What Are The Standard Colors And Functions For A 4 Flat On A Cargo Trailer

Question

Question:

Ive got 5 wires black white brown green and yellow. Can I use a 4 way flat plug and what wire configuration do I use. On the replacement I bought it only has 4 wires. White brown yellow and green

asked by: Lance G

0

Expert Reply:

The standard 4 Flat will have the White (ground), Brown (running lights), Yellow (left turn and brake), and Green (right turn and brake). Black will typically be used for 12 volt power, but can also be any number of things. The only way to know for sure what it is used for will be to trace it to its source. However, if you only need the 4 standard functions, you can definitely just cap that off and use something like the Hopkins 4 Flat # HM38168.

With that said, if you do trace it and find that it goes to reverse lights, you can use the 5 Flat plug # 20017 to get the extra wire attached. The Tow Ready Vehicle Side 5 Flat # 20036 can then upgrade the 4 Flat on your vehicle with the wire being spliced into a wire going to your reverse lights. Then your trailer will have reverse lights when you back up with it.

If it ends up being a 12 volt power line to something, it will be much the same, but I recommend putting a 7 Way plug on instead of a 5 Flat. A 7 Way, like the hopkins # H20046, can also be used if it is a reverse light wire and if you already have a 7 Way on your vehicle, I recommend going this way. The only difference between wiring this for a 12 volt line will be which wire you connect the black one to. I have the functions listed below if you choose to go this way.

Brown - right turn/stop,
Red - left turn/stop
Green - running lights
Yellow - auxiliary/reverse light
White - ground
Black - 12 volt hot lead

expert reply by: Lazer S

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Answer 1

From the image you attached, I think what you have is each of the taillight circuits on your 4-way have two wires ran to them for each side of the trailers wiring. You can wire the two wires of each pin to the single wires of a new 4-way allowing the…

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Answer 2

Connecting the brown running light wire in standard 4-pole wiring to both tail lights will require a jumper wire from one side of the trailer to the other, or you can install what's called a wishbone harness that has dual brown running light…

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Answer 3

I recommend moving away from the Adapter 4-Pole to 5-Pole Trailer Wiring Adapter #47515 and going with a Buyers Products Trailer Connector Adapter #337TC1474P. The wiring and connectors used on the 4-way harness are not designed to be used with the…

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Answer 4

If you don't have brake or turn signals on the right side of your trailers then the most likely cause of this issue is just a blown fuse, F81 in the engine bay fuse box which is a yellow 20 amp. If the fuse is good then check the wiring behind…

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Answer 5

What you have is a 4-way wishbone harness like part #A35W42B. It's a 4-way with two brown wires so you can run a running light circuit down each side of the trailer and not have to use a jumper wire to go from one side to the other. It makes…

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Answer 6

Did you have a 4-pin connector that had 5 wires or was it a 5-pin connector? There is a big difference since you normally see a 5-pin connector on a boat trailer with the 5th pin used for an electric reverse lockout solenoid on a brake actuating…

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Answer 7

I went out to the warehouse and pulled a 35 ft. Wishbone 4-Way Trailer Wiring Harness, #A35W42B, and used a wire gauge tool to measure the wires. The copper wire itself is 20 gauge. If you measure the wire with the insulation on it then it is thicker…

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Answer 8

You have it right so far, the 4-way connector is just as you have stated. Remember that Yellow has a L in it so that is the left side brake/turn signal and green has a R in it so that is the right side brake/turn signal. The colors for wiring a 7-way…

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Answer 9

The Equal-i-zer Shank part #EQ90-02-4900 would be your best option to give you the amount of drop you need to tow your trailer level. The Curt shank you have now part #C17131 can do up to 2 inches of drop but the Equal-i-zer can do up to 6 inches so…

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Answer 10

It sounds like you have a classic ground issue on your trailer that is preventing proper voltage from reaching back to the tail lights. What I recommend doing is first making sure the main ground for the trailer connector is secured to a clean bare…

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Answer 11

The red wire is the turn signal wire and will be run to the green wire of your harness if its the right turn signal side, and the black wire will run to the brown wire of your harness. The yellow wire from your harness will run to the left turn…

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Answer 12

If you still have the plunger end that goes in the break away switch, then you can simply insert the plunger back into the switch and that should cut off the power to the brakes on your trailer. If you no longer have the plunger, then you can either…

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