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WHR1 Wiper Motor / Horn Reducer Installation Instructions

Click here to download the full guide with images

This device is designed to reduce the voltage to power a 6 volt wiper motor or horn after conversion of the vehicle electrical system to 12 volts.

Step 1. Disconnect the battery from the vehicle. Always do this step as you don’t want to be working with your electrical system while the battery is connected. Never skip this step.

Step 2. Mount the resistor using the enclosed #4 x 3/8” sheet metal screws. For best and safest results, mount this resistor on a metal surface away from materials that may melt, such as plastics, and away from passengers. The resistor develops heat as a byproduct of reducing voltage.

Step 3. Using the enclosed blue terminals and wire, connect one end of the resistor to the horn or wiper motor.

Step 4. Connect the other end of the resistor to the horn relay H terminal or wiper switch output. This is a series or in-line connection. There is no polarity to this dropping resistor; you can connect either end to the horn or wiper motor, and it is not sensitive to positive or negative ground.

Step 5. Check your work to make sure the wires are not touching moving parts such as wiper linkages and that the resistor is not touching anything that could melt, and is mounted in a location away from passengers.

Step 6. Reconnect your battery.

Step 7. Turn on your wiper motor or horn and check the voltage between chassis and the wiper motor or horn while it is running. Voltage output from the resistor should be about 6 - 8 volts.

A common question is, “Why am I getting 12 volts on both ends of the resistor when not connected to the wiper motor or horn, or when the wiper or horn is not turned on?” The answer is that this reducer requires a load to drop the voltage, so the measurement must be made when the horn or wiper motor is connected and on.

The WHR1 is only designed for use with a horn or a wiper motor. To supply 6 volt power to both a horn and wiper motor, you will need a WHR1 for each. For other applications, use these products:

  • Oil, Gas, or Temperature Gauges: V12872 or VREG06703
  • Heater Blower Motor: HR01
  • Tube Radio: DR100W1R5
  • Power Windows, Seats, Convertible Top: VRWTS
  • Borg Warner Overdrive Solenoid: VRODS1

Vintage Auto Garage cannot be held responsible for wiper motors or horns damaged by using this device. Proper installation and voltage after installation is the responsibility of the end user. 90 day warranty is limited to the resistor itself. This is the only warranty express or implied. Not responsible for any consequential damage caused by this device.

Always be safe and disconnect your battery when working on your electrical system!!

Click here to download the full guide with images