My Vehicle has a 4-Pin Trailer Plug, but Trailer has 7-Pin Trailer Plug

Question

Question:

My brother SVE only has a 4 plug adapter but my trailer is hard wire for a 7 way plug. What adapter do they make to change the 7 way plug over to a 4 wire plug?

asked by: James B

0

Expert Reply:

If you just need a 4-pin to 7-pin trailer wiring adapter, then you can use part # C57672. This will plug into the 4-pin trailer connector on your brother's vehicle and give him the 7-pin socket for the trailer. Keep in mind, this will only give you trailer light functions. If your trailer has a 7-pin connector, then it likely has electric trailer brakes and an onboard battery.

If you want a fully functioning 7-way trailer socket on his vehicle, then the installation will be a bit more involved, but we have a kit that contains pretty much everything you will need in part # ETBC7. This kit still uses the same adapter I mentioned above and it also comes with the additional wire and hardware you will need. I attached an installation video to show you how a kit like this is installed.

The only component of the towing setup that this kit doesn't include is a brake controller which will be required if you need to use the trailer's brakes. If you want something inexpensive that will get the job done, I recommend picking up the Tekonsha # TK63VR and wire harness # 20127.

expert reply by: John H

0

Timothy

3/31/2024

Hey John, If I have a vehicle with a 7 pin connector and trailers with 4 pin connectors, is there a 7 pin and 4 pin combo unit with a mount that allows me to use either the 4 or 7 pin connection (basically converting my 7 pin to both 7 and 4 pin connections at the same spot)? Can't seem to find this anywhere. Thanks.

Reply

John H.

4/12/2024

@Timothy There are, but the amount of work you might have to put into installing one will depend on what you currently have. If you are comfortable splicing wires, the easiest way to make this change, in my opinion, would be to install part # HM40975-11998. You can simply screw the bracket into the underside of your bumper or somewhere back by the hitch and splice the wires from the pigtail into the wires going into your 7-way. This product comes with a wiring diagram to help you understand which wires are for which signals.

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Jos

6/4/2024

Hi John, would that kit #ETBC7 also charge an RV battery while driving? Thanks, Jos.

Reply

John H.

6/6/2024

@Jos Yes it will. It won't revive a dead battery, but it will top off a battery that is in good working order and it will maintain that battery's charge when towing.

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Rafael L.

4/14/2025

Hi John, I’m trying to get all the parts needed for. 2025 Kia Sorento X-pro model. I have the hitch number, C37RV, and I have the wiring part, C99DR. This vehicle unfortunately doesn’t is not pre wired, I looked. It does have led tail lights. I need to add a 7 way because we will be pulling a small single axle camper that has breaks. We have decided to go with the Echo wireless break controller. What would be the correct 7 way adapter? Also, does the 7 way adapter need to be wired to the vehicle’s battery if the 4 way already has a wire running to the battery?

Reply

John H.

4/14/2025

@RafaelL You're on the right track with the Curt Hitch # C37RV and Wiring Harness # C99DR on your 2025 Kia Sorento X-Pro. Since the vehicle isn’t pre-wired and you’ll be towing a camper with electric brakes using the Curt Echo # C51180 wireless brake controller, the correct 7-way adapter is the # ETBC7 kit. This plugs into your existing 4-way and includes a 7-way socket, mounting bracket, and 12V power wire needed for the Echo to function. Even though your 4-way wiring has a power connection, you still need to run the included 12V wire in the # ETBC7 kit directly to the vehicle’s battery to power the 7-way and brake controller because you'll want the battery charge line (12 volt power wire for the 7-way) to be on a separate circuit from the converter box of the 4-pin harness. This setup gives you full trailer lighting and brake control functionality without needing a traditional wired brake controller in the cabin.

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Rafael L.

4/14/2025

@JohnH What would be the difference between the ETBC7 and the ETBC7L?

Reply

John H.

4/14/2025

@RafaelL The only difference is that ETBC7L comes with a single wire for the 12-volt charge line and ETBC7 comes with a dual wire. I'd go with the dual wire because you can run your power and ground all the way up to the battery in one run rather than grounding the 7-way adapter at the frame that can rust and corrode over time.

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See All (6) Replies to Rafael L. ∨

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My Vehicle has a 4-Pin Trailer Plug, but Trailer has 7-Pin Trailer Plug

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