What Is a Winch Solenoid?

Lori Kilchermann
Lori Kilchermann
Woman holding a book
Woman holding a book

The winch solenoid is an electronic device used to activate the winch motor on a vehicle-mounted winch. Created to withstand the high draw of electricity required to crank the winch, the winch solenoid is designed to supply the required current without damaging the winch switch or the winch motor. The winch solenoid is an electromagnetic switch that is activated when current from the battery is directed to the solenoid by pressing the activation switch. The activation of the solenoid sends current to the winch motor and the motor begins to turn the winch drum. The typical winch uses separate solenoids for forward and reverse, with the strongest winches using four solenoids.

The electric, vehicle-mounted winch motor is nothing more than the same engine starter motor used on many vehicle engines. Like the starter that is used to crank a vehicle's engine, the winch motor requires the use of a solenoid to send the proper amount of current to the motor. A common winch uses a separate winch solenoid to move the winch drum in and out. On the strongest winches, which is commonly series-wound, has a four-winch solenoid arrangement and is commonly used with two solenoids working in unison for both winch directions.

Depending on the winch manufacturer as well as the winch style, the winch solenoid can be either mounted on the winch or in a remote location. When mounted on the winch, the winch solenoid is commonly mounted above the winch motor. This eliminates extra wiring and reduces the opportunities for chaffing a wire and creating a short in the winch's electrical system. Remote-mounted solenoids, while more complicated, protect the solenoids from excessive heat created by the winch motor. This can often save the winch from shutting off in the midst of a pull due to the overheating of the winch solenoid.

Another plus to having remote-mounted solenoid switches on any winch is space savings. By removing the winch solenoid from the top of the winch motor, the winch becomes a smaller package and requires less room to mount. A smaller winch is more easily hidden behind a bumper or brush guard, and is also more easily protected from damage. Many winch failures are directly related to damage incurred while traveling on trails and encountering rocks, tree limbs and other debris that damages the solenoid. Protecting the solenoid allows the winch to be relied on and operational when use is required.

How To Wire a Winch Without a Solenoid

It helps to have some general knowledge of DC wiring before attempting this. With an idea of how the electrical system works and a few common tools, you should be able to get around the solenoid with no problem.

The solenoid is a high-current switch. When you send a small-wire signal with battery voltage (usually 12 Volts) to the small-wire terminal on the solenoid, it completes a small-wire circuit that energizes the electromagnetic coil inside. This energized coil pulls a piece of metal against a spring in a short-travel, in-out plunger motion. When the piece of metal is pulled into position, it completes the big-wire circuit.

With the big-wire circuit complete, current immediately flows from the battery through the solenoid metal piece, down the big wire and ends at the winch motor terminal. Keep in mind the solenoid metal piece has to be thick enough to carry current like the big wires. Some winches have multiple solenoids which can control each direction separately.

In some instances, it may be necessary for you to bypass the solenoid within the winch electrical system:

  • Troubleshooting the Winch
  • Custom Build Project
  • Relocating Solenoid/Winch Drum
  • Remote Switch Issue
  • Vehicle-Related Issue
  • Battery/Alternator or Wiring Issue

Whatever your reason for bypassing the solenoid, here's a general walkthrough to help you out:

Tools Needed

  • Jumper Cables or Length of Thick Wire and Clips
  • Screwdriver or Nut Driver (for dust covers)
  • Needle-nose Pliers 
  • Protective Eyewear
  • Fire Extinguisher
  1. Locate the solenoid(s). Remove the dust cover if necessary to gain access to the wiring terminals.
  2. Find the big-wire terminal that is colored red and says "+ Battery". It should test positive for battery voltage at all times, even if the vehicle is off.
  3. Attach one end of a red jumper cable to the red "+ Battery" terminal.
  4. Attach the other end of the red jumper cable to the desired function terminal. If the terminals aren't labeled, test them for direction by touching the jumper cable to each terminal for only a second to see which way the winch spins.
  5. Remove either end of the red jumper cables to stop the winch.

How To Replace a Winch Solenoid

After you've investigated the problem and determined the solenoid to be faulty, it may be time to replace the unit. Your vendor may ask for the core return, so hang on to the broken solenoid once it's removed. Once you receive the new solenoid, place it next to the old one to compare the sizes and shapes. They should be identical.

  1. Remove the wire at the vehicle's negative battery terminal.
  2. Loosen the terminals on the old solenoid and remove the wires. Be sure to remember where they all go back.
  3. Unscrew or unbolt the fasteners holding the solenoid in place.
  4. Remove the old solenoid.
  5. Mount and fasten the new solenoid.
  6. Replace the wires to the proper terminals.
  7. Replace the negative wire on the vehicle's battery terminal.

How To Test a Winch Solenoid

To test the solenoid's electrical system, you will need a voltmeter. Check for battery voltage at the red "+ Battery" big-wire terminal on the solenoid. It should show battery voltage even if the vehicle is off.

With everything off, check for voltage at the other big-wire terminals on the solenoid. They should all be zero.

Choose a direction to spin the winch. Spin it while checking for voltage at the big-wire terminal that should correspond with that direction. It should show battery voltage only when the solenoid is engaged for that particular direction of spin.

If you press the button to engage the spin, but it doesn't spin and there's also no audible click sound, then something is wrong with the solenoid. Solenoids click loudly when they are operating correctly.

How To Quickly Double a Winch's Pulling Force

By using a pulley or snatch block, any winch can be made twice as strong in minutes. A snatch block is just a pully that opens at its side. Instead of pulling a vehicle out of the mud by attaching the winch directly to the stuck vehicle's tow hook, adding a snatch block to the mix requires a little bit different arrangement.

This time, anchor the snatch block to the stuck vehicle's tow hook. Run your winch out twice the length required to touch the stuck vehicle. Return the winch end back to the towing vehicle's frame and attach it. Run the winch cable through the open snatch block and shut it closed. Now, when the winch pulls, it will remove the slack in the cable and spin the snatch block. Once tension is met, there now exist two parallel cables pulling the stuck vehicle.

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