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Breakaway Kit Installation for Single and Dual Brake Axle Trailers

Breakaway kits are designed to bring trailers safely to a stop by activating the electric brakes should a trailer disconnect from the tow vehicle during transit. Ideally, the safety chains will prevent a trailer from disconnecting if the coupler comes off the ball. However, if the safety chains fail, the breakaway kit acts as a last line of defense against a runaway trailer. This type of safety system is required in most states for trailers weighing more than 3,000 lbs.


The following article will describe how to:

  • Mount a trailer breakaway kit
  • Wire the breakaway kit
    • Details Hopkins, Tekonsha, with and without a charger
  • Attach to a vehicle




The battery box has been mounted to the inside of the trailer frame, adjacent to the trailer connector plug.

Before the breakaway kit installation begins, you will need:

  • Breakaway kit - includes a breakaway switch and a battery contained in a mounting box
  • Electric trailer brakes
  • Connection to the auxiliary power wire from the tow vehicle
    • needed only if the breakaway kit has a charger

Breakaway Kit Components:

  • Breakaway switch - mounted to the trailer frame and has a cable that connects to the vehicle's frame
    • If the trailer disconnects, the cable pulls a pin out of the switch, activating the trailer brakes.
  • Breakaway battery box - houses a 12 volt battery and, in some models, a battery charger




The breakaway switch has been mounted towards the front of the trailer frame, between the rear of the vehicle and the battery box.

Mounting the Breakaway Kit

  • Locate a secure surface on the trailer to mount the breakaway kit battery box.
    • A typical position is on the inside of one of the trailer frames in the front of the trailer.
    • Self-tapping screws or U-bolts are usually included for mounting the battery box.
  • Mount the breakaway switch close to the trailer coupler so the cable can be attached to the vehicle.
    • Also, mount the breakaway switch close enough to the battery box so their wires can connect.
    • A typical position is on the outside of the trailer frame between the trailer connector and the battery box.
    • NOTE: The switch is held in place with only one screw.
      • It needs to be tight but not so tight that it cannot rotate to allow the pin to be pulled out.




Hopkins Diagram

Wiring a Breakaway Kit


Breakaway Kit without a Built-in Charger

  • Breakaway kits without battery chargers require three connections.
    • Remember to periodically remove the battery from the box to charge it, or replace it accordingly.
  • Splice one of the two wires coming out of the breakaway switch into the trailer brake wire running from the trailer connector to the brakes.
  • Connect the second wire coming out of the switch to the brake wire (blue) coming out of the battery box.
    • This connection will send power to the breakaway switch.
    • NOTE: Both wires on the breakaway switch are interchangeable.
  • Splice the white wire coming out of the battery box into the existing ground wire (usually white) running from the trailer connector to the trailer, or screw the white wire directly to the trailer frame.


The first switch wire has been spliced into the blue trailer feed wire.

Hopkins Breakaway Kit with a Built-in Charger

The white wire from the battery charger has been grounded to the trailer frame.
  • Hopkins breakaway kits with built-in chargers require four connections.
    • One connection has already been made inside the battery box.
  • The following diagram shows a typical wiring configuration for a Hopkins breakaway kit with a battery charger.
    • Some other manufacturers have similar configurations, but not all wire colors are the same.
    • Consult your breakaway kit directions before installation to verify the wiring configuration.
  • Splice one of the two wires coming out of the breakaway switch into the trailer brake wire running from the trailer connector to the brakes
    • See point A on the wiring diagram
  • Connect the second wire coming out of the switch to the brake wire (blue) coming out of the battery box.
    • See point B on the wiring diagram
    • This connection will send power to the breakaway switch.
    • NOTE: Both wires on the breakaway switch are interchangeable.
  • Splice the white wire coming out of the battery box into the existing ground wire (usually white) running from the trailer connector to the trailer, or screw the white wire directly to the trailer frame
    • See Point C
  • Splice or run the 12 volt hot lead (black) coming out of the battery box into the 12 volt hot lead running from the trailer connector to the trailer
    • See Point D
    • This connection will charge the battery when the vehicle is in use.




Wiring a Tekonsha or Tow Ready Breakaway Kit with a Built-in Charger


The Six Required Connections:

The first switch wire has been spliced into the blue trailer feed wire.

1. Splice one of the two wires coming out of the breakaway switch into the trailer brake wire running from the trailer connector to the brakes.


The second switch wire has been connected to the positive red post on the battery.

2. Open the battery box and connect the second wire coming out of the switch to the positive post (red) on the battery.

  • This connection will send power to the breakaway switch.
  • NOTE: Both wires on the breakaway switch are interchangeable.

The red and black wires from the charger have been connected to battery.

3. Connect the red wire on the charger to the positive post (red) on the battery.

  • This connection charges the battery.
  • There should now be two wires connected to the positive post: the second switch wire and the red charger wire.
  • Connect the black wire on the charger to the negative post (black) on the battery.

The white wire from the battery charger has been grounded to the trailer frame.

4. Splice the white wire on the charger into the existing ground wire (usually white) running from the trailer connector to the trailer, or screw the white wire directly to the trailer frame.

  • See point C on the wiring diagram shown above

The 12 volt hot lead wire from the charger has been spliced into the trailer 12 volt hot lead.

5. Splice or run the 12 volt hot lead (black for Tekonsha, yellow for Tow Ready) on the charger into the 12 volt hot lead running from the trailer connector to the trailer.

  • See point D on the wiring diagram shown above
  • This connection will charge the battery when the vehicle is in use.




Attaching the Cable to the Tow Vehicle

The breakaway switch cable needs to be secured to the vehicle bumper or frame. The cable can be attached in many different ways. The two most common methods are:

The cable pin has been pulled out of the breakaway switch, activating the trailer brakes. The cable pin is passing through the safety chain pocket and the cable loop on its way back to the switch.

Route the pin through the safety chain loops on the hitch or bumper, then through the cable loop


or


Route the pin through a tow hook, then through the cable loop


Notes:

  • The cable should come straight out from the switch to attach to the vehicle
  • Any angular attachment may cause breakaway switch failure
  • Secure the cable on the same side of the trailer frame as you mount the breakaway switch
  • Do not loop the cable over the hitch ball; the cable may bounce off while the vehicle is moving
  • Before towing, test the breakaway kit by pulling the pin out of the switch to activate the brakes




Mario

12/3/2023

Hi, do these breakaway kits work on a boat trailer? Is the installation waterproof? Thanks.

Etrailer Expert

Jenny N.

12/4/2023

@Mario They will work on boat trailers that have electric brakes. It is weather resistant but not waterproof. Which means that you would not be able to submerge the battery and box in water but it would withstand inclement weather. Ideally your best option would be to mount the battery in a location that is up high enough that it would not get submerged while backing the trailer in the water. Or at least close enough to the coupler that it would not get submerged.

Robert

6/6/2023

So one you pull the pin to test the breaks how do you release the break to get the pin back in

Etrailer Expert

Mike L.

6/6/2023

@Robert When you reinsert the pin, the brakes will release for you. Couldn't be easier! Hope that helps you out.

Robert

6/6/2023

@MikeL the pin broke and i had to buy a new one
Etrailer Expert

Mike L.

6/7/2023

@Robert That's no good! Did you get the pin replaced? Everything working okay now?
See All (5) Replies to Robert ∨

Daryl

5/28/2023

I need some clarification on the idea of using the trailer battery in the wiring scheme for the breakaway switch. I have a wiring terminal block attached to the trailer frame near the hitch. My Curt switch has two blue wires. I would connect one wire to the brakes terminal and the other to the positive feed (red) of the trailer battery which allows for constant 12v power while towing. Why do most instructions call for a separate battery.

Etrailer Expert

Mike L.

5/29/2023

@Daryl You can run your breakaway system using an existing battery if you wish. Breakaway systems include a battery simply because not all trailers are equipped with an auxiliary battery. I'm a fan of using a kit with it's own battery that has a push to test feature, like the Hopkins # 20400. You can check the battery with the push of a button, which isn't possible with a typical trailer battery.

Dave

3/12/2023

I have my brake away switch wired as this. One blue wire tied into my blue brake wire going to brakes. The other wire from brake away going to my distribution box on the trailer that has 12v from my truck. Obviously the brake away switch only works while the truck is still plugged into the trailer. My question is can I run a wire from trailer battery which is just a car battery that I run my winch from to the distribution box stud that has the 12v from the truck or will it back feed into the truck and mess something up?

Medcitymoto

4/8/2023

@Dave I have a deep cycle 12v battery in my trailer hard-wired correctly to the 12v aux line. The truck charges the battery there when driving. No reason another 12v battery tied to the circuit wouldn't be just fine too.
Etrailer Expert

Mike L.

4/8/2023

@Medcitymoto Keep in mind that there are physical limitations for what that 12V circuit can do. The alternator output, the distance between the vehicle battery and the trailer and the small gauge of the wiring will all limit the amount of power delivered to the trailer battery. Keep in mind that the feed can keep a trailer battery topped off, but it won't be able to charge a dead battery.

Zasu

9/11/2022

The wiring diagram for the breakaway w/o a charger was useful enough that I was able to wire mine with the charger but it sure would have been nice to have that diagram included with the instructions for my type. Why include one diagram but not the other?



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