Replacing 5-Way Connector with 8 Wires on Boat Trailer

Question

Question:

The wiring harness on our boat trailer is bad. There are NO replacement plug that looks like ours. It has 5 pins and eight wires coming out of bottom. One blue, one green, one yellow, two brown and three white. One of the white ones has a brown line on it. Anyway total of eight wires. Looking for a wishbone harness still only has 6 at most. How can I find one with eight? I have searched and read all forums to help us with this. But have found no answers. I have included a photo. Please help. I wanna go fishing!!

asked by: Jana J

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Expert Reply:

We definitely have what you need to replace the 5-Way connector on your boat trailer, but there's not going to be a pre-made 5-Way harness that includes 8 wires. As you mentioned the most you will likely find is a wishbone harness like # A25W5B that uses 6 wires (a separate running lights circuit wire for each side of the trailer). A previous owner or the factory simply used a non-standard wiring setup when installing the connector and wiring on your trailer.

With all of that being said, it's still going to be easy enough to swap out the connector. Your best option will be to simply cut off the existing 5-Way and replace it with a new one like the above-mentioned harness. Since a 5-Way doesn't usually have 8 wires, you will just need to test each of them for function with a circuit tester like # PTW2979 when connected to the tow vehicle or by simply applying 12V power directly to each wire if you aren't connected.

Once you know the function for each wire you will be able to splice into the new connector. On the 5-Way # A25W5B the white wire is ground, the brown wire with green stripe is right side running lights, the brown wire with yellow stripe is left side running lights, the yellow wire is left side stop/turn, the green wire is right side stop/turn, and the blue wire is auxiliary/reverse.

If I had to guess you most likely have a few ground wires on your current setup (but I still recommend testing to be sure) so you will probably just have to splice in multiple wires from the trailer to the ground wire terminal on the new 5-Way. I recommend using heat shrink butt connectors like # DW05744-10 to provide a good seal to avoid any shorts from exposure to the elements (especially since it's on a boat trailer).

If you have any other questions along the way please feel free to reach out! We want to get you fishing again as quickly as possible.

expert reply by: Chris R

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Answer 1

A standard 5-way like the part #HM47910 would work great to replace what you have. You'd just run all of the white wires that you have (all three) to the single white wire of this connector, both the brown wires to the single brown of the…

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Answer 2

When wiring a 7-Way on your trailer with 5 wires, your green wire will be right turn/brake, the yellow wire will be left turn/brake, the brown wire will be the taillights, and the white wire will be the ground. You will want to find out if the blue…

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Answer 3

For starters, a quick-fix type connector shown in your photo is typically a good choice for an emergency repair, but I wouldn't use it as a permanent fix. It looks like your trailer wiring has 3 separate grounds and 3 separate running lamp…

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Answer 4

What you have is a 5-way with a double wishbone, which means it is likely a double wire for marker lights as well as a double ground. You can replace your 5-way with another wishbone-style but it does not need to be a double wishbone with 7 wires,…

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Answer 5

There is not going to be a 5 flat that has 8 wires; the functions of the 8 wires are likely ground, running light circuit (split into 2 wires at the plug), left turn, right turn, brake lights (possibly split at the plug), and output to reverse…

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Answer 6

It sounds like you are speaking of the wires for the brake magnets. If this is correct, you will need to connect one of the wires to the brake controller output wire on your trailer connector and the other wire will need to be grounded to a clean…

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Answer 7

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 8

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Answer 9

The only difference between 7-Way Utility and 7-Way RV is the color of the wires. The pin outs are the exact same so either would work just fine with the other. If you check out the picture I attached you'll see that the functions are all the…

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Answer 10

When wiring a trailer connector, it is best to wire by function, as wire colors can vary. We have an excellent wiring diagram on our website, I will provide you a link so you can look at it. If you are looking at the inside of the trailer connector…

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Answer 11

That's a very good question, we tend to be extra cautious and say to use 10 gauge wire because that would be more than enough. When you get into longer trailers that will end up using a lot of wire the heavier gauge wire becomes more necessary.…

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Answer 12

First you will need to remove the old hydraulic equipment. Remove the surge coupler or actuator, remove all the lines, and finally remove the brake assemblies. If you have 10 inch diameter hub and drums, you may need to replace those as well. If you…

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Replacing 5-Way Connector with 8 Wires on Boat Trailer

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