by Jim Kerr

Every vehicle has them. Some have one; most have two, and there are even some with three! Wipers are an important safety feature on our vehicles but they usually only get any attention when they don’t work. With spring showers on the way, your vehicle’s wipers will be put to the test again. Inspecting them only takes a few seconds.

Rubber wiper blades don’t last forever. After a few years, the rubber starts to tear and then you have a metal wiper arm rubbing against the windshield. Unfortunately, this usually happens when you are driving down the highway far away from any service shop and an expensive windshield gets scratched. Replace the rubber blades before problems occur. I find that after about two years of service, the rubber is starting to harden enough that wiping performance decreases. Installing new blades takes a few minutes and can be done by most owners.

The lowest cost wiper blade is typically a wiper blade “refill”. This is just the rubber blade with some thin stainless reinforcement strips. The old blade insert is removed from the wiper arm by squeezing the sides together and slipping the insert out the end of the wiper arm. Installing the new refills is the opposite of removing the old ones. Wiper blades come in many different lengths so be sure to measure yours before going into the parts store.

A quicker and easier method (but more costly) way of replacing the blades is to replace the wiper blade complete with it’s support mechanism. Usually the complete unit unclips from the wiper arm and can be removed in a couple seconds. There are several options when buying new units. Some come completely encased in rubber to prevent ice build-up in the pivot points. Others have wings on them so the wind will push the wiper blades down on the window glass at high speed. Some come with two blades in one, for improved clearing in heavy rain. Silicone rubber is used in some blades so they are more flexible. All work well but the most important thing to remember is that any blade needs regular replacement.

Electronics are changing the way wipers work too. Almost all vehicles now come with intermittent or pulse wipers. Capacitors inside the wiper motor charge up electrically until the voltage is high enough to trigger a transistor. The transistor turns on the wiper motor for one sweep. The driver controls the delay time or pulse rate with a knob that varies the voltage to the pulse circuit in the wiper motor. It sounds complicated but it is really a very simple electronic circuit.

Sometimes a vehicle will have a “phantom” wipe. The wiper motor makes one sweep all by itself without the driver even touching the wiper switch. Usually this problem is caused by moisture on the pulse circuit board in the wiper motor. Water is a conductor of electricity so a drop in the wrong place can cause unwanted operation. A trickle of electricity flows through the water from a power connection to a pulse input connection and the wipers turn on. Often this problem occurs after the vehicle’s engine compartment has been thoroughly washed at a hand-operated car wash. Sealing the electrical connections with some silicone grease can help prevent water from entering.

Improvements to wipers aren’t dramatic but do occur. Rain Sense wipers are now offered on several premium and luxury vehicles. A module near the interior rear view mirror detects the change in refraction of light as it passes through water on the windshield. The driver sets the wipers in Auto mode and forgets them. When water is sensed, the wipers turn on automatically until the windshield is clean again. This system is great when driving in a slight mist where even the slowest pulse setting is too frequent. The rain sense system only operates when there is moisture present, but be sure to remember and turn them off before entering an automatic car wash!

Finally, an Ontario inventor has designed a wiper shaker. How many times have you had the wiper blades freeze up in the winter and clear only a small part of the windshield? The wiper shaker vibrates the wiper arms and blades, causing the ice to break off the wipers. It’s much easier and safer than stopping the car and clearing them by hand.

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