equipment trailer wiring.

[mx842]

Does anyone here have any experience wiring older trailers to these newer trucks. The trailer has electric brakes. It has a round 7 point pin connector on the trailer and my truck has the spade type connector. I bought an adaptor but when I hook that up the brakes lock up when I try to move. I figured that out, it was the break away box and I went and got one of those and a new battery. Now the trailer will move but I have no lights at all on the trailer. All the wiring on the trailer and wrapped with a plastic binder and they painted over that, and I can't see what any of the colors are going to the front. It's gotta be something stewpid I just can't get my head wrapped around it.

 

[Rosher18]

If the spade is a 4-pin spade connector then your truck isn't wired to control trailer brakes.

 

[TractorTech]

You can remove the connector on the truck, wire in a 7 pin connector and add a brake controller.
Without a brake controller, you will not have any trailer brakes.

https://www.etrailer.com/vehicle-finder.aspx?hhcat=bc&furl=-pt-Electric&gclid=EAIaIQobChMI34X4ytu6gQMV7wWtBh1l0Q4fEAAYASAAEgLvLPD_BwE

 

[LD1]

Pics would do wonders.

I have wired and rewired dozens of trailers. What is the "spade" type connector you refer to? Are you talking like the 4-wire flat connector previously mentioned?

Or are you saying the truck has a 7-way....but the actual contact pins are spade type. And the 7-way on the trailer has round pins?

IF you have the standard 7-way on the truck....and the trailer plug has "round" pins....thats more of an RV thing.

If it was mine....Id get a 7-way plug....forget adapters, just another possible bad connection when towing. Put a new plug on the trailer.

When you get the old plug off the trailer, I would assume you can see some wire colors that werent painted within the connector itself. Step 1 is figure out which one is ground. (current color coding for trailers is white).

Then tank a battery and hook that white to ground. One at a time give the rest of the wires 12v and see what lights up or activates.
Current equipment trailers are
Red = 12v auxilary (keeps breakaway battery charged)
Yellow = Left turn/brake light
Green = Right turn/brake light
Brown = taillights
Blue (sometimes black) = Electric brakes

Equipment trailers almost never use the 7th pin (the center one) as thats for backup lights.

So figure out what is what on the trailer side, make a note. Then just wire up a new connector to plug right into your truck. A new 7-way to put on the trailer is probably gonna be cheaper than the adapter you bought

 

[nisaacs]

I agree^^^

Get a 7 way molded plug cord and junction box and start from scratch.

https://www.etrailer.com/faq-wiring-7-way.aspx

 

[LD1]

I agree^^^

Get a 7 way molded plug cord and junction box and start from scratch.

https://www.etrailer.com/faq-wiring-7-way.aspx

View attachment 822462View attachment 822463

Thats the kit I used on my most recent trailer which was a total re-wire.

The wire color of the molded plug I got used RV-standard wire colors so my above reference is inaccurate if thats the route to go.

For for simplicity....I'd just get one of the two piece plastic replacement ends and wire on in place of the round-pin style on the trailer currently. That is assuming the rest of the wiring is okay on the trailer.

Either way....step 1 IMO is cut off the existing trailer plug (or unhook it if it comes apart) and identify what wires do what, and make sure there is no other issues with trailer wiring.

 

[Fixastuff]

There's also a round metal "industrial" plug with different wiring.

 

[LouNY]

There are two different wiring standards for the 7 way flat connector and then more for the 7 pin round connector;

And we still haven't shown the various 7 pin round such as the Europeans.

 

[nisaacs]

There are two different wiring standards for the 7 way flat connector and then more for the 7 pin round connector;
View attachment 822465
And we still haven't shown the various 7 pin round such as the Europeans.

Most vehicle factory plugs are the RV Standard and most trailer wiring is now the same. I have 4 factory trailers and they all work in my trucks. When I do a rewire I follow the 7 way RV style. I just did two horse trailers from scratch. I also run trailer brake wire down each side. Most oem trailer brake wire is down one side then they cross over and wire the other side. The standard two way wire for brakes has gotten so expensive I save my damaged drop cords and use that wire. I try to stay with 14 gauge which is enough when you run two sets. Thats why I like the junction boxes, a lot of access.

 

[LouNY]

Most vehicle factory plugs are the RV Standard and most trailer wiring is now the same. I have 4 factory trailers and they all work in my trucks. When I do a rewire I follow the 7 way RV style. I just did two horse trailers from scratch. I also run trailer brake wire down each side. Most oem trailer brake wire is down one side then they cross over and wire the other side. The standard two way wire for brakes has gotten so expensive I save my damaged drop cords and use that wire. I try to stay with 14 gauge which is enough when you run two sets. Thats why I like the junction boxes, a lot of access.

View attachment 822467
View attachment 822468

Yes, light duty trucks (pickups) follow the newer RV standard, after that you never know.

 

[mx842]

If the spade is a 4-pin spade connector then your truck isn't wired to control trailer brakes.

I wasn't worried about the brakes as much as I was the lights. I have a 2019 Ford F250 that has a brake controller built into the dash so it has a 7 pin spade type plugin. The problem is this trailer has a 7 pin round pin type plug so I had to buy that adaptor that dangles behind the truck. I was trying to figure out how to just put a 7 pin female plug on the trailer and not have to worry about that heavy adaptor. No matter how I wired it, it won't work without that adaptor.

 

[mx842]

Most vehicle factory plugs are the RV Standard and most trailer wiring is now the same. I have 4 factory trailers and they all work in my trucks. When I do a rewire I follow the 7 way RV style. I just did two horse trailers from scratch. I also run trailer brake wire down each side. Most oem trailer brake wire is down one side then they cross over and wire the other side. The standard two way wire for brakes has gotten so expensive I save my damaged drop cords and use that wire. I try to stay with 14 gauge which is enough when you run two sets. Thats why I like the junction boxes, a lot of access.

View attachment 822467
View attachment 822468

That's what has been the problem the plug on the trailer is the heavy-duty commercial type plug, 7 pin round on it. My truck has the 7 blade spade type connector

There's also a round metal "industrial" plug with different wiring.

That is what's on the trailer. 7 pin round pin plug.

 

[Rustyiron]

I also would start with the assumption that the trailer wiring has "played with" and probably needs attention front to back.

 

[mx842]

You can remove the connector on the truck, wire in a 7 pin connector and add a brake controller.
Without a brake controller, you will not have any trailer brakes.

https://www.etrailer.com/vehicle-finder.aspx?hhcat=bc&furl=-pt-Electric&gclid=EAIaIQobChMI34X4ytu6gQMV7wWtBh1l0Q4fEAAYASAAEgLvLPD_BwE

My truck already has a factory brake controller and I really don't want to change the plug type on the truck I have 4 trailers that I use and all of them use the 7 pin spade plug-in type accept this one.

 

[LouNY]

Check out the Q and A on this page, your 7 pin round is likely wired the older Heavy Duty way.
https://www.etrailer.com/Trailer-Wi...aUaAv_HEALw_wcB#exp-productdetails=.questions

 

[mx842]

And to, LD1.......I only bought that adaptor so I would have lights for the 60-mile trip home but I never got out of the parking lot with it hooked up because of the brake issue.

 

[TractorTech]

My truck already has a factory brake controller and I really don't want to change the plug type on the truck I have 4 trailers that I use and all of them use the 7 pin spade plug-in type accept this one.

A lot of back and forth on this. It would have been best to explain that your truck is tow ready and the wiring on the old trailer not clear. LouNY has what you need here.

 

[mx842]

A lot of back and forth on this. It would have been best to explain that your truck is tow ready and the wiring on the old trailer not clear. LouNY has what you need here.

Check out the Q and A on this page, your 7 pin round is likely wired the older Heavy Duty way.
https://www.etrailer.com/Trailer-Wi...aUaAv_HEALw_wcB#exp-productdetails=.questions

I think I mentioned that in my second post at the top of this page. I have been to e-trailer and read those answers. As someone else said why not just put a new Rv style plug in on the trailer? I tried that and I never got it to work. None of those drawings show that jumper that jumps the black wire to the brown and if I wire it that way it will work with the adaptor but not when I wire it straight. I'm thinking now I'll just leave that adaptor in the line; it works that way so to heck with it. I'll just wire tie the thing up so it's not hanging down so much and be done with it. Thanks

 

[LD1]

I think I mentioned that in my second post at the top of this page. I have been to e-trailer and read those answers. As someone else said why not just put a new Rv style plug in on the trailer? I tried that and I never got it to work. None of those drawings show that jumper that jumps the black wire to the brown and if I wire it that way it will work with the adaptor but not when I wire it straight. I'm thinking now I'll just leave that adaptor in the line; it works that way so to heck with it. I'll just wire tie the thing up so it's not hanging down so much and be done with it. Thanks

Take the round heavy duty connector off. Establish your ground.

One by one give each wire 12v and see what happens. Make note.
Wire up new 7-way

You say "no matter how I wire it, it won't work"

That's because up to this point you haven't got the correct way yet

 

[LD1]

Most vehicle factory plugs are the RV Standard and most trailer wiring is now the same. I have 4 factory trailers and they all work in my trucks. When I do a rewire I follow the 7 way RV style. I just did two horse trailers from scratch. I also run trailer brake wire down each side. Most oem trailer brake wire is down one side then they cross over and wire the other side. The standard two way wire for brakes has gotten so expensive I save my damaged drop cords and use that wire. I try to stay with 14 gauge which is enough when you run two sets. Thats why I like the junction boxes, a lot of access.

View attachment 822467
View attachment 822468

Just for clarification.....

Equipment standard vs RV standard are no different in plug or layout.

It is ONLY the wire color.

The truck is always gonna have the taillights at 11 o'clock and ground at 7 o'clock on the 7-way. (Most frequent ones I check)

But an equipment trailer is gonna use a brown wire for tail lights, and an RV is gonna use the green wire.

As for trucks.....I don't think they follow a standard and use their own wire colors that make no sense