What is the Difference Between a 4-Way and 7-Way Trailer Connector

Question:

What is difference between a 4 pin and 7 pin trailer connector?

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Expert Reply:

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 brakes (requires a brake controller in the vehicle), and a reverse light or auxiliary power circuit.

There are other types of connectors as well. I have included a link to our help article that shows and explains the various connector types.

expert reply by:
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Michael H

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Follow up Questions

Joel M.

Have Titan xd 2016 pro 4x has factory 7 way and 4prong wold like to get 7 way on a old car hauling trailer. Backup lights, brakes. Do you have plug ready for trailer, need to re wire and light whole trailer, and brain transplant for myself. Can you help me please? Thanks 77900

Reply from Chris R.

Unfortunately I can't help with the brain transplant (I'm on a waiting list myself) but I can with everything else! To wire your trailer up with a 7-Way connector, I highly recommend using the etrailer 7-Way Upgrade Kit # e99011 . This allows you to make this conversion and keep all your connections clean. For extra wiring you can use 12 gauge # 12-1-1 for the brakes and 12V circuit and 16 gauge # 16-4B-1 for the lights, both of which are sold by the foot. It sounds like you're also wanting to add or replace some light assemblies as well - I've linked our full selection below if that's the case. I also linked a handy wiring article that you might find helpful. 63274

William W.

Is there an adapter available to go from a 7 pin wire connector on a 2014 ford truck F350 to a trailer plug which is a 9 pin? And if not whats different from a 7 way versus a 9 way? Thank You, 77722

Reply from Chris R.

There isn't a clean adapter available that goes from a 7-Way to a 9-pin connector, but we do have still have solution. I've linked an informative answer page below that details the parts you will need. 63273

Danielle D.

So I have a camper with a 7 round and a vehicle with a 4 flat pin. Can I just buy an adapter or will I not be able to use the brakes on the camper, only the lights? 76473

Reply from Chris R.

If you were to just hook up an adapter like the Tow Ready # 30717 (without running those additional wires) you would only be able to activate/power the signal lights on your trailer. If the trailer has electric brakes a better option is the Wiring Kit # ETBC7 , which includes all the additional wiring needed to activate the rest of the circuits. You'll also need to add a brake controller like the Prodigy P2 # 90885 to your tow vehicle (if you haven't already). 62406

Dennis L.

Can I get a plug and play trailer wiring kit that requires no cutting of wires to go with hitch from you for 2001 freightliner MT45 former snap on truck going to be used as off grid rv? 76026

Reply from Chris R.

There isn't a custom plug-and-play harness available for your 2001 Freightliner MT45 (I really wish there was!). You'll need to go with a hardwire kit like the excellent Tekonsha # 119190KIT for the 4-Way connector. If you need a fully functional 7-Way, you'll then use the Wiring Kit # ETBC7 , which includes everything needed to convert the 4-Way to a 7-Way connector. 62129

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