The “RV Standard” For Trailer Wire Colors

Starting at the main wiring connector, trailer wire colors help us trace the conductors to all the proper electrical connections.  The colors are specified by the various standards such as the SAE ( Traditional ) standards, or the newer RV Standard for trailer wiring.

So, what is the big deal about trailer wire colors?  A wire is a wire, right?  Yes, almost.  Certainly, the most important thing is the functions of what the wires do, like illuminating the correct lights.  That happens by following the pin standards so the trailer connector we plug into our car matches the functions wired into the trailer.

Colors for the wire insulation are the way we trace the connections.  This is how we know it will work with the tow vehicle it connects with.

Standards For Trailer Wire Colors

While there are many standards, they all have a purpose.  Interestingly, there are 2 standards that most cars and trucks are wired with from the factory.  And, these are the same 2 standards that most trailers come with.  Matching these is the best way to make sure your trailer will work with most tow vehicles.

Why are there 2 standards?

That is a really good question for which we don’t have a good answer.

Trailer Wire Colors 4-Pin ConnectorThe SAE J2863 is the overwhelming standard for trailer wire colors with a 4-Pin flat connector.  (The 5-Pin flat connector is similar, and still following the SAE standard.)  Read more in the Trailer Wiring Diagram article.

The SAE J2863 also applies to the 7-Pin Blade connector by adding some wires.

In contrast, the RV Standard is different, and only applies to the 7-Pin Blade connector.

In this article we will discuss the 7-Pin Blade connector – which is by far the most common – and it is the one with the 2 diviating standards.

(Note:  There are other standards for other connectors, especially in the industrial realms.  Some have round pins, some have blades.  If that is what you have, see this post by Curt Manufacturing for help with wiring.)

Trailer wire colors for both the “SAE Standard” to the “RV Standard” are in the chart below to compare.

RV Standard vs. Traditional / SAE Trailer Wiring

For the 7-Pin BLADE connector, only the 7-Pin, there are 2 main standards – SAE J2863  (“Society of Automotive Engineers” also called Traditional), and one they call the “RV” Wiring Standard ( RVIA/NFPA ).  The connections are the same, but the colors are different.

That means a trailer wired with the colors of SAE will connect just fine with a tow vehicle wired with the colors of the RV standard – and vice versa.

Personally, I think the RV standard just adds confusion for no reason. The SAE Standard keeps the same colors for the main functions – consistent with the 4-pin & 5-pin flat connectors – which makes sense.  Unfortunately, the RV Standard scrambles the colors for no apparent reason (like flipping green and brown).  Stupid to add confusion IMHO, but whatever.  They both exist, so we have to deal with it.

Hey, Electricity is color blind, so in the end, it is the connection that matters.  Both standards connect the same, and use the same pins for the same functions.  So is there a point to having 2 color standards?

Pins Of The 7-Pin Blade Connector

In reality, the actual connector pins are NOT numbered, but we show them with numbers here so it corresponds with the chart of trailer wire colors below, AND with the numbering we show in the Trailer Wiring Diagram article.

Here is the 7-Pin Trailer Wiring Connector with pin FUNCTIONS:

Trailer Wire Connections RV Standard
 

Trailer Wire Colors By Function

In the table below, we break out trailer wire colors by function, and by the pin numbers above.  (See the Trailer Wiring Diagram page for the 4-pin and 5-pin connector information.)
 

Trailer Wire Functions By Connector & Color Code
Traditional / SAE Colors – And – Colors for the RV Standard
Connector Style Pin Function SAE
Color
Description RV
Standard
7
Pin
5
Pin
4
Pin
1 Ground White Ground Wire for all
trailer electrical functions
R
V
 
i
s
 
7
 
P
i
n
 
O
n
l
y
White
2 Tail Lamps
Running Lights
Side Markers
Brown All normally ON lights.
Tail, Running & Side Markers
Green
3 Left Brake Light
Left Turn Signal
Yellow Multi-function signal for the
Left Side Rear Tail Lamp
Red
4 Right Brake Light
Right Turn Signal
Green Multi-function signal for the
Right Side Rear Tail Lamp
Brown
5 Brake Blue Electric Brakes Control
or (5-Pin only) Surge Brakes
Blue
6 Aux Power Red*
(or Black)
Vehicle Power +12V
Battery charging / Accessories
Black
7 Reverse Lights Purple*
(or Gray)
Back Up Lights
/ Surge Brake Control
Yellow
* Note:  Some vendors deviate by changing Red to Black, or Purple to Gray.  Color deviations do not change the pins, or the function.
See SAE Colors By Function In The Trailer Wiring Diagram Article

 
Colors are great to easily see what wire goes where.  Consistency is also good – which is why we like the Traditional SAE standard better.  The first 4 functions have the same colors on 4-Pin, 5-Pin and 7-Pin connectors.  That makes more sense to me because it is consistent.

In our trailer wiring diagrams we show colors for the SAE ( J2863 ) aka “Traditional” Standard.  If you have the RV Standard ( RVIA/NFPA ), the connections are the same, but as in the chart above, some colors are different.  Since the connections are the same, just color our diagram wires different and you will have the RV standard in a trailer wiring diagram.

Which Standard Should I Choose For My New Trailer Build?

Trailer Wire Connectors - 7-Pin RV StyleIf you need more than the simple 4 functions, we definitely suggest using the 7-Pin Blade connector.  It is the most common, and it works with both the SAE and the RV standards.  (Just leave the unused terminals blank – if you only have 5 or 6 functions.)

What about the RV standard?  All I can say is it exists, and this is the way many trucks and trailers are wired.  While the 2 standards only differ by the wire colors, the pin positions and functions are the same.  That means both standards will work with the same tow vehicle.

Which standard should I choose?  I suppose it does not matter, because they both connect the same, so choose your favorite, and wire your trailer that way.  Personally, I prefer the SAE standard because it is consistent with the 4-pin and 5-pin connectors.  That makes it easy to work with for all sorts of trailers, AND, the bundles of colored wires (the 4 main functions) are easy to get.  However, the choice is up to you.

The 7-pin wire bundles are available in both standards.  For example, you can find both on Amazon, readily available.

Trailer Wire Color Variations

All the standards have colors assigned to functions, but that can be confusing because the colors are not always consistent.  For instance, with the SAE standard we might see a Black wire instead of Red, or a Gray wire instead of Purple.  That is not the best, but don’t let the color discrepancies confuse you.

We often see similar color discrepancies with other standards too.

If your colors don’t match, then GO BY THE FUNCTION, NOT BY THE COLOR.  That goes for all the standards.

Wiring Your New Trailer – RV Standard & SAE

One of the tasks involved in building a new trailer is wiring.  We have to set all the lights, run all the wires, and make all the connections.  Some good tips for wiring are in this article about Trailer Lights and Wires.  Even more tips are in the article about Breakaway Kits.

Trailer Colors Junction BoxWe will add one more good tip here for handling the wiring complexities with trailer wire colors.  If you can, then use a junction box.

With a good junction box, you can wire the trailer with the SAE standard, then buy and wire in the tow vehicle connector with either the SAE or the RV standard.  Make the connections in the junction box according to function, and you are good to go.  Just use the chart above to match the wire functions.

Finally, mark or tag all the functions in your junction box.  The marking acts as documentation so if you ever have a problem down the road, you have all your notes about which wire does what.  That will definitely make it easier to work with later.

Good Luck with your Trailer Wire Colors!

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