpectedly while the wipers are wiping the windshield.
Blown wiper motor fuse or relay
A bad wiper motor relay or fuse leads to power problems that result in the motor not rotating. A test would help confirm if the specific part is damaged. A fuse or relay can be replaced, even by the car owner.
Worn wiper motor brushes
The motor brushes wear down with time. You cannot prevent that. However, they are replaceable parts that also do not cost a lot. It’s recommended that you change the brushes when they are broken.
Worn or broken wiper motor gear
The gears that are part of the wiper motor and transmission can get worn or damaged. Because the gears transfer the motor rotation to the wiper linkages and arms, their failure means the entire system not working. The gears are replaceable.
Bad wiper motor module
The module is also called the wiper motor controller and contains the circuit that controls its operation. If damaged, the motor may start to work abnormally, leading to a failed wiper system. Electrical tests can help reveal if the module is not working.
Clogged wiper motor parts
A buildup of debris inside the wiper motor or transmission system also causes problems. Clogged parts rotate slowly or do not rotate at all. Clogging also puts a strain on the motor, which may even burn out. Debris affects electrical connections, too, leading to some parts of the wiper motor not working.
Wiper motor troubleshooting requires the help of a mechanic, although DIYers can do it with the right tools and equipment. Diagnosis includes performing tests on the motor itself and supporting components such as fuses and relays. These are mostly electrical tests.
Besides the wiper motor test or tests, a physical examination helps to assess damage and identify the source of problem and fix it. It’s easy to notice clogged gear systems and buildup inside the motor housing. Broken or worn components such as gears and brushes, too.
Wiper Motor FAQs
Q1. What is the RPM of a wiper motor?
A. The wiper motor rpm is usually for 45 rpm for normal speed and around 65 rpm when on the fast speed settings. It also comes in 6V, 12V, and 24V configurations. The typical wiper motor uses a current of between 2 and 4 amperes. Most wiper systems allow for two-speed settings for the wipers. In such setups, the motor uses three brushes instead of two.
Q2. What does a wiper motor pulse board module do?
A. The module is the board that contains the electronic control circuits of the wiper system. It determines various actions, including speed settings, wiper parking, and turning the wiping mechanism and off. In short, it determines the operation of the wiper motor and linkage. The module can get damaged, despite it being protected from the harsh conditions of the engine bay. Luckily, it’s a replaceable part.
Q3. Why does a wiper motor need a relay?
A. The relay switches on a much larger current for the motor using a smaller current. Some motors use a relay while others do not. Usually, the wiper motor current rating determines if a relay is needed or not. Higher rated motors require one, while low power types do not. If you have a rear windshield wiper, its motor is likely to be using a relay.
Q4. How long should a windshield wiper motor last?
A. Wiper motors are meant to last a long time, as long as the lifetime of your car. However, that does not always happen. The component tends to break down earlier depending in usage and operating conditions.
If you have to use the windscreen wipers every day, the motor is likely to be worn after only a few years. Electrical faults can also shorten the lifespan if a wiper motor causing it to burn out. Poor maintenance of the wiper linkage, too, which causes a strain on the motor. To increase the wiper motor lifespan, here are useful tips
- Ensure regular maintenance such as applying lubrication to the moving parts of the linkage and replacing worn components
- Always unstick the wiper blades that have not been used for some time manually
- Avoid using frozen wiper blades to prevent instances where you stress the motor
- Always ensure the wipers are in their correct parking position when not in use. They will not stress the motor when starting
- Make a habit of switching off the wipers before the engine so they return to park correctly
Q5. What are the signs of bad car wiper motor?
A. Wiper motors contain both mechanical and electrical parts. These cause different symptoms when damaged or worn. With a keen eye, you can easily pick out the signs. Here is how to tell if a windshield wiper motor is bad.
- The wipers are not moving when you switch them on
- wipers not stopping when you want them to
- The wipers are moving slower than usual
- You cannot change wiper settings such as moving to a higher speed
- Grinding or clunking wiper motor noise
- Wipers not “parking” or returning to the furthest bottom of the windshield when you switch them off
Most of the signs are caused by a worn motor that need replacing or damaged individual components that can be changed. Clogging is also another reason why you’re seeing the bad wiper motor symptoms.
Q6. Are wiper motor repairs possible?
A. They are, depending on the nature of damage. Worn brushes can be replaced or the armature rewound. Other replaceable parts include the gears in the motors transmission setup. Cleaning a clogged wiper motor or its transmission assembly restores its function without even replacing it. Many people do not repair wiper motors. Instead, they replace the entire system.
Q7. What is the range of car wiper motor price?
A. Wiper motor cost varies from one manufacturer to another and ranges from $60 to $300. The amount can be less or higher depending on the type of motor or model and the vehicle it’s meant for. Different wiper motor suppliers will also have different price tags for the same product. When looking to buy your replacement motor, we would advise you to compare the prices of different suppliers.
Q8. What’s the average wiper motor replacement cost?
A. You can expect to pay between $$50 and $100 for the wiper motor replacement job. That is excluding the cost to purchase the component, varies from $50 to $300 for most models. Should you choose to do it yourself, ensure you have the instructions for the procedure. Wiper motor replacement instructions usually come included in the product package.
Q9. Can I replace a wiper motor myself?
A. The wiper motor location makes the task somewhat difficult. There are several components to remove and, and you need to have an idea about the procedure. You also need the right tools. If you have both the knowledge and installing equipment, a DIY job can save you about $100. Having said that, it’s always advisable to have a mechanic do the work.
Q10. How do I buy a windscreen wiper motor?
A. Wiper motors are built for specific makes of cars. You, therefore need to have information about your type of vehicle when shopping for the component. Your car manual will also have details of the wiper motor specifications to look for.
Other than the wiper motor specs, there’s the choice between an OEM motor or aftermarket model. Both types will fit your vehicle. However, aftermarket options offer flexibility in terms of features and price. You can find one with higher capabilities but selling at a much lower price that an OEM type.
Wiper motors come as single component or kit. A wiper motor kit contains other parts of the wiper system such as arms, blades, and mounting hardware. When shopping for the component, it’s necessary to decide the kind of product you want.
The windshield wiper motor ensures you have clear vision when driving. It provides the mechanical energy to move the entire system that comprises arms and blades. Wiper motors, although designed to last a lifetime, can break down and fail. When that happens, you want to be able to find a replacement. You also want to know when you have a failed wiper motor so you can take action early enough. The information contained in this article is meant to help you with all that and more.