What Are Speed Sensitive Wipers?by Mary McNally
Driving in a heavy rainstorm can be a difficult experience when you cannot see through your windshield. You may find yourself constantly adjusting the windshield wiper speed, making them go too fast or not fast enough. The windshield wipers may also start to squeak when you drive through an area where it isn't raining. Speed sensitive wipers, also called rain sensitive or rain-sensing wipers, are a safety feature on newer cars to help with visibility in bad weather.
Windshield wipers have been around for almost a century. They were added as standard safety equipment to most cars in 1916. Drivers had to take one hand off of the steering wheel to manually turn the windshield wipers on and off. Speed sensitive wipers automatically sense when rain, snow or other debris are blocking the windshield and turn on at an optimal speed to keep the windshield clear. Jeep first introduced this technology in 2002 as an option on its Grand Cherokee Limited and Overland.
Speed Sensitive Wiper Technology
An infrared beam on the outer windshield is reflected to an infrared sensor. Moisture buildup and debris interrupt the infrared beam. The amount of rain, snow or debris is calculated by analog and digital signals, and the sensor sends a message to the wiper motor controls to automatically turn on the wipers and adjust them to the correct speed. You can adjust the sensitivity of the system, and it can be turned on or off with one switch.
Speed sensitive wipers turn on automatically when needed, without the necessity of the driver letting go of the steering wheel to turn the wipers on. They automatically adjust their speed to prevent wiper wear and tear, squeaking and glares and streaks that can lessen visibility. Speed sensitive wipers also turn on automatically in the event that the car goes through a large water puddle is or sprayed by passing vehicles.
Wipers that turn on automatically can startle the driver, causing a distraction. Speed sensitive wipers do not work very well in combination with windshield moisture prevention products or when dried salt water or ice buildup is on the windshield. The driver may also have to fumble with a multi-function lever during a rainstorm if the system sensitivity is not set correctly beforehand.
It is a good idea to experiment with the speed sensitive wiper system settings before setting out to drive any distance. You won't have to try to reset the system during low visibility because it will be ready to go and set on the correct sensitivity level. Many speed sensitive wiper systems will need to be turned on again after the vehicle has been turned off and restarted. The Jeep Grand Cherokee rain sensing wipers will not work when the engine is on, the transmission is in "Park" and the outside temperature is subfreezing. This is to prevent damage to the windshield wipers. Put the transmission in "Drive" to enable the rain sensing wipers.
Mary McNally has been writing and editing for over 13 years, including publications at Cornell University Press, Larson Publications and College Athletic Magazines. McNally also wrote and edited career and computer materials for Stanford University and Ithaca College. She holds a master's degree in career development from John F. Kennedy University and a bachelor's degree from Cornell University in counseling.