Collision Repair Training | Australia
|
Collision Repair Training | Australia
|
Current Events/News: Advantage Online: 2003 Archives
MOISTURE-SENSING WINDSHIELD WIPERS
May 5, 2003 -Interior rearview mirrors used in vehicles today are housing many different electronic parts including automatic dimming features, outside temperature readings, a compass, airbag status indicators, Global Positioning System (GPS) and telematics system parts, tire pressure monitor indicators and microphones for hands-free phones (see Figure 1). Also included in this list are moisture sensors. Moisture sensors are used with automatic windshield wiper systems and may be original equipment or an aftermarket accessory. Information on these systems is not easy to find. One source is a technical paper written a few years ago by the Society of Automotive Engineers (SAE): "Development of Rain Sensor for Automatic Wiper System." Look for paper #2001-01-0612. An automatic windshield wiper system is considered a safety feature. This is because when the system is activated, the driver is no longer distracted by the constant need to adjust the windshield wipers according to the changing weather condition. These systems are featured on newer model years of vehicles such as the Cadillac DeVille, Pontiac Bonneville, Jaguar X-Type, Land Rover Range Rover and Volvo S80, to name a few. Method Of Operation Moisture-sensing windshield wipers use a moisture sensor and control module to automatically activate the windshield wipers when moisture, such as rain or snow, is detected on the windshield. The intensity of the moisture signals an adjustment to the speed of the windshield wipers. Moisture sensitivity can be controlled based on driver preference.
With one type of automatic system, the moisture sensor and control module are contained in one assembly that is mechanically fastened at the base of the rearview mirror, facing the windshield (see Figure 2). With another type of system, the moisture sensor is mechanically fastened at the base of the rearview mirror and the control module is mounted elsewhere, such as beneath the rear package shelf or the instrument panel. When the system is turned ON, an infrared beam or beams from the optical moisture sensors reflect off the outer glass layer of the windshield at a 45° angle. If the glass is dry, most of the infrared beam is deflected back into the sensor. If there is moisture, the beam is interrupted and deflected in different directions at different rates depending on the intensity of the moisture. The control module uses the amount of deflection to turn the windshield wipers ON and OFF and continually adjust the speed.
On some systems, the automatic system is activated by the delay setting on the windshield wiper switch and deactivated by the HIGH or LOW windshield wiper speed setting. On other systems, there may be an actual AUTOMATIC setting on the windshield wiper switch (see Figure 3). Inspecting The System Since the moisture sensor and control module are hidden from view, it may be difficult to determine if a vehicle is equipped with a moisture-sensing windshield wiper system. One of the indicators is a larger-than-normal housing at the base of the rearview mirror. However, the rearview mirror mount can also house other sensor-activated systems or a navigation system. There may be an indication on the windshield wiper switch of an automatic setting. If available, the system may be identified in the vehicle owner's manual. Otherwise, the only way to determine if there is an automatic wiper system on-board may be to physically operate the system during the post-repair inspection. When performing a post-repair inspection, if the windshield wipers operate at the HIGH and LOW speeds, but not in the INTERMEDIATE setting, apply water to the windshield, start the vehicle and shift to DRIVE. If the windshield wipers operate, then the system is in good working condition. If they do not operate, either the automatic feature is inoperative or the delay feature is inoperative and further testing is required. Typically, a DVOM is used to make voltage and resistance checks according to a flowchart provided by the vehicle maker. At least one system requires a scan tool to test the sensor and control module for proper operation. If the moisture sensor or control module is damaged, it should be replaced. Typically, if the wiring is damaged, it can be repaired using general wiring repair guidelines and waterproof connectors. |
||||||||||||||
|
||||||||||||||
|
Page Last Revised: |
||||||||||||||
