How To Use Rear Windshield Wiper

Rear windshield wipers, often an afterthought for many drivers, are a crucial safety feature, particularly in inclement weather or on vehicles prone to accumulating dirt and grime on the rear window. This article provides an in-depth guide to understanding, using, and maintaining your rear windshield wiper system, ensuring optimal visibility and safety when you need it most.

Background: The Evolution of Rear Wipers

While front windshield wipers have been a standard automotive feature for over a century, rear wipers are a relatively newer addition. They became more prevalent as hatchbacks, SUVs, and station wagons gained popularity. The aerodynamics of these vehicles often result in increased turbulence and accumulation of dirt and water on the rear window, significantly impairing the driver's rearward visibility. This is because the airflow separates from the vehicle's roof and back, creating a low-pressure zone that sucks up road spray and debris. Therefore, rear wipers were designed to combat this problem and enhance driver safety.

Initially, rear wipers were relatively simple, often using a basic single-speed motor and a rudimentary wiper arm. Over time, they have evolved to include features such as intermittent wiping modes, integrated washer nozzles, and even automatic activation linked to rain sensors or when reverse gear is engaged (especially on certain models with parking assist features). The motors themselves have become more efficient and reliable, and the wiper blades are now available in various materials and designs to improve wiping performance and durability.

Technical Breakdown: How Your Rear Wiper Works

The rear windshield wiper system, while seemingly simple, consists of several interconnected components working in harmony. Understanding how these components function is key to troubleshooting problems and performing maintenance effectively.

Components of the System

• Wiper Motor: The heart of the system, the wiper motor is typically a small DC (Direct Current) motor. It's responsible for converting electrical energy into the mechanical motion needed to move the wiper arm. These motors are designed for relatively low speed and high torque, necessary to overcome friction and the resistance of water and debris on the glass. Modern rear wiper motors often include an internal gearbox to further reduce the motor's RPM and increase torque.
• Wiper Arm and Blade: The wiper arm connects the motor's output shaft to the wiper blade. It provides the necessary leverage and pressure to ensure the blade makes consistent contact with the glass. The wiper blade itself is usually made of rubber or silicone and is designed to effectively remove water, dirt, and debris from the windshield. The blade's design, including its profile and the type of rubber used, greatly affects its cleaning performance and longevity.
• Linkage: The linkage system, comprised of metal rods and joints, translates the rotary motion of the motor into the back-and-forth (oscillating) movement of the wiper arm. This linkage is often located inside the rear hatch or tailgate. Proper lubrication of these linkages is critical for smooth operation and preventing excessive wear.
• Washer Nozzle and Pump: Many rear wiper systems incorporate a washer nozzle that sprays washer fluid onto the rear window. The fluid helps to loosen dirt and grime, making it easier for the wiper blade to clean the surface. A small electric pump, usually located in the washer fluid reservoir, provides the necessary pressure to deliver the fluid to the nozzle. The nozzle itself can be adjustable, allowing you to aim the spray for optimal coverage.
• Wiring and Control System: The entire system is controlled by the vehicle's electrical system. A switch or stalk on the steering column activates the wiper motor and washer pump. The wiring harness provides the necessary power and control signals to the various components. On newer vehicles, the rear wiper may be integrated into the vehicle's computer system, allowing for features like automatic activation in reverse or integration with rain sensors.

How it Works: Step-by-Step

1. Activation: When you activate the rear wiper switch, you complete an electrical circuit, sending power to the wiper motor.
2. Motor Operation: The wiper motor begins to rotate, driven by the flow of DC current. The internal gearbox reduces the motor's speed and increases its torque.
3. Linkage Movement: The rotary motion of the motor is converted into oscillating motion by the linkage system.
4. Wiper Arm Movement: The linkage system drives the wiper arm back and forth across the rear windshield, clearing water and debris.
5. Washer Function (if activated): If you also activate the washer function, the washer pump draws fluid from the reservoir and sends it through the hose to the washer nozzle. The nozzle sprays the fluid onto the windshield, loosening dirt and grime.
6. Cleaning Action: The wiper blade then wipes the fluid and loosened debris away, providing a clear view through the rear window.

Common Issues and Maintenance Concerns

Like any mechanical system, the rear windshield wiper can experience problems over time. Regular maintenance and prompt attention to issues can prevent more serious and costly repairs.

• Wiper Blade Wear: The wiper blade is the most frequently replaced component. Over time, the rubber degrades due to exposure to sunlight, ozone, and temperature fluctuations. Signs of wear include streaking, skipping, and chattering. Replace your wiper blades every 6-12 months, or sooner if you notice these issues.
• Motor Failure: The wiper motor can fail due to overheating, water damage, or worn-out brushes. Symptoms of motor failure include the wiper not working at all, moving slowly, or making unusual noises. Replacing the motor is usually the best course of action.
• Linkage Problems: The linkage can become stiff or seized due to lack of lubrication or corrosion. This can cause the wiper arm to move erratically or not at all. Lubricating the linkage with a suitable grease can often resolve the problem. In severe cases, the linkage may need to be replaced.
• Washer System Issues: The washer system can experience problems such as a clogged nozzle, a faulty pump, or a leak in the hose. A clogged nozzle can be cleaned with a small pin or needle. A faulty pump will need to be replaced. Leaks in the hose can be repaired with hose clamps or by replacing the damaged section of hose. Ensure that the washer fluid reservoir is filled with a suitable washer fluid, especially in colder climates to prevent freezing and damage to the system.
• Electrical Problems: Wiring faults, blown fuses, or a faulty switch can also cause the rear wiper to malfunction. Check the fuse for the rear wiper circuit first. If the fuse is blown, replace it with one of the same amperage rating. If the fuse blows again immediately, there is likely a short circuit in the wiring. Use a multimeter to check for continuity in the wiring and to verify that the switch is functioning correctly.

Do's and Don'ts / Best Practices

To ensure the longevity and proper functioning of your rear windshield wiper, follow these do's and don'ts:

Do's

• Regularly Inspect Wiper Blades: Check your wiper blades for wear and tear at least twice a year.
• Keep the Windshield Clean: Regularly wash your rear windshield to remove dirt and debris that can accelerate wiper blade wear.
• Use Washer Fluid: Always use a proper washer fluid in the reservoir. Plain water can freeze and damage the system.
• Lubricate the Linkage: Periodically lubricate the wiper linkage to prevent stiffness and corrosion.
• Replace Blades Promptly: Replace worn wiper blades as soon as you notice streaking or other signs of wear.

Don'ts

• Run Dry Wipers: Never operate the wipers on a dry windshield. This can damage the wiper blades and scratch the glass.
• Use Abrasive Cleaners: Avoid using abrasive cleaners on the windshield, as these can damage the glass and wiper blades.
• Force Frozen Wipers: Do not force frozen wipers to move. Allow them to thaw before using them.
• Ignore Unusual Noises: Pay attention to any unusual noises coming from the wiper motor or linkage, as these can indicate a problem.

Conclusion

The rear windshield wiper, though often overlooked, is a vital safety component, especially on vehicles with limited rear visibility. By understanding how the system works, performing regular maintenance, and addressing issues promptly, you can ensure that your rear wiper provides optimal performance and contributes to a safer driving experience. Prioritize regular blade checks and replacement, and don't hesitate to consult a qualified mechanic if you encounter more complex problems. Remember, clear rearward visibility is just as important as a clear view ahead.