Detailed guide on 4-pin, 7-pin and 13-pin trailer wiring harnesses

2022-06-29
Detailed guide on 4-pin, 7-pin and 13-pin trailer wiring harnesses

Detailed guide on 4-pin, 7-pin and 13-pin trailer wiring harnesses

First of all, I would like to explain to you a usage of trailer harness. As an important branch of the RV, the trailer RV is absolutely mainstream in Europe and the United States and other countries. Many people think that a trailer RV can travel as long as it has a car towing it, but obviously it is not that simple. The trailer's charging, lighting and brakes all need to be connected to the towing vehicle.


 
  1. pin trailer wiring harness:
The trailer wiring harness is divided into two parts, the interface on the tractor is called the female, and the wiring harness interface on the RV or trailer is called the male. The common trailer wiring harness is divided into 4-pin type, 7-pin type and 13-pin type. The 4 pin trailer wiring interface is a motorcycle trailer interface, and the male end of the harness has only four wires: left turn signal, right turn signal, taillight, and ground, while the female end of the harness has five wires for brake, left turn signal, right turn signal, taillight, and ground access.

The 7-pin harness and 13-pin harness are both specially prepared for tractor trailer harnesses, compared to the 13-pin harness, which is simpler to install than the 7-pin, so let's talk about the 13-pin harness connection first.
The 13-pin wiring harness is also known as the European wiring harness interface because it is commonly used in European towing caravans. 13-pin wiring harness contains brake lights, left and right turn signals, driving lights, reversing lights, fog lights, long fire wire, ground wire, etc. It is worth noting that there are brake lights but no brakes in the harness. Most European-style trailer RVs use impact braking, so there is no need to connect the brake lines.

13-pin trailer wiring harness

The 13-pin wiring harness contains interfaces for turn signals, brakes, driving lights, reverse lights, fog lights, long fire wire, ground wire, etc. It is worth noting that there are brake lights but no brakes in the harness. Most European-style trailer RVs use impact braking, so there is no need to connect the brake line. When there is the original 13-pin female connector, it can be used directly. The ones like the Land Rover Discovery 4 that have a pre-determined interface are also easier and will have the original factory option to install.

However, more vehicles do not have these interfaces and will require additional wiring. Generally use from the rear taillight wiring program, this program requires attention is to consider the ability of the original car wire and construction safety. If the original vehicle has a female 7-pin harness, you can also consider using a harness converter to convert the 7-pin to a 13-pin harness.
 

7-pin trailer wiring harness

The 7 pin trailer harness, also known as the U.S. trailer harness, has 7 harnesses for the brake lights, running lights, left and right steering, long fire wire, hitch wire and a spare wire. Pickup truck models like the Raptor F150 and Tundra come with the original 7-pin wiring harness female, but note that the original harnesses of these vehicles do not necessarily match the wiring harness of the RV. Like the Raptor F150 the original brake light and turn signal signals are not differentiated and the brake signal needs to be connected according to the actual situation. The specific connection will be provided by the dealer of the RV, and the harness can be debugged according to the drawing.

Another important point is that American trailer RVs have a different brake mechanism than European trailer RVs, and most of them use electric conduction drum brakes. In the absence of ABS, the brakes will easily lock up at low speeds. This is where another piece of equipment, the brake controller, needs to be added.

The brake controller is simple to install and use, with four positive and negative wires, brake signal input, and brake signal output. For American vehicles without a separate brake signal there are now two solutions.
One, using a decoder to drop the brake signal from the original signal stripped out.
Second, there will be a separate brake signal source at the foot pedal location, from which a separate brake signal is derived. This separate brake signal is then introduced into the brake controller. Note that the brake controller has an internal gyroscope, so it needs to be fixed horizontally inside the car. When using the brake controller, the low speed brake sensitivity should be lowered, and the high speed brake sensitivity can be adjusted higher.

The daily use of RVs is not very high, and most of them are used outdoors, so you should check the lights and brakes of the RV every time you connect the tractor and the RV. Don't panic if there is a problem, most of them are just bad contacts, just pinch them with pliers and you're done. The seemingly simple installation of a trailer wiring harness is not simple in practice. Therefore, it is not recommended to install the trailer wiring harness and brake controller on your own, it is best to find an experienced tuning store to do it. After all, it is better to find an experienced tuning shop to do the job. After all, safety is the first priority.



For vehicles that do not have these interfaces, additional wiring will be required. Generally use from the rear taillight wiring program, this way need to pay attention to consider the original car wire capacity and construction safety. If the original car has a 7-pin wiring harness "female" head can also consider using a harness converter to convert the 7-pin harness to a 13-pin harness.
 

The application range of American style trailer drain wire

Mainly used in all kinds of RVs, trailers, trucks, commercial vehicles, off-road vehicles, etc.. Mainly in large pickup trucks, ATV/UTV, function vehicles, including rescue vehicles.
 

Inspection

The trailer wiring harness is the wiring harness that connects the RV to the towing vehicle. But the trailer harness is not only found on the towing RV, the trailer harness is divided into two parts - the male and the female. Many self-propelled RVs are now equipped with a trailer at the rear for towing small RVs or ATVs. It is easy to be damaged because it is exposed outside the body.
Easy to damage: impact, water, sand, aging, short circuit

 

In Los Angeles California, Trailer row plug line service quality merchants:






OReilly Auto Parts
Location&Hours
4040 Eagle Rock Blvd, Los Angeles, CA 90065
Tuesday~Saturday 07:30-22:00, Sunday 08:00-21:00
Monday07:30-22:00
Tele: +13232548655

Customer Review
Eli AguDes
I have to say that Im thankful that my car decided to brake down in front of OReilly, looking at the silver lining. Justin E. was kind, trustworthy and truly cared to help me. Im forever thankful for his patience, understanding and sense of urgency. I noticed also how other employees helped customers in general and they truly cared for all individual situations and needs. Whoever is in charge of this store, has done an amazing job with hiring quality people. I totally recommend OReilly in Eagle Rock.

Mike Dorsey
Justin was awesome! Lots of info and was more than happy to try and order my special parts! Thank you!






AutoZone Auto Parts
Location&Hours
3MXX+4J Los Angeles California
Tuesday~Saturday 07:30-22:00, Sunday 08:00-21:00, Monday Closed
Tele: +13236649807

Customer Review
Alex Visotsky
great store has everything you need!  I bought wires for the car, everything is fine!  the quality of goods is high, polite staff!  recommend!)

KRISTINE LOUISE
Today I went into Auto Zone confused as to which portable battery charger to buy. Although busy when I entered, They showed me where the batteries were and let me know that those were just displays so I waited in line and was helped, I wanted the best one, Alex was extremely knowledgeable and let me know which batteries they offered, was clear on the different price points and let me know which he thought was the best. He went beyond the call of service, because when first checked the charger was not there. Alex having acute awareness of stock knew that there was one left. So instead of telling me sorry, he went looking for it. I left happy with my purchase only to get home and find that I couldnt find how to charge the charger. I called the store and Alex got on the line with me and went step by step on the included items in the box, then helped me locate where to plug in the wire. I was doing it wrong,. Alex was patient, knowledgeable and gave me exemplary service. Thank you Alex for taking out the time to give me the best customer service. ( I bought the NOCO G70)