Solutions for Towing a Trailer with a 4-way with a Tow Vehicle with a 7-Way Connector

Updated 03/22/2013 | Published 02/23/2013

Products Featured in This Question

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(149)

$61.69

4-Pole Trailer End Connector

(39)

$7.47

Adapter 7 Pole to 4 Pole with Tester and Cover

(601)

$12.48

Question:

I have a small, very light weight trailer maybe 300 lbs. I use for my kayaks. It currently has a 4 pole connector but we recently purchased a new vehicle to tow it which has a 7 pole receiver. As I look at the 7 pole set-up the, the red/black, blue and purple wires are for auxiliary power, brake control and back-up lights. This trailer does not have any of these and frankly has no need for them. Can I convert the the 4 pole to the 7 pole plug by simply making the correct connections for yellow, green, brown and white wires and then capping off and taping the red/black, blue and purple wires to the trailer frame? If not how can I convert the 4 pole plug to a 7 pole plug? Thanks.

asked by: John J

Expert Reply:

I think I have a better solution for you. I would recommend you get an Adapter 7 Pole to 4 Pole # 47345. You would simply just plug this product into the 7-way on your new tow vehicle and you would have a functioning 4-way. This option is nice too because if at some point you do have a trailer with a 7-way connector on it you would still be able to tow it.

If you do really want to cut off the 7-way and install a 4-way you could still do this. You would just need to wire by function. For a 4-way you could get a # 18004. You will want to use a circuit tester like the # 3808 to determine the functions of the wires and then wire them accordingly to the 4-way.

On the 4-way you would wire it:

Yellow - left turn and brake
Green - right turn and brake
Brown - tail
White - ground

expert reply by: Jameson C

John J.

2/27/2013

You have this going the wrong way. I currently have a 4-way plug on the trailer and a 7-way socket on the truck that will be pulling it. The other reason I was inclined to cut off the 4-way plug and put on a 7-way plug is that the 7-way plug is much sturdier than the 4-way plug, the prongs of which I find tend to get beaten up pretty easily. Your thoughts?

Patrick B.

3/22/2013

With a 7-way socket on the truck and a 4-pole on the trailer you have 2 options. 1) The adapter Jameson had mentioned, 47345. 2) Up-convert the 4-pole on the trailer to a 7-way to match the truck. Option 1 is simple and requires no splicing. If cutting and splicing is a task you are comfortable with, then option 2 has merit as it will not add another piece like an adapter that could fail. For option 2, you would cut off the old 4-pole from the trailer wiring. Then use a new 7-way plug like part PK12706 to make the conversion. Make sure to follow the diagram on the product page so it is wired correctly. That is the standard accepted pin-out for a 7-way and if your truck 7-way is OEM, then they will have used the same pin-out at the plant.