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


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


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:
Michael H

Tim H.


Hello, If I use a 7way cable connector to my towed car. Can I use the 7way to connect to my car and charge my car battery?

Etrailer Expert

Jenny N.


@TimH Yes you can use the 7 way [or 6 way] to maintain the vehicle's battery charge as long as the motorhome has a charge line run to the battery. You would want to check the 7 way to make sure that the 12V hot lead is active by using a circuit tester like part # PTW2979. If not you can use part # RM-156-75 to run a charge line from the RV battery to the RV 6 or 7 way. You would also need to make sure you have a 6 or 7 way on the front of the towed vehicle. And use part # RM-156-25 to connect to the vehicle's battery.



Totally new to this, so go easy ;) Doing a ground-up rebuild of a 4'x8' single axle utility trailer that will have a basic lighting setup, but I would also like to install a powered winch (i.e. Badlands 2500 from Harbor Freight). I would like to wire the winch into the lighting harness (or get a harness that includes the necessary wiring) so that when the trailer is plugged in to my truck (has 4-pin and 7-pin connections) everything will work. What's the best way to go about this? Is there a 7-pin harness I can install and just hook up all the lights and the winch to? That would be ideal. If not, I have a 4 pin harness already; how can I tie the winch in to that?

Les D.


@Moriarty I would install the etrailer # e99011 7-way cord and junction box. This will give you a secure place to make all of your connections, and give you a standard 7-way connector that many vehicles can connect to . If you use a 5-way or 6-way connector to run from truck to trailer you will not find many trucks that could connect to that.

Jim K.


My 2019 Minnie Winne has a 7 pin connector in rear for flat towing. What wiring harness/connector do I need for my 2018 Wrangler Unlimited? I want to get the patriot II, can I keep it plugged in recharging while driving, through the RV connections or do I need to install a 12v hot wire for the Patriot II?

Etrailer Expert

Jon G.


Here are some shopper's guides we put together for Jeep owner's that breaks down everything that you need whether you have the JK or the JL.



any plug and play harnesses )round 7)for a 2015 Chrysler Town & Country dad mobile, have a pop up for it

Etrailer Expert

Chris R.


For your Town & Country you can use the Tekonsha T-One # 22121, which includes everything needed to install a fully functional 7-way connector.

Darin F.


I just bought a 2019 Ford Ranger Lariate w/ tow package in March. Ive towed my camper twice; it seems the trickle charger from the 7 pin is not working (so the mini fridge in the camper wont run to keep things cool while traveling.) If the tow package missing this feature, or is there something I have to turn on?

Etrailer Expert

Chris R.


The 2019 Ford Ranger should have that 12V circuit activated as part of the tow package, but it's a little odd in how you actually get it to send power. I linked a separate answer page below that does a nice job of explaining this.



@DarinF — Unless you have a residential fridge with an inverter your tow vehicle will have virtually no affect on whether your fridge will run. Your fridge can run in one of two conditions: 12V AND propane, OR shore power. If you have only 12V power available (such as when towing), your fridge needs propane to stay cold; the 12V runs the circuitry, burning propane cools the unit, and the TV charge on the battery should be able to keep up with that demand. The cooling process of the fridge does not run directly on 12V. Even if your battery is not being charged by your tow vehicle, assuming a healthy battery, your fridge should run on propane for long enough for a day on the road with just the charge on the battery. But there are A LOT of factors that work into that. The decision whether to run the fridge on propane while traveling has been widely covered here and elsewhere, so that decision is up to you. Personally, I run mine on propane in transit and always have. My fridge runs "end to end", meaning I keep it plugged into shore power at the house, run it on propane (or generator) in transit, and shore power/generator while camping. Same for the ride home. I don't turn it off until I have all the food out at the conclusion of a journey. If you don’t want to run the propane while in transit your food should still stay cold. Just make sure your fridge has had long enough to become cold and the food you added is cold as well. If you still can’t travel at least 8 hours without your food getting warm then you have something wrong with the fridge like maybe the seal leaking. Also keep in mind that some very new campers are made to automatically switch off the LP when the camper senses motion.

Steve R.


@DarinF the fridge isn't meant to run off the battery. I use shore power the day before a trip to cool the fridge, then plug it back up when at the camp site. They run on 110 ac and your battery is 12 v dc

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