How to Identify Functions for Each Wire on a Trailer

Question

Question:

How do I connect the wires? When I got the trailer the black wire was not connected to anything. Hock up a 4 wire green , yellow,brown , white. To a 6 wire black white green yellow brown red

asked by: Camilla

0

Expert Reply:

Trailer wiring often uses specific color wires for a particular lighting function but there is no guarantee that your trailer uses the common wire colors. This just means that you'll test the wires on the trailer to see what each one does; then you will know how to connect it.

You can refer to the linked article on trailer wiring that shows the usual configurations of 4-pole, 5-pole, 6-pole and 7-way wiring. Photos are included to show you the usual wiring colors for each function.

In a 4-pole setup the wire colors/functions are typically:
Brown wire is running lights
Yellow wire is LEFT turn and stop light
Green wire is RIGHT turn and stop light
White wire is ground

For all wires on the trailer you can simply apply 12V power from a car battery to see what function each wire activates. Ground the battery negative terminal to the trailer frame and then one by one apply +12V power to each wire to see what each wire connects to. The 5th and 6th wires on the trailer are likely to be for a 12V power feed to help maintain a trailer-mounted battery and a brake signal circuit to activate electric trailer brakes.

expert reply by: Adam R

0

Answer 1

Since yellow, green, and black are not standard trailer taillight wires, we will need to do a little more digging to find the functions of the different wire colors. To determine the function of the trailer taillight wires, you will want to trace the…

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Answer 2

When it comes to a 4-way flat connector to a 7 round plug adapter I recommend The Hopkins Endurance, Flex-Coil Trailer Connector Adapter - 7-Way to 5-Way or 4-Way Flat with Nite-Glow #HM47075. This heavy-duty coiled cable has a weatherproof…

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Answer 3

The Hopkins Heavy-Duty, Coiled Trailer Connector Adapter, #HM47075, measures 3 feet long when stretched. This will most likely not be long enough for most flat towing applications unless the 4-Way end on the vehicle has some slack that you can pull…

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Answer 4

There is a 6-wire Flexo-Coil cord, #RM-1046-R, with just the wires but there is no 7-wire option. There is also a 4-wire version, #RM-1064-B. The #HM47075 cable is only going to have 5 wires inside since the one end can only be used on a 5-Way or…

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Answer 5

Hello Donald, thanks for reaching out. Since the wires on your trailer are not color coded to the typical standard, the best way for you to determine the correct function for each wire will be to use a wire tester such as part #PTW2991. You can probe…

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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

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 8

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 9

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 10

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 11

The #84 spindle is just a common way to identify the spindle dimensions typically used for 3,500 lb axles. So instead of listing out the parts, people can just say they have #84 spindles and it's easier to know what fits it. The CE Smith Trailer…

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Answer 12

The 5.30-12 tires, being wider, are going to make more contact with the road. This means that the noise, and heat build up will be higher than a 4.80-12 tire but the rolling resistance will actually be less because the tire is larger diameter. The…

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How to Identify Functions for Each Wire on a Trailer

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