bing tracking image
  1. Trailer Wiring
  2. CURT
  3. Wiring Adapters
  4. Multi-Function Adapter
  5. 4 Flat
  6. 7 Round - Blade
Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps

Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps

Item # C57674
lowest price pledge
Our Price: $35.84
You Save: 41%
Trailer Wiring
Orders above $99 qualify for Free Shipping
Shipping Weight: 1.29 lbs
In Stock
zoom in icon
slider vertical icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.

Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.

Error submitting comment. Please try again momentarily.

Product Images

In Use/Installed

Customer Photos

Need help with installation?
Locate installers near me
This multi-function, vehicle-end connector converts any 4-way flat, vehicle-end plug to a combination 7-way outlet and 4-pole flat outlet. Lowest Prices for the best trailer wiring from CURT. Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps part number C57674 can be ordered online at or call 1-800-496-5010 for expert service.
  • All Info
  • Reviews (290)
  • Q & A (0)
  • Videos (9)
  • Photos
  • Why etrailer?

CURT Trailer Wiring - C57674

  • Wiring Adapters
  • Multi-Function Adapter
  • 4 Flat
  • 7 Round - Blade
  • Plug and Lead
  • 4 Flat
  • CURT

This multi-function, vehicle-end connector converts any 4-way flat, vehicle-end plug to a combination 7-way outlet and 4-pole flat outlet.


  • Adapts 4-way flat to both 7-way round and 4-way flat
  • Includes integrated test lamps which display proper connections
    • Shows if the wiring on your trailer isn't working properly - burned out bulbs, poor connection, etc.
  • Includes mounting bracket and hardware
    • Distance between vehicle mounting holes center to center: 2-1/4"

57674 Curt Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps

Installation Details C57674 Installation instructions

California residents: click here

Video of Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Curt 4 Pole to 7 Pole and 4 Pole Adapter Review

Hi there, towing enthusiasts. Today, we're going to be taking a look at Curt's 4-way Adapter to 7-Way and 4-Way with Test Light. As you can see here, our trailer has a 7-way connector but our vehicle used to only have a 4-way connector. With this adapter, we are able to break it out and have a 4-way and a 7-way so we can fit our plug in, because without it it's like trying to fit a round peg in a square hole.When comparing this to other similar adapters, the things that I like about this one over those is that it has both the 7-way and the 4-way. Some are just an adapter at the back that will allow you to plug your 4-way into it, giving you a 7-way, but then you lose the functionality of your 4-way unless you we're to unplug it from your 7-way each time. I love having this breakout for your various accessories that you may use.Another feature that really stands out is the tester that's included in it.

This is a great thing to have on hand, because often whenever you have an issue with your trailer, it always seems to be like when you're out on vacation, and why spend time having to go to a shop to get it fixed when you can have a tester right here and you can immediately tell if the fault is with your vehicle side or your trailer side for a quick easy diagnosis so you can get that problem fixed and get back on the road.If you have an existing 4-way connector on your vehicle, this adapter will attach and it'll plug right into your 4-way connection. It'll break that out into a 4-way that you can still access, so if you have accessories that use a 4-way, you're not losing your 4-way, but you are gaining a 7-way. By plugging your 4-way into the connection at the back of this connector, it'll take all those 4-way connections and put it out here in your 7-way giving, you all your necessary lighting, which includes your left turn signal, right turn signal, tail lamps, and brake lamps.We've now plugged in our trailer's 7-way connector into the connection in the back of our vehicle and here you can see our lights are operating on our trailer through that 7-pole connection. This'll keep us safe and legal when using our trailer is and it allows everybody behind us to know our intentions when driving down the road because they can see all of our lighting signals.Now if you we're intending on using a larger trailer that may have had breaks on it or additional accessories such as a power jack, you may need some additional connections here at your 7-way. There are breakout wires for those remaining connections and you can wire those up as well.Of the three remaining connections, one of them will be for your brake signal, which is the output for a brake controller, so you can then add a brake controller.

Next, it also has a charge line cable, which is your 12-volt, so you can charge a battery on your trailer or operate a tongue jack. Lastly is your reverse light circuit, which you can tap into the vehicle, so whenever you backed up on your vehicle, those reverse lights will also illuminate on your trailer.When not in use, our 7-way campus spring loaded, which will help it shut and there is a rubber gasket on the inside which will keep out any moisture, ensuring a long lasting connection. There's also a dust for our 4-way. This one is manual, it's not spring loaded, but it does function similarly, keeping out moisture to ensure long life on that connector as well.Now that we've gone over some of the features of our connector here, let's go over how you would install it on a vehicle that has an existing 4-way and give you some tips and pointers on how to get it completely set up for a full 7-way connection.A mounting bracket does come included with your 7-way adapter. Hardware also comes included to get it mounted up.

You can attach this to the bottom of your hitch, to the bottom of your bumper, wherever you'd like. We're using a no-drill bracket, and this will allow us to secure our bracket to our hitch without having to drill into it, which is nice because you won't chip the paint or anything and you don't have to worry about corrosion occurring at those drilling points. From there, our bracket that came with our adapter bolts directly to this no-drill bracket. If you need a no-drill bracket and you don't want to drill to get the bracket that comes included with it installed, you can pick up these no-drill brackets here at're going to be using this just to take your lighting from the your existing 4-pole connector so you can use it with the 7-pole. All you have to simply do is plug it into the harness that's coming out of the back.

We plugged our factory 4-pole into the 4-pole off of our new harness and then take the white wire coming out of our harness and use the included self-tapping screw to connect it to your frame or anywhere that's metal and grounded. If you're just using it for your lights, you're all done. These three wires don't need to be connected and we'll have all of our lighting signals at our 7-way, as well as the 4-way, located easily and conveniently at the back of the vehicle.The backup white wire, you can simply tap into the backup lights on your vehicle and then it'll send those signals out to your 7-way. For getting a brake controller set up with your charge line, I would recommend the universal wiring kit for brake controllers. You can pick it up here by using part number 5506. This will come with all the wiring, circuit breakers, butt connectors, and ring terminals you'll need to hook up a brake controller and the remaining wires from our 7-way connector here to the rest of the vehicle.Once you've got it all hooked up, we can test it out to make sure that everything's working using the included tester on the side of our 7-pole connector here. You want to make sure you have your left turn signal, right turn signal, tail lamps, and brake lamps.That completes our look at Curt's 4-Way Adapter to a 7-Way and 4-Way with Test Light.

Customer Reviews

Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps - C57674

Average Customer Rating:  4.7 out of 5 stars   (290 Customer Reviews)

This multi-function, vehicle-end connector converts any 4-way flat, vehicle-end plug to a combination 7-way outlet and 4-pole flat outlet.


I recently had a receiver hitch installed on my 89 Silverado and the wiring was merely zip tied to the safety chain connection. Well that didn't sit well with me. I wanted a more permanent wiring connection point. So I purchased your 4 flat to 4 flat and 7 way plug and installed it. So far so good. The installation turned out perfect and it looks good. The test lights are a great thing as well. I couldn't be happier.

Perfect. The only issue I had was the 4 flat didn’t stay in the bracket but that was easily remedied with a couple of holes and some safety wire. Other than that I’d say u have one of the best setups you could ask for.
Lawrence L - 08/16/2018


I installed this 4 to 7pin adapter with the T-one harness 118449 and the Drawtite hitch on my 2016 Toyota Highlander. I think the install was 1st rate. This adapter allows me to connect either a 4 pin or 7 pin plug. Nice. Very simple to check out the installation with the test lights. Adapter looks rugged and well made. The 4 pin receptacle that slides into the bracket should have better retention though.
Also I provided a picture of the 4 wire cable from the car harness to the adapter as it exits the storage compartment. I removed the grommet/seal. Made an X cut in the center. Forced the cable through it. Made a waterproof seal with RTV.


Very quality product. Well built and easy to install. Had another manufacture's harness on my vehicle and after about a year, it was intermittent. The Curt harness is sealed in the back which is why I choose this one along with the builtin test lights. I would recommend this harness to anyone along with the great service at etrailer! I installed the harness on a 2016 Hyundai Santa Fe Ultimate.


This is the second vehicle I have installed this adapter on. We tow a Coleman popup and another smaller trailer so we need both the 4-pin and 7-pin adapters. The test lamps are great to confirm that you have installed the wiring correctly.


I use both 4 pole flat and 7 pole connections on our trailers so this fit the bill. Here, I welded a bracket to use it on our Dodge Journey.


Install was simple. Plugs in, added my own wires for brake controller and constant 12v. Works 99% great. When trailer is hooked up up, works perfect. Except, when I I unplug the trailer the test lights mess with my brake controller. The LED somehow is still inline with the circuit, well because it is a test light. I snip my blue wire going into the harness and my brake controller works perfectly when I unplug it. Have to switch over to the same adapter harness that does not have the test lights.

I am using a redarc tow pro v2. I get the flashing red light about 10 seconds after disconnecting the plug. In my case the error list this as a faulty ground on the trailer. I don't get it because it is unhooked? Regardless I wired the controller and adapter harness ground all the way to the battery itself. Still didn't change a thing. I even called redarc tech support in Australia. I never did tell them about the test LED's though, maybe if I did they would have went a different direction with the diag. They helped the best they could. I don't fault the person I talked to at all. I would guess the test lights on the adapter to be wired in parallel to work. With that thought, after unplugging the trailer, the brake controller must still be seeing the LED test light. I'm not an electrician/engineer but the small led of a test light, maybe not enough resistance overall to think a trailer was hooked up, but enough to throw a fault. If I was to break/damage the test led for brake, I would bet that it would most likely would work fine as it would cause an open in the circuit.

Thank you for your feedback. We had heard of this happening with the adapter and reached out. There has been a design change with the adapter to eliminate this issue.
-- Etrailer Expert Jenny N - 11/01/2021


Works great, easy to install and fast delivery from E-trailer.


Easy installation and absolutely great unit - works fantastic


Great product! Sturdy and weather-proof connections and wires! Easily installed. Thanks Curt and for an awesome item!


Shipped out very fast and arrived before the estimated arrival date.. install was super easy with the LED test lights.


The bracket was too wide for the OEM hitch and cover on a 2013 Highlander (see photo). I had to grind down part of the the bracket so it would clear the plastic cover. The top two mounting screws did not line up. I had to elongate one of the holes. The 4 pin connector merely slides into the side of the bracket, rather than fitting in like a grommet, so I'll bet it comes out one day. The wiring on the back of the 4 pin connector is visible when looking at the side of the bracket, making for a less than clean look.


Great product I used this to convert my 4-way harness to a 7-way + 4-way harness on my 2011 Toyota Sienna.

Everything went really well. The only very small complaint I had about this product is the length of the white ground wire. It was too short to reach a good grounding point on the frame so I had to go buy some extra wire and connectors to extend it. Make that cable about 3 ft longer, and just provide the ring terminal and this would be a perfect product.

Installing it makes me want to splurge on a tow controller and charge line...

HiI have a toyota sienna 2011 and i want to tow a pop-up camper. Mine has a towing package. The camper is around 2400 lb. in your case do you think a brake controller is necesary?can you tell me What kind of cable do u buy to extend the white ground cable?Di d u buy the no drill tie bracket?
-- comment by: Aldo - 06/27/2014
Aldo. We towed a popup trailer that was little less than that loaded weight without any issue. This was a one time rental for us. We towed up over Vail Pass in Colorado without any issue at all. The engine and transmission on the Sienna could tow a lot more weight, it is limited due to the suspensiontire rating.The only problem we faced is that when hitched we couldnt open the rear door of the sienna due to the trailer jack on the tongue of the trailer.If I was to tow regularly I would invest in a break controller, charge line, and a Weight Distributing Hitch. The main limitation in towing with a sienna is the hitch weight.No I didnt buy the tie bracket. The hitch I purchased 75696 had a built in bracket that this fit on perfectly just had to get a few screws/nuts for it.I just bought some 12 guauge auto wire at autozone.
-- comment by: Daniel S - 06/30/2014


I really liked the idea of having the LEDs to let me know if I was having any problems with the wiring harness, but I did find a problem with it. I installed the wiring harness myself, using the instructions on the website, but after connecting everything I realized that the LED for 12v power is always on. It is not switched by the key, so although an LED should have low draw, this might not be a good idea on a work truck that stays parked for long stretches.

I am still very happy with this adaptor, but I did put back in the plug on my brake controller so I could unplug it when the trailer was not connected, the brake light was on, and I disconnected the continuous 12v. Also, make sure your 4 wire connector is clean or you might have dim lights. Although the LEDs are useful, I found a plug in tester to be more accurate because of the false brake signal I was getting.
Chris H - 05/19/2014


Last project built. Used etrailer for almost all parts, including the 7 pin wiring harness. Friend wants one now so started another one. I will be getting all the parts from etrailer...


Does exactly what I needed it to do. Purchased a trailer with a 7 pin connector, which was an issue as my truck's stock pigtail was a 4 flat. I didn't want to get a straight 7 pin, as my boat trailer is a 4 flat and I didn't like the idea of relying on a separate 4 flat adapter inside the 7 pin connector when I needed to tow the boat. This product has worked flawlessly. Took about 30 minutes worth of work to install on my receiver, mostly to get the bracket installed. There are connections ready to hook up for auxiliary power and electronic trailer brakes. I haven't used these, as my pop up is pretty light for my truck and I don't really need the trailer brakes. The 4 flat side has also worked without issue.


Installed and have camped for one season using this 7-pin connector. Works great. I did make one mistake, I didn't add a relay to break the aux power connection when my vehicle is not running so the aux power LED is always lit. Got a number of comments about that this season. Might have to add a relay...


Worked well, easy to install. Only complaint is that there is no way to turn off test LED's when not trailering. Seems like it would have been simple enough for manufacturer to include on/off switch to deal with this.


I need the ability to pull trailers with both 4 Pole and 7 Pole connections and this adapter did the trick. It's heavy duty and I think the extra few bucks for the Test Lamps was well worth it.


Still works as intended.


lacks installation instructions. Have to have a local garage see if he can figure it out. Product looks good but we will see.

I wanted to reach out to you in regards to your review on the 4 to 7 adapter. I am happy to assist. What is the year, make, and model of your vehicle? Are you also installing a brake controller or just need it for the lights?
-- Etrailer Expert Jenny N - 11/19/2021
We just need it for the lights. The car is a Toyota 2019 Highlander hybrid model XLE.
-- comment by: Emerson - 11/19/2021
Since it is just for the lights then you would plug in your 4 flat into the adapter, mount it to the bumper with the mounting bracket and then ground it using a self-tapping screw to the vehicle frame making sure it is grounded to bare metal. You can then tie up the rest of the wires since you would not need them. If you do not want to mount it to the bumper, you could use mounting bracket part # C57202
Curt No-Drill Bracket for 6-Way or 7-Way Round Trailer Connector Mounting Bracket - Long
to attach it to the hitch. If your 2019 Toyota Highlander does not have a four way flat then you would need part # C56217
Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
-- Etrailer Expert Jenny N - 11/19/2021


Could not have been any easier and all worked the first time. Quality product every thing fit properly with plenty of wire Where needed .


I bought this for my '68 GMC 3/4 ton, which is in really nice shape so I wanted a clean install. The hitch was pretty easy to fit - I had to drill holes in the frame but I knew that going in. I especially liked the built-in bracket for mounting the trailer plug, worked great with a Curt combo 7 pin / 4 pin adapter from eTrailer.

Good product, great seller.


The connector is constantly drawing a small charge from your vehicle battery to show you it is working. In cold weather this can lead to draining your car battery. I had install a switch to shut it off when it's not being used.

The LED test lamp lights draw such a small amount of power that they will not drain the vehicle battery even in cold weather.
-- Etrailer Expert Heather A - 04/13/2021


Best thing I did for my Pop Up camper. It allowed us to use the electric brakes. We do not even notice the trailer back there any more. Only thing is the little red light stays on all the time (like it is supposed to) so people are always letting us know we have a light on.


Great product for a great price, it's worth mentioning though that the 7 blade and 4 blade conections don't mount side by side unless you use the supplied bracket, mounting it through a flat spot on the bumper Wil leave the 4 pin connector hanging behind where you still have to crawl underneath to hook up a small trailer. But the LED lights are absolutely awesome to have and have labled.

Still works great, and the led lights are still the best feature
Daniel - 10/22/2017

Show More Reviews

See what our Experts say about this CURT Trailer Wiring

  • Troubleshooting Brake Output Circuit Shorting Out After it Was Ran In the Fender Well with Snow
    I spoke to my contact at Curt and he informed me that the brake output circuit is attached by a cinch connector at the back of the connector. When I described the situation you were in he said that it very well could have pulled itself out of the connector from the weight of the snow plus you kicking it. You should be able to reconnect it though once you take it apart. I would recommend you reroute the brake output circuit somewhere else that will avoid pinch points and heat like suspension...
    view full answer...
  • Tail/Marker LED Indicator on Curt Trailer Connector Adapter Stays On All the Time
    Since it takes very little power to run an LED light, if there is any draw on the circuit at all it can light up an LED dimly. Whether it is dim or bright one cause of this is a short drawing power even though the vehicle may be turned off. You will want to inspect both the vehicle and trailer side connectors. Clean out any dirt or corrosion on the pins or where the wires attach inside the connectors. This is the likely cause of the problem. Check the wiring on the vehicle leading to...
    view full answer...
  • What do the Codes for the Test Lamps Mean on CURT Adapter 4 Pole to 7 Pole and 4 Pole # C57674
    On the CURT Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps, # C57674, the test light codes are as follows: 12V = 12 volt hot lead BK = output from brake controller (if no brake controller is installed, this light will not light up) BU = reverse lights (if this circuit is not connected on the vehicle it will not light up) RT = Right Turn TM = running lights (tail/marker lights) LT = left turn
    view full answer...
  • Is the 4-way from the Curt Permanently Attached to the Mounting Bracket
    The 4-way of the Curt Adapter 4 Pole to 7 Pole and 4 Pole # C57674 that you referenced can be attached to the mounting bracket of the product, but it can also be removed. So you could attach it to the bracket when not in use so that it does not dangle and interfere with anything and then pull it off the bracket when you plan on towing a trailer with a 4-way connector.
    view full answer...
  • How to Wire Up a Curt Brake Controller on a 2011 Chevy Silverado
    For a color to color application you will run the black wire from the brake controller to the red/black wire from your truck, the white wire from the controller to the white wire of your truck, the red wire from the controller to the light blue/white wire from your truck, the blue wire from your controller to the dark blue controller of your truck. I attached a picture of a chart to make this easier also. I also attached a video of a brake controller being installed on a similar 2011...
    view full answer...
    Image 1 for Image 2 for
  • Troubleshooting LED Lights on the Curt Adapter to 7-Pole and 4-Pole
    On the Curt 4-Pole and 7-Pole Adapter, # C57674, the blinking LED light for the brake may have a short. I recommend having the company who installed the unit to check to make sure that the wire connection is secured. The wire may be loose and grounding out causing the LED to light on the adapter. As for the 12-volt LED, the circuit is wire direct to the battery and is live all the time.
    view full answer...
  • Gauge Wire Used for the Yellow Wire of the Adapter 4 Pole to 7 Pole and 4 Pole C57674
    The yellow wire of the # C57674 that you referenced is 12 gauge. This is the circuit that commonly carries the reverse light circuit.
    view full answer...
  • Troubleshooting Brake Lights that Come On When Trailer Connector is Grounded
    Sounds like your brake light is wired to your 12 volt power source or is shorting out to it and because of that it is illuminating whenever the circuit is complete by connecting the ground. I would inspect the wiring, particularly between the black wire and the stop/turn signal wire that is illuminating for cut or exposed wire and fix as necessary. I attached a couple helpful FAQ articles for you to check out also.
    view full answer...
  • TM Light Stays Lit On Curt Adapter 4 Pole To 7 Pole And 4 Pole With Test Lamps
    I spoke with my contact at Curt about the Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps, part # C57674. They told me that if the vehicle has running lights as so many later model vehicles do, the TM test light will show there is current by lighting up. it sounds as though it is working just fine for you.
    view full answer...
  • Where to Connect the Red Wire of a Brake Controller in a 1995 Ford F-150
    For the red wire of your brake controller you will need to tap into the brake light switch of your 1995 Ford F-150. What you need to do is test the wires of the switch at the brake pedal to determine which of those wires sees voltage when the brakes are applied and none when released. That will be the circuit you attach the red wire of your brake controller to. The brake controller should still power on though without this connection being made. As long as the power wire (black) and ground...
    view full answer...
  • Troubleshooting Trailer Taillights that Stop Working When Brake Pedal is Depressed
    This sounds like a ground issue. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light. Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces. The light grounds should also be attached to clean and corrosion free bare metal...
    view full answer...
  • Should the BK Indicator Light on the Curt Adapter be Lit up While Vehicle is Off and No Trailer
    The BK light indicator on the Adapter 4 Pole to 7 Pole and 4 Pole w/Test Lamps # C57674 that you referenced means that your brake controller is sending power to the pin in the 5 o'clock position. This should only be lit up when you are either coming to a stop with a trailer hooked up or using the manual override lever on your brake controller to send max power to the 7-Way. The only indicator light that should constantly be lit up is the 12V indicator light which is connected to the battery...
    view full answer...
    Image 1 for
  • What Pins of a 7-Way Should have Voltage All the Time
    The 12 volt accessory circuit of a 7-way should be run to the positive post of the vehicle battery through a circuit breaker so that sounds like it is wired up correctly. The back up circuit (if needed) should get run to the reverse light circuit of your 2009 Ford Ranger. It should not be active all the time unless your vehicle is put in reverse or if you wanted a second 12 volt accessory circuit and ran it to the positive post of the battery as well.
    view full answer...
  • Brake Controller Wiring Harness for a 2014 Toyota Tacoma
    Actually the 2014 (as well as the 2015) Toyota Tacoma still use the # 3040-P harness for a Tekonsha brake controller. If you have found a connector that looks different on your 2014 Tacoma then it is not the right connector. The connector you are looking for could be difficult to find if it is not just hanging out. You may have to fish it out from above other wiring harnesses or behind trim panels. If you are using a different brand controller let me know what it is and I can determine...
    view full answer...
  • Does 12V Power Feed on Vehicle 7-Way Remain Active at All Times
    Vehicle 7-way trailer connectors include a 12V auxiliary power feed for the trailer that may remain on at all times, or be controlled by the position of the ignition key. This varies by vehicle make and model and how that circuit was wired. Some people may want that circuit active at all times, depending on their application. You just want to keep in mind that as long as your trailer is plugged in to the vehicle socket anything on the trailer that wants to draw power from the vehicle will...
    view full answer...
  • Both Turn Signals on Trailer Come on When Using Only One of Them
    Start off by checking your connectors to make sure that they are free of debris and do not have any corrosion built up. If all of that looks good then you will want to check all of your grounds to make sure that they are secure and connected to clean, bare-metal surfaces. Any paint or corrosion could cause this. Finally if all of that looks good you need to give your 4-Pin flat connector its own ground. Instead of wiring it to the Curt Adapter # C57674 ground it by itself instead. If...
    view full answer...
  • Does Pollack 7-Way Fit Into Curt 7-Way Connector # C57674
    The Curt 7-way part # C57674 that you referenced does work with a Pollack 7-way as they are both designed to fit the standard 7-ways found on RVs, trailers, etc. The hitch step you mentioned though was discontinued a few years back.
    view full answer...
  • 7-Way Adapter Recommendation for 2000 4Runner for Just Trailer Lighting
    The part # C57674 would be all that you would need. This will plug right into the 4-way of your vehicle and then will allow you to activate just the taillights of your trailer. The extra wires would just need to be taped up out of the way.
    view full answer...
  • Will Indicator Light of Curt 7-Way with Tester Drain Vehicle Battery
    The LED indicator lights of the part # C57674 would not draw enough amperage to kill your vehicle battery. It would take months of inactivity for it's amperage draw to make a difference and and that point the battery would have drained from inactivity.
    view full answer...
  • Options for Converting Factory 4-Way to 7-Way on 2014 Ford F-150
    The Curt Adapter, # C57674, is exactly what you will need to add a 7-way to your 2014 Ford F-150. Installation will be fairly simple, just connect the 4-way on the adapter to the 4-way on your truck and then connect the remaining wires to the corresponding wires on the back of the factory plug. Unfortunately a 7-way connector that will plug directly into the vehicle wiring is not available.
    view full answer...
  • Installing Curt 7-way Trailer Connector Without Connecting Additional Wires
    If you just need a 7-way trailer connector for the sake of connecting to a trailer with a 7-way and not for the additional functions then you can install the Curt # C57674 and either cut off or cap off the extra wires.
    view full answer...
  • Why is 12 Volt Test Light of Curt Adapter With 7-Way Staying On
    It is not surprising that the 12 volt indicator of the Adapter 4 Pole to 7 Pole and 4 Pole with Test Lamps # C57674 even though you are't connected to 12 volt power in your vehicle. You mentioned that you were connected to the battery of the trailer and that when you disconnected the adapter the light went out. The adapter is simply sensing the 12 volt power from the trailer battery, as you mentioned. I have added links to video reviews for you to check out as well if you'd like.
    view full answer...
  • What Does TM Light Refer to on Adapter 4 Pole to 7 Pole and 4 Pole # C57674
    The TM indicator light of the Adapter 4 Pole to 7 Pole and 4 Pole # C57674 that you referenced refers to the trailer running light circuit. This circuit will be on if your tow vehicle has the running lights or headlights on. If not, then there's a short between that circuit and the head light or running light circuit of your vehicle.
    view full answer...
  • What is the Function of the Second Yellow Wire on the Curt Adapter C57674
    The 12V LED indicator light on the Curt Adapter # C57674 that you installed on your 2011 Ford F-150 won't draw enough power to drain your battery as you indicated. The extra yellow wire is actually an auxiliary pin which most people use for the reverse light function. I know it is a little confusing because there already is a yellow wire, but since there are no laws about what wire needs to carry which function this is just the design that Curt decided to go with. Attached is a piece...
    view full answer...
    Image 1 for

< Previous
123. . .8

Do you have a question about this Trailer Wiring?

  • Why

    At we guarantee:
  • Highest quality trailer wiring for the best price.

    Our Lowest Price Pledge ensures you will never overpay for the parts you need.
  • Real product know-how.

    We make sure that the products we sell are what we say they are, and that they work the way they are supposed to work. Get real advice from a real person who has the knowledge and expertise needed to solve your problem.
  • Most detailed, accurate trailer wiring information available.

    Because we take providing accurate product information seriously, we take our own detailed product photos, demo videos and installation videos, as well as verify measurements, instructions, and vehicle fit information.
  • Installations, made easy.

    We love helping people and have the most highly-trained customer service, hands-on experience, step by step videos and installation instructions.
  • Fast shipping.

    Your order is automatically routed to get out of our warehouse and to your door as quickly as possible. Receive free shipping on orders over $99.
  • Personalized service for life.

    We provide one-on-one, personalized service from the ordering process through the life of your product.
  • Trusted since 1946.

    We've been serving customers since our parts store first opened in 1946 and continue to be recognized by our customers, our vendors and third parties for exceptional service.
  • Returns Policy

    Need to return an item? No problem. Please read our Returns Policy for more information.

Info for this part was:

Employee Joe V
Test Fit:
Joe V
Employee Nicholas E
Test Fit:
Nicholas E
Employee Colin H
Test Fit:
Colin H
Employee Andrew S
Test Fit:
Andrew S
Employee Brent H
Test Fit:
Brent H
Employee Mike L
Expert Research:
Mike L
Employee Robert G
Expert Research:
Robert G
Employee Michael H
Expert Research:
Michael H
Employee Jeff D
Expert Research:
Jeff D
Employee Jameson C
Expert Research:
Jameson C
Employee John H
Expert Research:
John H
Employee Adam R
Expert Research:
Adam R
Employee Rachael H
Expert Research:
Rachael H
Employee Jeffrey L
Expert Research:
Jeffrey L
Employee Zack K
Video Edited:
Zack K
Employee Joshua S
Video Edited:
Joshua S
Employee Jacob T
Video Edited:
Jacob T
Employee Chris R
Video Edited:
Chris R
Employee Andrew K
Video by:
Andrew K
Employee Dustin K
Video by:
Dustin K
Employee Alan C
Video by:
Alan C
Employee Zach D
Video by:
Zach D
Employee Adele M
Updated by:
Adele M
Employee Wilson B
Updated by:
Wilson B
Employee Hannah L
Updated by:
Hannah L
Employee Kristina F
Updated by:
Kristina F
Employee Isabelle B
Updated by:
Isabelle B
Employee David F
Installed by:
David F

At we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.

Product Experts Available Now!
Call 1-800-496-5010