What to Use to Control the Variable for a 12V Wiper Motorby Donna McLean
You depend on your windshield wipers to clear moisture from the outside surface of your vehicle. Variable speed and intermittent wiper cycles allow you to adjust the wipers to give you the best vision possible in stormy weather. When you turn the control knob or flip the switch, current flows from the battery through a module or through connectors that are wired to the motor. The setting you choose determines the speed and interval at which the motor turns. Besides controlling windshield wipers, you can use a 12-volt wiper motor and variable-speed control to provide movement for decorations and props.
If your motor is a two-speed motor, you can install a simple switch that allows you to set the wiper speed to low or high, as well as to set the wipers to “Off.” “Off” sometimes is called “Park” because this setting allows the wipers to slowly return to their original position before they stop. Choose a switch that is compatible with the motor and the vehicle. Some have connections to control the windshield washer, as well as the wiper speeds, and not all switches are interchangeable.
Intermittent Wiper Control
Use an intermittent wiper control module if you want to be able to set the wipers to come on at intervals. Intermittent wiper controls in the 1970s routed power through a series of switches. More recent vehicles use microprocessors, also known as integrated electronic modules. Such a module also may be labeled “Module, Timing.” In GMC vehicles, it is known as a “pulse board” or “circuit board.” One type of module, the MGA Wiper Control, can be connected to the wiper system already in your vehicle simply by joining a few wires and mounting the module and control knob on the vehicle dashboard. Look for a module that is compatible with both the 12-volt wiper motor and the vehicle in which it will be installed.
You can buy combination control levers that mount on the side of your automobile’s steering wheel. These controls can be custom-made to fit your requirements. You can choose to have them control wiper speeds and turn signals, as well as the headlights, or they can be built to serve a single function.
Rain-sensing systems have infrared optical sensors that detect light interference from raindrops falling on the windshield. The microprocessor turns on or adjusts the speed of the wipers according to information it receives from the sensors. You can override the system when needed, such as when you drive through an automatic car wash. You can install some types of rain-sensing systems by connecting them to the existing variable-speed wiper control in your automobile.
Wiper Control Kits
Use your 12-volt wiper motor and a wiper control kit to rig decorations and props so they move at intervals. For example, connect ghostly figures to strings attached to the motor gear lever to create Halloween spooks. Choose a control kit with all parts needed to make a control board or buy a kit already assembled.
If you buy a wiper motor assembly, it should include the motor, gear and linkage. The control is sold separately. To find compatible controls that are reasonably priced, check with your local automobile salvage yard.
Donna McLean began writing in 1967 with an article published in the newsletter of her alma mater, Montana State University. Her articles have since appeared in a variety of publications including the “Philipsburg Mail,” “Ghost Town Quarterly” magazine and the association newsletter “Connections.”