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.