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Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed
Curt Custom Wiring Adapter for Trailer Brake Controllers - Dual Plug In

Part Numbers: C51120,C51436


Our Price: $53.73

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Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed Automatic Leveling C51120
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Product Images

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Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed Automatic Leveling C51120
Brake Controller C51120 - Digital Display - Curt
Curt Brake Controller - C51120
Brake Controller C51120 - Under Dash Mount - Curt
C51120 - Digital Display Curt Brake Controller
C51120 - 360 Degrees Curt Time Delayed Controller
Curt Time Delayed Controller - C51120
Curt Time Delayed Controller - C51120
Curt Electric Brake Controller - C51120
Brake Controller C51120 - Automatic Leveling - Curt
Accessories and Parts C51436 - Plugs into Brake Controller - Curt
Curt Custom Wiring Adapter for Trailer Brake Controllers - Dual Plug In Vehicle Specific C51436
Curt Accessories and Parts - C51436
Curt Brake Controller - C51436
Curt Brake Controller - C51436

In Use/Installed

Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed Up to 4 Axles C51120 on 2008 Chevrolet Silverado
Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed Digital Display C51120 on 2008 Chevrolet Silverado
C51120 - 360 Degrees Curt Brake Controller on 2008 Chevrolet Silverado
Curt Time Delayed Controller - C51120 on 2008 Chevrolet Silverado
Curt Time Delayed Controller - C51120 on 2008 Chevrolet Silverado

Customer Photos

Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed
part number: C51120

Electronic controller activates electric trailer brakes with a preset intensity when you apply the brakes in your vehicle. Power output and braking aggressiveness are easily adjustable. Includes easy-to-read digital display and manual override.


  • Brake controller activates trailer brakes with preset intensity
    • Signal is sent to trailer brakes when tow vehicle's brakes are activated
  • Adjustable, thumbwheel power output control lets you determine the amount of braking force
    • Set to maximum when you travel through hilly terrain with a fully loaded trailer
    • Back off the power output when you tow a lightweight trailer
  • Sync setting lets you adjust the aggressiveness with which the brakes are activated
    • Get full power output faster by moving slide-bar switch forward to increase activation speed
    • Achieve smoother braking by moving switch in opposite direction to supply power gradually
  • Easy-to-read digital display communicates brake force output, sync setting, and error codes
  • Self-diagnostics function monitors trailer connection and checks for shorts
  • Built-in, slide-bar manual override
  • Quick and easy installation
    • No need to mount level like proportional brake controllers
    • Mounting bracket and hardware included
    • Plug-in, vehicle-specific brake control adapter (sold separately) can be used for certain applications to reduce installation time


  • Application: trailers with up to 4 axles (8 brake assemblies)
    • Designed for use with electric brakes only
  • Limited lifetime warranty

Time-Delayed Braking

The Discovery applies your trailer's brakes when the brake pedal in your tow vehicle is engaged. Every time you apply the brakes in your vehicle, a signal is sent - via the brake switch - to the Discovery. The controller then sends power out to your trailer brakes to activate them with an intensity set by you, at a rate determined by you. Both the amount of braking power (output) and rate of application (sync) can be adjusted to suit your preference, the road conditions, type of trailer, and size of the load. To determine which levels are best for your application, you must test out your towing setup and choose what feels best.

A time-delay controller is so named because there is a delay between the time that you initially apply the brakes in your tow vehicle and the time that the controller reaches maximum power output. Unlike a proportional brake controller, which activates your trailer's brakes based on the deceleration of your tow vehicle, the Discovery sends power out in the same way, with the same gradual delay, no matter the braking situation. Although this delay always exists, it can be adjusted by changing the sync setting.

Built-In Controls for Adjustable Power

Curt Discovery Controls and Components

The above diagram shows the controls and components of the Curt Discovery trailer brake controller.

  1. Digital display
  2. Power output control
  3. Sync control
  4. Slide-bar manual override

Output Control

During the initial setup process, use the thumbwheel control on top of the Discovery to adjust the output. The output control lets you set the maximum amount of power that will be applied to your trailer's brakes. Typically, the output is only readjusted when you experience changing road conditions or if you switch over from a heavy, loaded trailer to a much lighter, empty trailer, or vice versa. To get more power to your brakes, rotate the switch to the right. To decrease the power output, move it to the left. The output setting will appear on the digital display when you press the brake pedal or activate the manual override. This setting ranges from 0 to 10, with 10 indicating maximum output.

Sync Setting

To adjust the aggressiveness of your trailer's braking action, use the slide-bar control on the side of the Discovery to change the sync setting. If you want to reach maximum power output faster, move the switch forward. To get smoother braking action, slide the switch backward, thus supplying power to the trailer brakes more gradually. You can alter the sync setting to suit your driving preferences or to improve handling based on changing road conditions or varied trailer loads. The digital display will only show the sync setting as you adjust it.

Quick, Simple Installation

Because inertia plays no role in the functioning of this controller, you do not have to mount the unit at any particular angle. As a result, mounting options are limitless, so long as you can still easily access the controller.

Installation of the Discovery requires that you either purchase a custom wiring adapter designed to plug into the controller or that you hardwire the controller directly into your vehicle. To hardwire the Discovery, you must remove the plug at the end of the integrated wiring harness.

Installation Accessories

For easier installation, a vehicle-specific wiring adapter (sold separately) is available for most newer trucks and SUVs. One end of the custom adapter plugs into your vehicle, and the other end plugs into the controller - no hardwiring required.

Note: If a custom brake control wiring adapter is not available for your vehicle, one of the following will be required:

20-Amp circuit breaker (9506P - sold separately) for 2- to 4-brake applications

30-Amp circuit breaker (38630 - sold separately) for 6- to 8-brake applications

See also etrailer.com's exclusive 7- and 4-way brake control installation kit (ETBC7 - sold separately) if you don't already have a 7-way plug at the back of your vehicle.

51120 Curt Discovery Time Delay Trailer Brake Control

Curt Custom Wiring Adapter for Trailer Brake Controllers - Dual Plug In
part number: C51436

Install your Curt electric trailer brake controller quickly and easily with this custom wiring adapter. Simply plug one end of the adapter into your brake controller and then plug the other end into the built-in port behind your vehicle's dash.


  • Plug-in wiring adapter allows for quick, simple installation of your electric trailer brake controller
  • No cutting or splicing required
    • Custom connector end plugs into the built-in port behind the dash of your vehicle
    • Other end plugs into the back of your electric brake controller
  • Compatible with time-delayed and proportional brake controllers from Curt
    • Brake controller must have built-in plug for adapter to connect - will not work on controllers with pigtail wiring harnesses
  • 2' Long, 12-gauge wires have protective covering to deter damage
  • Limited 1-year warranty

Installation of Curt Brake Controller Adapter

To install your Curt electric brake controller, you need to connect the wiring of the controller to your vehicle. Certain auto manufacturers offer pre-wired options, typically known as tow packages, wherein wiring is run for you from the dash to the trailer connector on the back of your vehicle. When this is done, a port is installed at your dash so that you can easily plug in a brake controller.

This adapter plugs into the port on your vehicle's built-in brake control wiring harness. For most applications, this harness is located behind the dash.

No hardwiring is required to install this adapter. After you plug it into the factory port, you simply plug the other end of the adapter directly into your electric trailer brake controller. Because there are no wires to connect, installation is not permanent. You can unplug and remove your brake controller at any time to transfer it to another vehicle or securely stow it away.

51436 Curt Quick Plug Brake Control Adaptor Harness

Video of Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed

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

Video Transcript for Curt Brake Controller C51120 Review

Today we're going to take a look at the Curt Discovery Trailer Brake Controller number C51120. This time delayed brake controller activates trailer brakes with a preset intensity. The signal is sent to the trailer brakes when the tow vehicle's brakes are activated.It has an adjustable thumb wheel power output that allows you to determine the amount of breaking force you would set to the maximum when you travel through a more hilly terrain with a fully loaded trailer and you would back off the power output when you're towing a smaller more lightweight trailer.It also features a sink switch here on the side. It allows you to adjust the aggressiveness of the brakes. If you want it full power in this position right here. It will increase the activation speed of the brakes and you would move it back in the opposite direction to achieve a smoother braking by supplying the power more gradually.

It has an easy to read digital display that communicates brake force output, sink setting and air codes and we'll attach this to a power supply in just a moment so you can see that a little better. Self-diagnostics function monitors the trailer connection and checks for shorts. It has a built in slide bar emergency manual override and again we'll discuss that more in just a moment. It has also has a quick and easy installation. It comes with the mounting bracket right here.

The screws to attach the bracket to the controller as well as a quick reference card if you have any questions. One of the differences between the time delay brake controller and a proportional brake controller is there's no need to mount this one level the way you would a proportional controller.You can mount it up, down, side to side, as long as you can see the digital display you're good to go. This application is for trailers up to four axles or eight brake assemblies. It's designed for use with electric brakes only and it does have a limited lifetime warranty. Now we're going to attach it to our power supply and the wiring harness that we're using here is the Curt Universal Wiring Adapter for Curt Trailer Brake Controllers, number C51515.

This particular harness ends in a pigtail and it is intended for vehicles who do not come with a factory installed brake controller port. Now when you hit the brake you will be able to see the digital display and say right here we'll use our output knob here. You can go from zero to ten and we'll set that at five for right now and over here our sink all the way to nine and then slide it back to zero. We will put that at five as well. When we talk about our emergency manual override say youre in traffic and somebody cuts you off and you have to hit the brakes really quick what you would do is hitch your emergency manual override and instead of the normal amount of time it would take for the trailer brakes to brake this removes the time delay function and the maximum output that you had preset it goes to the brakes immediately to help slow you down to prevent any accidents.

That should just about do it for our Curt Discovery Trailer Brake Controller number C51120.

Customer Reviews

Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed - C51120

Curt Custom Wiring Adapter for Trailer Brake Controllers - Dual Plug In - C51436

Average Customer Rating:  4.8 out of 5 stars   (213 Customer Reviews)

Electronic controller activates electric trailer brakes with a preset intensity when you apply the brakes in your vehicle. Power output and braking aggressiveness are easily adjustable. Includes easy-to-read digital display and manual override. Install your Curt electric trailer brake controller quickly and easily with this custom wiring adapter. Simply plug one end of the adapter into your brake controller and then plug the other end into the built-in port behind your vehicle's dash.

- C51120

by: Bob R02/05/2016

I bought a new car dolly with electric brakes to pull with our motorhome ( Fleetwood FlAIR 2001 ) as all states require brakes on trailers at all different weight levels. I called E trailer and spoke with Danna and after talking with her about different models I choose the C51120 time delay control, as it can be adjusted to work well with the tow vehicle . I received the control with in 3 days of the order and went to put it in and found under the dash wire a harness by Fleetwood which told where each wire on the controller went on the harness. I was able to hook it up sitting in the drivers seat. Completed the hook up and started to test the operation, to find I was not getting the proper readings. I talked with Tom and he said he would bench test a like control and report back to me, at 6 pm he left a message on our phone that he believed the problem was along the blue wire to the trailer on the tow vehicle . I started at the back of the, motorhome and moved forward testing for a brake signal, I found that the butt connector had pulled apart and was not getting current to the plug in at rear of coach. Hooked it back together and re taped the wires and it works like a charm. I want to thank all off you for the prompt and knowledgeable service, I would recommend E trailer to anyone who wants to deal with a great staff and company Thank you 237064


I used this controller to pull ma car dolly to AZ and back through all the mountains and it worked GREAT I am very happy with how it worked Great product

Bob R - 02/04/2017


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by: George D10/17/2015

the brake controller with all the wiring plus the 7 pin plug was better than i thought . it even has great instructions and easy to read. the price was good . the 7 pin plug even has the 4 pin connector mounted in with it very glad that i bought it is everything that you need to make it work . everything about it is excellent very glad that i found it here at a good price . even fast shipping . again thanks for good product 230172


Use it for pulling camper works great even a good price fast shipping . Its been a year and still working great.

George D - 10/16/2016


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by: Bobby04/30/2016

Easy to install and Thanks for the help. 247727



Bobby - 04/30/2017


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by: Tommy J.01/31/2014

Adapted Curt brake controller for my 2014 Ford F150 STX without any problems. Just find your Ford brake control connector behind the coin slot on the left side of the dash and plug it in. 115344


After a year of using the Curt brake controller it has been by far the best one of several I have used and installed. i highly recommend the controller.

Tommy J - 01/31/2015


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by: Randy G01/04/2014

This is an outstanding product - exactly as described. I installed it into my 2005 Ford F150 XLT Extended Cab. Took longer for me to decide where to put it than the actual installation, which took about 3 minutes. My truck had the tow package so the harness - which was included - was an exact match to my truck's harness plug on the right side of the dash in the driver's area. Extremely satisfied. 111895


It is still working well I used the Brake Controller a week ago and still no problems. Works exactly as described. Great product!

Randy G - 01/05/2015


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by: Raymond L.05/30/2015

Awesome product. Easy to install and adjust to your liking. Use in combination with the custom wiring adapter for your vehicle and you have a product that can't go wrong! 198827


This product has worked flawlessly this past year. Great product and will definitely deal with etrailer for all my trailer needs

Raymond L - 05/29/2016


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by: Mark Mason03/19/2014

I always get excellent products and advice from Etrailer will keep comming back 121339


Great I rarly have to recalibrate the brakes and my wife will now tow with confadence

Mark M - 03/19/2015


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by: J.C. from Bay City02/24/2014

Ordered a brake control and an inline circuit breaker on Feb 11th and shipped the same day. I chose the least expensive shipping option (my bad). A combination of UPS/US Post Office, or so I was told after calling to find out where my shipment was. Tracking info said delivery by the 15th. When it didn't show I called etrailer and was told the post office had it and it was out for delivery...2 days later I finally received it (Feb 20th). I ordered a hitch a couple of weeks prior and received it in 2 days. A 49lb hitch vs a 1lb (maybe) package. Not etrailers fault but I can see why the post office is going broke with service like that! 117375

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by: Adam S.06/17/2016

Trailer Brake Assist works as advertised. Installation was challenging but the how-to video and instructions helped. Hardest part was routing the wires without our 2006 Honda Pilot on a lift. Once it was installed I hooked up our trailer and took it to a large parking lot close by to test and adjust the module. I put my brakes on when we first got there and the trailer screeched to a halt, letting me know it was working well! I adjusted it to the recommended setting and it's worked great since. Makes it especially comforting coming down out of the Sierras. I highly recommend trailer.com for all your towing needs. 262275

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by: Patrick T.01/23/2014

This controller work great in my 2008 Tundra, and is very easy to set up and adjust. 114575


Still working great no problems

Patrick T - 01/23/2015


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by: Justin08/02/2016

After reading the reviews of this product I decided to give it a try myself, with a great price. When I received it within a week along with the plug and play 7 prong trailer hitch adapter, I realized I was missing something. The plug and play adapter for this product. It showed me it when I was buying and for what ever reason I didn't have the option to add it as well. It was very easy to install, like I said plug and play. The problem is it does not work. followed all the directions, double checked everything I just don't have a signal to the trailer from the break controller. Good luck 278660

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by: Patrick03/12/2017

I haven't thought about those products since the day I installed them. That's because I haven't had a reason to think about them again. They have worked perfectly since I bought them. Not only that but, your price, if I remember correctly, was as good as or better than anyone else's. Your website made my purchase easy and I can't imagine that I would buy anything that you sell from anyone else. Great product (I know your company didn't build it but,....) no hassle, quick delivery, and great service. All around good experience. Thank you for checking (great customer service). 355662

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by: Edward D07/20/2016

Bought brake controller and custom wiring harness for my 09 Dodge Ram. I've had several Curt brake controllers in other trucks with good results. For the price they are good quality controllers. I've had both delayed time and proportional controllers, both do the job. I prefer delayed time on 1/2 ton trucks since you can set the controller to have trailer brakes apply harder. Installation is very simple, decide there's you want the controller, have 2 screws to hold bracket and 2 screws to secure controller. Took about 5 minutes to install. 274320

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by: Paul07/05/2018

This Curt Discover controller works great. Super easy to install if you get the pigtail for your model truck. I especially like the fact that you can install the bracket under the dash on my new 2018 Silverado using factory screw under the dash. No drilling required. As always wonderful pricing and delivery from E-Trailer. 533806

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by: Ty F.01/18/2018

Less than 1 yr after installing on a 2017 F250, controller quit working right. It would surge brake to some high number like 7 (10 being max) regardless of the controller setting which would lock up trailer brakes. Next time it would only allow a setting of 2.5 or 7.5... nothing else. Next time it would do something different. Called Curt who recommended unplugging it for awhile. Worked for awhile then started acting up again. They're going to send me a replacement. Tbd if replacement will be better. 468124

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by: Mark A.11/18/2013

Etrailer provided outstanding information regarding the technical details of the product along with easy to understand installation instructions. The brake controller provided a cost effective solution for my basic requirements. The installation was a "snap", the only time consuming task was determining the optimal location/position install the brake controller. Item was installed in a 2013 Ford F150 and I use it on a dual axle trailer for hauling a compact Kubota tractor. 107754

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by: 2012 ford F15- trailer brake06/08/2016

Excellent - no hesitation in making that evaluation I bought a brake controller, interface cable for the F150, and the 7 pin plug that goes on the back bumper. All items are great quality. Parts arrived as expected with shipping as paid for. I am installing the equipment, but don't have any issues. There were no installation instructions, however these are available on line line detail. I do not expect any operational probems but am a few days from making that test. 258882

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by: Chris04/28/2018

Not too thrilled with this one. Three main issues listed in increasing order of magnitude. 1. One of the segments on the display died shortly after installing. 2. The adjustment wheel is very crude and hard to dial in. 3. This one is the killer, if you start by manually applying the brakes using the slider, and then put your foot on the brake pedal, and then release the lever, the BRAKES GO FULL LOCK! That's a design flaw in the circuit. 501648

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by: Drew V.10/10/2016

Installed the Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed - C51120 in our 1982 GMC 1-ton dually to activate the brakes on our Forest River Sandpiper Sport SP34T 34' triple axle toyhauler travel trailer... The Curt Discovery Trailer Brake Controller installed easily, adjustment was fairly painless and it performed flawlessly on a recent 600 mile trip. We would definitely recommend this product and etrailer.com! 305035


After 1 year we are still completely satisfied!

Drew V - 10/10/2017


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by: Bill12/30/2013

This is a very small brake controller unit. I had to find the right spot to mount so my knees didn't bump it when I got in and out of the truck. Once the perfect spot was found, the installation was a snap. I used the correct wiring harness to make installation easy. Just snap into back of controller and then into the truck's brake controller wiring harness in the back of dash. It was the simplest install I have ever used. Thanks!!!! 111474

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by: Dustin09/18/2013

I purchased this item with the premade connection wire for my 2010 Dodge Ram with 7 way trailer wiring adapter. I had this installed in less than 12 minutes! Plug the harness in and mount it you are done! Shipping was super fast had my item in 3 days. The best part is I can remove this when I am not towing my RV so that I keep the stock appearance of my truck. Best online buying experience ever! 100495

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by: Dave C05/11/2017

The 1st brake control recommended by the associate was not compatible with my vehicle. When I called in the person I talked with discussed my problem with a tech and discovered that my vehicle needed another type. They immediately sent me the other brake control with a email to print out the return prepaid shipping label. You can not ask for better customer service 379105

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by: Rock W.07/29/2013

I chose this brake controller because it was like one I had before so no learning curve needed. Plus I didn't want to mess with extra install concerns of the proportional type controllers. With the video install tips the shade tree mechanic is back in action. With the yr/make/model suggested cable, hook up was a breeze. Ready to do some camping. Thanks etrailer 92116

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by: Tacoma Stan09/11/2016

Fit nicely under the dash on the left side. Also installed a 7/4 pin connector in the bumper, replacing the blank plug from the factory(etrailer p/n HM40975-11998) 293471

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by: Jim S.01/15/2018

This pigtail that Dan T. with e-trailer help me get order an shipped worked perfectly. It was a custom fit for 2016 F-150 w/ no tow pkg and a Curt 51120 brake controller. This will almost complete my conversion of my truck that had no tow pkg. In the end it will help my daughter tow her Shooting S barrel horse safely to the shows. Thank you Dan T. 467325

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by: Sarge05/30/2017

Simple to use and was amazing! It hooked up in maybe 15 minutes using the specific wiring harness. (That was reading the directions too) It made a huge difference. When breaking I only had to press down on the pedal 1/3 of the way to stop my camper. I didn't have the setting that high either. Great investment. I should have gotten it earlier!! 386425

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by: Loren C.06/06/2016

Super fast delivery. Product was just like advertised plugged it in and mounted it and pulled my camper that weekend and it worked perfectly. The item description was very thorough and eliminated buyer mistakes. Order process simple and secure. Definitely would use E trailer again in the future and would highly recommend them to anyone. Thanks. 258339

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by: Les F02/20/2017

Dealing with etrailer was a good experience. Shipping was great and everything I ordered was in the package. Having just received the package, I haven't installed it yet but I am sure it will be just what I need. I will certainly deal with etrailer again when the need arises. Thanks etrailer for making my shopping experience hassle free. 343758

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by: e whitestone12/03/2013

Much, Much better than the proportional type I had before. The proportional types have to be mounted level. This Curt solid-state digital never needs to be level, in fact it could be mounted upside down and still work. No problem finding a place to mount, since it doesn't have to be level. A great price at etrailer makes it that much better. 109008

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by: David C.05/17/2014

I purchased this controller for a 2006 4 horse stock trailer & a 2006 Dodge Ram 2500 pick-up truck. The installation video from etrailer was very informative & the instruction from the product was very through. I was able to attached the controller & tested it within one hour. I've towed with the trailer since then & it's working great. 131087

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by: Mike11/04/2014

Good quality brake controller for my needs and although I had some issues installing it, etrailer was right there, they helped me troubleshoot my problem and it ended up being a fuse that was not installed apparently by Honda for the ebrake. I popped the fuse in and walah the controller worked perfectly. Thanks Etrailer!! 159127

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by: Tracy W06/24/2017

Easy to install. I bought this model to replace a old one that was already in the truck but was not working. Works good 398529

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by: paul t.09/29/2016

great price and great brake controller this is the 5th or 6th time we have ordered from etrailer and we will be ordering from them again as we have had great prices and fast shipping from there products and them. thank you etrailer for keeping the prices reasonable. from --savannah`s secret gardens 301430

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by: Gar102/27/2015

Product came on time and connector was correct for my vehicle. Controller is small and blends in with vehicle interior. I like the digital readout but the adjustment range is a bit difficult to get right, hopefully I will find the sweet spot between the power and the sync. For the price I like it. 176409

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by: Dave C04/09/2014

With the factory adapter the total installation took 5 minutes including a fight with a tangled extension cord. Worked awesome. Towed a 8500lb load up and down the Appalachian range without any worries. Thanks again for the fast shipping, awesome product and great customer service. 124394

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by: Cynthia07/14/2018

The controller was easy to install. It works exactly as it should at a very good price. Costumer service is excellent. The first controller we received was broken. A quick phone call and two days later a new controller. Would definitely order from this company again. 541795

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by: Andrew12/26/2013

I just received my Curt new brake controller and Etrailer truck brake harness. The package arrived promptly - earlier than expected. The harness kit has everything I need and looks like it is well made. Can't wait to get it all installed and try it out. 111247

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by: TPS09/27/2017

Plugged into the vehicle and hooked up the brake controller, which indicated it was correctly installed. Haven't had the opportunity to test with a trailer, but should work fine. Great follow-up emails advising order received, shipped and delivered. 436835

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by: Max04/11/2015

Made install easy. I ran my own 12 ga wire to 7 pin connector for trailer brakes. I couldnt find the fuse and or relay needed for my 2011 F150 to complete factory circuit. I NEEDED the trailer the next day with a 3,000 lb tractor on it. Worked well. 184737

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by: bill mussell11/22/2016

Brake controller arrived in good time and well packaged. I highly recommend this seller. I won't be installing this for a few months but ever thing looks great. I will be using this on my 2006 ford pick up and towing my 27 ft. travel trailer.BM. 318990

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by: Erik O.08/05/2013

So far so good. Product seems well made. Installation was a breeze. 5-10 mins. Ordering was simple. My Order was upgraded to faster shipping at no additional charge! Fantastic company! Will be ordering from etrailer.com in the future! 93288

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by: Kyle c.04/09/2016

I love this brake controller. It has worked flawlessly since the day I installed it I would definitely buy this unit again. The staff was great and help me troubleshoot. I love that you can adjust it on the Fly depending on the load 243551

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by: Jared H.06/25/2013

Great product for the price. This was my first brake controller and it was very easy to setup and mount. I bought the adapter cable for my truck as well and it made it even easier. For the price you cannot go wrong with this. 86013

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by: Greg M.06/21/2016

Installed on my Dodge Ram 1500'l after work today, with the adapter it was easy as pie. This unit was out of stock when I ordered, so delivery took a little longer than usual, but I have no issues with the product. 263492

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by: Mike N.05/18/2015

Installed and worked as advertised. I would have given it an excellent rating but I think the braking adjustment wheel is a bit finicky, it takes a little finesse sometimes to get it set exactly how you want. 194052

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by: Jaime H.11/25/2016

Product is good quality, I made and error in ordering it, so I am waiting for the correct part. Service over the phone was great too! Thank you for your help in ordering the right Brake Controller Adapter. 319477

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by: Robert B.08/29/2017

I have had MANY braked controllers and this one is the best. Always remember when going from 2 axles to 3, you must match the proper controller. Curt is the best. 5 stars for Curt and etrailer. RB 426327

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by: Dan02/21/2016

very good kit . nothing else needed .love the 7 way plug . very well made . brake controller is very good .like the ability to bench test it before install. very happy with all material and Etrailer . 238373

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by: David G.07/07/2016

Product was delivered as scheduled. Easy installation and works great. E-trailer made it easy to order and provided outstanding customer service. Would recommend them for any trailer related needs. 268879

Show More Reviews

Ask the Experts about this Brake Controller
Do you have a question about this Brake Controller?

  • Brake Controller Installation on 2011 Toyota Tundra
  • If your 2011 Tundra has the factory tow package, which includes the factory installed 7-way trailer connector on the rear bumper, it will be equipped with the tow package plug under the dash, as shown in the photo I've edited for you. Some models with the factory 4-pole (or 4-pin) trailer connector will also have the plug under the dash, you'll need to look for a white plug located above and to the left of the emergency brake pedal, above the toe kick. Occasionally, the plug will be located
    view full answer...

  • Brake Controller Install in 2014 GMC Sierra
  • The install procedure will depend on if you have a 1500 or a 2500/3500 Series. If your Sierra is a 1500 model, you will need a brake controller wiring adapter harness, part # C51451. The 2500 and 3500 series would have the tow package wiring that sits above where the driver's left knee sits. If you click the video link I've provided, you can see a controller being installed in a 2014 GMC Sierra 1500. The FAQ link I provided shows how to install a controller in the 2500/3500 model. The
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  • Troubleshooting Brake Controller that Flashes When Connected to Trailer
  • It sounds like the problem is corrosion on the trailer 7-way brake output circuit which is causing the controller to only show an intermittent connection. Try cleaning off this pin on the 7-way with some fine grit sandpaper. Testing the brake controller is fairly easy. Sever the blue brake output wire near the brake controller leaving enough room to reconnect it and then apply the manual slide. Using a circuit tester like part # PTW2993, you should get output to the controller side of
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  • Troubleshooting Curt # C51120 Discovery Brake Controller Showing Flashing Decimal Point on Display
  • What you're describing sounds like it could either be an interruption in the trailer brake voltage output circuit, somewhere between the controller and the trailer brakes, or you could have a defective controller. Use a circuit tester with an incandescent bulb, like part # 40376 and use the probe to pierce the insulation of the blue output wire exiting the rear of the controller and ground the alligator clip. Apply the brake pedal. If the load provided by the tester causes the display
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  • Curt Discovery Brake Controller Shows OL Error When Trailer is Connected
  • It is possible that it is a simple wiring issue that is causing the errors on your Curt Discovery brake controller # C51120. On your 2010 Chevy Silverado, there is a tow package wire bundle under the dash to wire in a brake controller. The tow package red goes to brake controller black. White goes to white, blue to blue, and the light blue or orange wire on the truck goes to the brake controller red wire. The OL indicates an overload and if all of the connections at the brake controller
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  • Curt Brake Controller and Wiring Harness for a 2015 Ford F-150
  • For a Curt Discovery brake controller # C51120 you will need wiring harness # C51436 for your 2015 Ford F-150. I have linked video reviews for both parts for you.
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  • Troubleshooting Flashing 0.0 Error Message on Curt Discovery Brake Controller # C51120
  • The troubleshooting guide included in the instructions for the Curt Discovery Brake Controller # C51120 that you referenced does not include this particular display issue, a flashing 0.0, among the possible display messages. My technical contact at Curt has never seen this particular message displayed on a Discovery brake controller. He suggested that either the display is malfunctioning or the controller is bad. Since your brakes are not engaging when you press the pedal with the trailer
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  • Brake Controller Installation Harness Recommendation for a 2015 Chevy Suburban
  • Yes, there is a port under the dash of your 2015 Chevy Suburban that will allow for a painless installation of a brake controller that won't require splicing. The harness to go along with the Curt Brake Controller part # C51120 that you referenced is the part # C51452. If you went with our most popular brake controller, the P2 part # 90885 you would only need the harness part # 3016. See the install video I attached.
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  • Installing Curt Discovery Brake Controller # C51120 on 1988 Ford F150
  • To hardwire the # C51120 Curt Brake Controller, you can either cut off the existing plug on its wiring harness or use the universal pigtail, part # C51515. The universal pigtail would provide an easy way to quickly disconnect the brake controller, should it become necessary. You would then use our Brake Controller Installation Kit, part # ETBC7. If you do not already have a functional 4-pole trailer connector you would also need to install one using part # 118316. The install kit includes
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  • Curt Discovery Brake Controller Is Only Showing A Dot When Engaging Manual Override
  • The Curt Discovery Trailer Brake Controller, # C51120, should show only the decimal point dot when the controller is activated and a trailer is not connected. If it shows the dot all the time, the red wire is connected to the wrong side of the stop light switch or the wrong switch completely like the cruise control. If you have only the decimal point when the trailer is connected, the usual cause is that the brake controller does not sense the trailer brakes. This could be due to corrosion
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  • Issues with Brakes Not Activating with Curt Discovery Brake Controller on 2015 Ram 1500
  • I spoke with my contact at Curt about the issues you and other customers have experienced with their Curt Discovery Brake Controllers # C51120 and newer model Ram trucks. The problem stems from a low voltage output on the stoplight wire on the truck. The Discovery requires 12 volts from the stop light wire in order to recognize the signal and activate the trailer brakes. Curt has found that the newer Ram trucks often have less than 12 volts at the stop light wire when the brake pedal
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  • Curt Discovery Brake Control Flashing 0.0 Troubleshooting
  • The troubleshooting guide included in the instructions for the Curt Discovery Brake Controller # C51120 that you referenced does not include this particular display issue, a flashing 0.0, among the possible display messages. My technical contact at Curt has never seen this particular message displayed on a Discovery brake controller. He suggested that either the display is malfunctioning or the controller is bad. Since your brakes are not engaging when you press the pedal with the trailer
    view full answer...

  • Troubleshooting Curt Discovery Trailer Brake Controller # C51120 Installed in 2002 Chevrolet Tahoe
  • Thank you for your recent purchases from etrailer. I would like to suggest some additional testing before you return the Curt Discovery Trailer Brake Controller # C51120. This will help isolate the problem and confirm whether the unit is indeed defective. The code OL indicates that the controller has sensed an overload condition. Disconnect the trailer from the Tahoe. Apply your grounded tester to the pins at the 5-o-clock and 7-o-clock positions on the Tahoe 7-way, as shown on the
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  • How to Find and Access the Brake Light Switch Wire on a 2015 Toyota Highlander for Brake Controller
  • If you check out the video I attached you will see how we installed a brake controller in a very similar 2014 Toyota Highlander as your 2015 model. We had to remove the lower dash panel (13:00 mark of the video), to make accessing the green wire possible. The kit used for the install in the video is the part # ETBC7.
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  • Curt Discovery Trailer Brake Controller # C51120 Displays Only a Red Dot After Installation
  • If your Curt Discovery Trailer Brake Controller # C51120 displays only a red dot when you do NOT have a trailer connected then this indicates that the controller's red (input signal) wire is connected to the wrong side of the brake light switch. This red wire should connect to the COLD side of the switch that has power only when you press the brake pedal. If your Discovery displays the red dot when you DO have a trailer connected then this usually indicates a problem in the trailer brake
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  • Installing a Brake Controller in a 2009 Chevy Suburban
  • The 2009 Chevy Suburban does not have a port to plug in a brake controller which is the same as the trucks of the same year. But it does have the tow package wire bundle up under the dash, to the left of the steering column, held together with a white tag. Pull the wire bundle out to wire in a brake controller. With Curt brake controller # C51120 you will also need pigtail # C51515. Then you can make the following connections: Vehicle red/black wire to controller black wire for 12
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  • Wiring Curt Brake Controller # C51120 in 2002 GMC Sierra 1500
  • Based on your description of the problem with your Curt Discovery # C51120 Time Delayed Brake Controller one cause could be a mis-wired plug-and-play harness. Please refer to the photo provided which shows how the vehicle side of the harness should be wired. For reference I have also linked a help article concerning brake controller installations in GMC trucks. The connector should be pinned out with the four wires as shown in the provided photo. If the red wire is connected to a different
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  • Troubleshooting Flashing Display of the Curt Discovery Brake Controller part # C51120
  • The flashing O.L. message with the Curt Discovery Brake Controller part # C51120 when there is no trailer connected indicates that there is a short somewhere on the brake output circuit. I would check all the connections you made on the blue wire from the controller and then also check the trailer connector at the rear of the vehicle looking for any exposed wire or corrosion and fix as necessary. If it only flashes O.L. when the trailer is connected the problem is the same as above but
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  • Which Brake Pedal Stoplight Switch Does Red Brake Controller Wire Connect to on 2013 Ford Escape
  • The second generation Escape (2008-2012) used a purple and white wire for the stoplight switch, but I could find no information about your 3rd generation Escape. The best way to find the correct wire is to use a circuit tester like part # 40376 and test each of the wires. The wire that only goes hot when the brake pedal is pressed (not with the headlights or turn signals) is the wire you want to tap that red brake controller wire into.
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  • Hardwiring in a 7-Way Trailer Connector and Brake Controller on a 2018 Ford F-150 w/Factory 4-Way
  • I did some checking and right now, in order to add a 7-Way trailer connector to your 2018 Ford F-150, you will need to use our hardwire kit # ETBC7. The factory brake controller wiring harness might be in place but if it is for sure and if that means you can install the Ford brake controller I cannot answer. I am sure you can though because I know in other Ford F-150s you can. Or you could install an aftermarket brake controller using wiring harness # 22292 and a Tekonsha brake controller.
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  • Which Curt Brake Controller Adapter Fits a 2015 Ford F-150
  • The Curt adapter, part # C51436, fits your 2015 Ford F-150. It plugs into the factory connector under your truck's dash and fits most Curt brake controllers, like the Venturer part # C51110. I've linked a video of a controller being installed into a 2013 F-150 using the # C51436 adapter.
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Info for these parts were:

Edited by:
Leah B
Expert Research:
Jackie C
Expert Research:
Michael L
Written by:
Lindsey S
Expert Research:
Michael H
Expert Research:
Jameson C
Video Edited:
Joshua S
Test Fit:
Nicholas E
Expert Research:
John H
Updated by:
Adele M
Video Edited:
Andrew L
Expert Research:
Adam R
Video Edited:
Dustin K
Photos by:
Jim W
Test Fit:
Shane T
Expert Research:
Jeffrey L
Test Fit:
Randy B

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