Diagram Showing How Trailer Brakes are Wired

Question

Question:

when you wire tandem axles, do you do it in series or parallel ? how about a diagram ?

asked by: phil

0

Expert Reply:

The brake wire providing voltage is wired in parallel, with one lead from each magnet being grounded to the trailer frame.

We have a great Wiring Help Page that shows a diagram, I will provide a link to it below.

expert reply by: Mike L

0

Ed C.

6/30/2025

Just got electric brake setup to replace hydraulics. New backing plate with complete setup shoes, magnets etc. I also got the breakaway switch., new 7 pin cord, and wire for trailer. Now :…. How do I wire the whole thing up? Ed

Reply

Mike L.

7/2/2025

@EdC I highly recommend running your trailer's 7-way whip into a junction box like # 3375601100. This provides an organized and clean place to make all your connections so they're protected from the elements. I don't know which whip you have, but be aware that the color coding of the wires in the whip might be different than those of the trailer. Each brake assembly will ground to the trailer frame, with the other wire carrying voltage from the brake controller. Join those into a single lead running to the trailer tongue where you'll install the junction box. The brake output circuit from the vehicle (usually a blue wire) will install on the same junction box terminal as the wire you ran forward from the brakes. I'll link you to a help article that explains this, there are some really nice, easy to understand wiring diagrams that I hope you'll find helpful. I'll also link to an install video for the junction box.

Helpful Links

faq-wiring.aspx

tv-review-buyers-trailer-junction-box-3375601100.aspx

Reply

Ed

7/2/2025

@MikeL thank you.

Reply

Ed C.

7/2/2025

@Ed thanks Mike can you talk to ma about the breakaway box wiring up? How’s that work?

Reply

See All (7) Replies to Ed C. ∨

Answer 1

It sounds like you are speaking of the wires for the brake magnets. If this is correct, you will need to connect one of the wires to the brake controller output wire on your trailer connector and the other wire will need to be grounded to a clean…

view full answer...

Answer 2

Hey Byron. The 24-7/8" Long 6-Leaf Double-Eye Spring item #e64SR is going to be the correct one so long as your leaf springs are or near 24-7/8" long from the center to center of the eye bolts. I can't identify the correct replacement…

view full answer...

Answer 3

There are Retrax XRs for your 2020 Ford F-250 Super Duty which have rails that will allow you to install a rack system to carry four of the Yakima FrontLoader Wheel Mount Bike Carrier #Y02103. The correct Retrax XR tonneau cover will depend on the…

view full answer...

Answer 4

Hey Greg, the MORryde CRE3000 Equalizer part #MR87ZR will work for you and will clear the block you have in your hanger. The distance above the top of the bushing on this equalizer is right at 1/2 inch which it looks like you have more than enough…

view full answer...

Answer 5

I attached a diagram showing how a breakaway switch, like part #420000, would be wired to a trailer mounted battery like the one on your Loudo dump trailer. With this type of setup you would not want to pull the breakaway switch with the trailer…

view full answer...

Answer 6

Typically, the 5th circuit of a 5-way is for a reverse light circuit. I have a solution for you, but you will not be able to use the Adapter 7 Pole to 5 Pole Flat #A75TB to activate your trailer brakes as it has an empty port where the brake output…

view full answer...

Answer 7

Hey Joe, thanks for reaching out about the Demco Stay-IN-Play Duo #SM99251 installation on your 2021 Jeep Gladiator! We recommend also installing the Roadmaster Stop Light Switch Kit #RM-751497 so that you get an accurate readout on when your brake…

view full answer...

Answer 8

You'd just have to physically go out to your trailer and measure the angle. So to do this, you'd need to get a protractor or something similar and place it on the edge of the inside on one side of the trailer frame, and check to see if the…

view full answer...

Answer 9

Hey Rylan, I checked with Demco for you, and the Demco A-Frame Cast Head Coupler #DM37ZR will need Grade 5 hex bolts for installation. We don't have these but they can be found at any local hardware store.

view full answer...

Answer 10

I would use a protractor, see photo, place the protractor on the edge of the inside of one side of the trailer frame and the other inside edge of the trailer frame should be parallel with the 50 degree line on the protractor. Another way to verify…

view full answer...

Answer 11

Hey David. Based off of wheel base the MORryde AllTrek 4000 Equalizers for Tandem Axle Trailers item #MR29DR is going to be the closest option. However, I recommend measuring one of your current equalizers so we can be sure this is the best fit. A…

view full answer...

Answer 12

Hey JT! Sorry to hear about your trouble with the leaf springs. Hopefully there wasn't a lot of damage and everyone stayed safe. From what I have found the 26E-3500 is the same as the Dexter 072-027-00. This is the 6-Leaf Double-Eye Spring for…

view full answer...

Diagram Showing How Trailer Brakes are Wired

Featured Help Information

Miscellaneous Media

Continue Researching