Wiring for a 7 way plug has 8 wires??

[johnw91]

Hey Guys, just got a new boat and the plug wont reach my truck. I bought an extension online and it doesnt seem to work, so I am thinking about just rewiring with a longer extension. Well I bought a 7 way extension the other day, and it has 7 wires coming from it. My boat trailer plug though has 8 wires going to it?? Attached is the picture below. Any idea how I could make this work? The one I bought seems pretty standard and the wires match up to most universal 7 way wiring diagrams, however I can't find anything at all about the wiring for my Nitro trailer. It is a 2010 dual axle trailstar trailer. Any advice at all is greatly appreciated. Thanks.

Trailer wiring.jpg

[Danrude]

The two brown wires for the running lights are tied together at or in the plug on the trailer.

[cconn]

I would get a wire test light and verify. I see 3 white wires, which should all be neutral (grounds) and probably tied together at plug.

[billnorman1]

One thing I've found, the vehicle wiring color code doesn't necessarily match the extension color codes, don't go by that.

[CatFan]

Some wires are just duplicates for each side of the trailer. You only need 7 wires to the truck for everything to work.

[fishnfireman]

If the trailer is wired correctley and it's not a foreign made truck you will only need 5 of the seven connections. Most of the connecters are labeled. Just be aware that some will have the center pin wired different.
From what I see in your picture …
1. The two brown wires can be Y'd together for the clearance lights.
2. the yellow wire is left turn signal and brake.
3. green is right turn signal and brake.
4. blue is for the brake back up solenoid.
5. the 3 white wires can be Y'd together for your ground.

[gambler1]

What if there is backup lights on the trailer?

[CatFan]

What if there is backup lights on the trailer?

You still only need 5 wires.

[cconn]

What if there is backup lights on the trailer?

They should feed off the same blue wire that the brake solenoid uses.

[gambler1]

Thanks, makes sense.

They should feed off the same blue wire that the brake solenoid uses.