Proportional brake controller automatically levels when mounted within a 90-degree vertical range and a 40-degree horizontal range. Includes digital display, 9 sensitivity settings, reverse-polarity protection, and continuous diagnostics. Call 800-298-8924 to order Curt brake controller part number C51140 or order online at Free expert support on all Curt products. Guaranteed Lowest Price and Fastest Shipping for Curt TriFlex Trailer Brake Controller - 1 to 4 Axles - Proportional. Brake Controller reviews from real customers.
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Price: $56.31

Curt TriFlex Trailer Brake Controller - 1 to 4 Axles - Proportional

Item # C51140

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Our Price: $56.31

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In Use/Installed

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  • Proportional Controller
  • Curt
  • Electric
  • Electric over Hydraulic
  • 2 - 8 Brakes
  • Automatic Leveling
  • 90 Degrees
  • Vehicle Mount
  • Digital Display

Curt Brake Controller - C51140

Proportional brake controller automatically levels when mounted within a 90-degree vertical range and a 40-degree horizontal range. Includes digital display, 9 sensitivity settings, reverse-polarity protection, and continuous diagnostics.


  • Brake controller activates trailer brakes in proportion to your vehicle's braking action
    • Automatically adjusts trailer's braking based on deceleration of tow vehicle
    • Activates immediately - no pausing like with time-delayed brake controllers
  • Automatic-leveling ability - internal sensor detects deceleration even if controller is not mounted flat
    • Position within 90 degrees up or down and within ±20 degrees side to side
  • 9 Sensitivity settings (boost settings) let you adjust initial braking power and aggressiveness
  • Triple-axis accelerometer is highly responsive, ensuring smooth, uniform stopping action
  • Continuous diagnostic check alerts you to any potential problems
  • Integrated safeguards protect your vehicle, the trailer, and the controller
    • Minimizes drain on car battery by entering power conservation mode after 30 minutes of inactivity
    • Keeps trailer brakes from overheating by reducing power output to them during prolonged stops
    • Defends brake controller and trailer breakaway systems against shorts
    • Prevents positive and negative power reversal with built-in polarity protection
  • Surface-mount technology (SMT) allows for consistent, reliable performance
    • Maximizes power output while producing minimal heat
    • Ensures superior operation in rough road conditions
  • Digital display communicates power and sensitivity settings and error codes
  • Built-in, slide-bar manual override
  • 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 or electric-over-hydraulic trailer brakes
  • Dimensions: 3-1/4" wide x 4" long x 7/8" tall
  • Mounting:
    • 90-Degree vertical plane operating range
    • 40-Degree horizontal plane operating range
  • Limited lifetime warranty

Note: If your vehicle's 7-Way trailer connector has LED test lights built into it, the TriFlex brake controller will not be compatible.

Proportional Braking

With a proportional brake controller, you can get heavy-duty emergency braking, general braking, or slow-to-an-idle braking for your trailer automatically. The intensity with which your trailer brakes are activated and the rate at which they are applied are dependent on the deceleration of your tow vehicle. This means that, unlike time-delay controllers - which send the same amount of preset power to your trailer brakes every time - proportional controllers are able to adapt to every braking situation differently. So, if you slam on the brakes in your truck, your trailer brakes will activate with that same extreme intensity. And if you merely slow down as you approach a red light, your trailer will gradually brake in the same manner. Just set the initial power level, select a sensitivity setting, and you're good to go.

As long as the TriFlex controller is properly mounted as indicated in the instructions, it will sense - via an internal inertia sensor - how your tow vehicle brakes. This triple-axis, inertia-based sensor responds to the deceleration of your tow vehicle as you brake by signaling the controller to send out enough power to your trailer brakes so that they are activated with an intensity that matches. The result is uniform braking across your towing setup. No push-pull action - just smooth, proportional braking every time.

Built-In Controls for Adjustable Power

Curt TriFlex Controls and Components

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

  1. Digital display
  2. Thumbwheel power output control
  3. Sensitivity adjustment switch
  4. Slide-bar manual override

Output Control

During the initial setup process, use the thumbwheel on top of the TriFlex 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.

Sensitivity Settings

Once you have the overall power set, you can fine-tune the power output by adjusting the sensitivity of the internal sensor. Use the switch on the side of the TriFlex to achieve your desired degree of intensity.

Move the switch toward you to boost the power output, causing your trailer brakes to activate with more intensity right off the bat. This means that they will also reach maximum braking faster simply because they will start out at that higher intensity. This is particularly beneficial if you are towing a heavy load because the intensity required to stop that load may be far greater than that needed to halt your vehicle. Therefore, sending out more initial power to the trailer brakes - and causing them to reach maximum braking faster - allows you to better control the trailer so that it doesn't push your tow vehicle before coming to a complete stop.

There are 9 sensitivity levels (boost levels), with 1 being the least sensitive. At level 9, the sensitivity of the internal sensor is as high as it can go. When you change the setting, the display on the TriFlex will flash the level before reverting back to showing the power output.

Safety Features

The TriFlex offers advanced safety features to prevent damage to various components of your towing setup. When the TriFlex is not in use, it will be in power-saving mode, reducing the power draw to minimize drain on your vehicle's battery. This power-conservation mode begins after 30 minutes of inactivity and ends the moment your vehicle's brake pedal is pressed.

When you stop at red lights, or any time that your truck and trailer are at a standstill with the brakes applied for a prolonged period of time, the TriFlex will reduce the power output to your trailer's brakes, preventing them from overheating.

If ever there is a time that you need to brake your trailer separately from your tow vehicle, the manual override lever is easily accessible. Pushing this slide engages the brakes on your trailer with either full power or the maximum power allowed by the output level, depending on which setting you select. In addition, when you activate this override, the brake lights on your trailer will illuminate, properly warning those behind you of the braking action of your rig.

Automatic Leveling and Simple Installation

The self-leveling feature of the TriFlex ensures that the brake controller continues to function even as you drive up steep hills or through the mountains. Simply mount it in your cab at a vertical angle that is within 90 degrees, and the controller will level itself automatically. Make sure that the controller is also positioned so that the side-to-side angle is within ±20 degrees.

Installation is a snap. After mounting the TriFlex unit in your cab using the included bracket, hardwire one end of the included pigtail harness directly into your vehicle. The other end plugs into the brake controller. To transfer the TriFlex to another vehicle or to remove it for storage, just unplug the unit and remove the screws that hold it place in the bracket. Curt offers a spare mounting bracket (C51144 - sold separately) that can be used to affix the TriFlex in your other automobile.

Installation Accessories

For even 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'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.

Surface-Mount Technology

Curt's TriFlex brake controller is built using surface-mount technology (SMT). This method of construction involves soldering electronic components directly to the surface of a printed circuit board. SMT eliminates the need for leads, which are used in older through-hole technology. The result is a circuit board that is smaller yet provides more routing area and that offers superior performance, reliability, and durability.

Curt SMT Circuit Boards

Circuit boards constructed using SMT have been shown to perform better under rough conditions with excessive vibration than those made using the through-hole method. And where would vibration be more likely to occur than in towing applications? SMT circuit boards also produce less heat, leading to increased durability and longer life. In addition, lower levels of resistance ensure better performance, especially for parts that operate at higher frequencies.

Each Curt circuit board is made using high-quality components that are pieced together in the most technologically savvy fashion, leading to greater predictability and reliability in functioning.

51140 Curt Tri-Flex Proportional Trailer Brake Control

C51140 Installation InstructionsInstallation Details C51140 Installation instructions

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Customer Reviews

Curt TriFlex Trailer Brake Controller - 1 to 4 Axles - Proportional - C51140

Average Customer Rating:  4.8 out of 5 stars   (138 Customer Reviews)

Proportional brake controller automatically levels when mounted within a 90-degree vertical range and a 40-degree horizontal range. Includes digital display, 9 sensitivity settings, reverse-polarity protection, and continuous diagnostics.
- C51140

by: Bill Y.09/28/2015

I installed this unit, hooked up my travel trailer and had it all calibrated and ready to hit the road in less than an hour. Took a 300 mile trip a few days later and the unit was flawless. Forget the old time delayed units, this is the way to go. Also, get the pigtail that is designed for your particular vehicle, it makes installation a snap (plug in to your vehicles available plugin and into the back of this unit) couldn't be simpler. Very satisfied with the unit and with Great products, great service. 228079


Still satisfied, works great.

Bill Y - 09/27/2016

- C51140

by: Tammy H.01/01/2017

I connected the Curt Brake controller into my 2007 Toyota 4runner. It took 5 minutes to hook up using the curt wiring adapter for my vehicle. I pulled a 16' aluminum stock trailer with one horse in it. There were no problems with braking and the braking action was very smooth on the trailer. I also have a weight distribution on the trailer which helps with using the Toyota in an "emergency" tow. The horse had an easy 3 hour tow with smooth braking and no swaying. Thanks etrailer for all the tools that make farm life easier. 329228

- C51140

by: Mike R.09/22/2014

Small size is convenient - easy to mount in a Tacoma. When setting it up for a single-axle 2,200-pound tent trailer with a brand new Dexter axle, I was surprised to find I have to run at the maximum output and sensitivity settings, but it works fine. 152489


Make sure the brakes are properly adjusted. They should be exerting a slight drag on the drum when spinning by hand. If the brakes are not adjusted correctly, you may be exerting more wear on the magnet than is necessary.

-- Patrick B - 09/29/2014


I dont know what changed, but the controller is working as expected now - I am pleased with its performance and convenient size.

Mike R - 09/16/2015

- C51140

by: Jeff H.08/01/2013

Items arrived quickly. Hesitant to buy "Drawtite",as I was told 'Made in China". However, it says on label 'Made in USA'! Needed additional spacer for 'middle' bolt.? Fairly easy install. Curt brake controller should be easy as well. All in all, a 'square deal! 92715


Hitch is fine.Curt controller had a malfunction, factory support -superb! Sent a new unit in 2 days!

Jeff H - 01/30/2015

- C51140

by: Lee A07/23/2013

I received my Curt triflex brake control in less than a week from ordering on line. It was so easy to put in and set up. I couldn't believe it. Just plug and play. 91176


It didnt. It would not adequately slow down or stop my 34 fifth wheel. I pulled it out and installed a Prodigy. The Prodigy works just fine.

Lee A - 01/21/2015

- C51140

by: Tom and Anita09/19/2016

Yes I received my order and installed the brake controller. All seems to be fine, although I have yet to tow with it yet. Here are a couple photos of the installation in my 2010 Toyota Tundra. 296409

- C51140

by: Kevin L09/12/2013

So far , so good . Install took a whole 5 minutes and the overall size is easily dealt with in my Tacoma . Nice to have the led display - not too bright but easy to read and understand diagnostics and output levels . The compact size is a real bonus and it's controls are easy to understand , no complaints at all . Best is it's bracket system - screw holes to mount to the truck side are outside of the main bracket dimensions which allows a lot easier install - great intuitive design instead of trying to position , remove controller and mark holes . I was able to actually drill right past the controller in-place and install the screws , dead simple . Kudos to Curt for a great design/product . 99562

- C51140

by: Joe R04/24/2014

placed into my 2014 RAM 1500 put it in place only took about a half hour with the right harness. 127226


Just curious, how much weight have you towed with the controller and how well did it perform? What setting did you run?

-- comment by: John P - 09/26/2015


Hi John I have a ram 1500 V6 . My camper is 19 ft about 4300 LBSI have the sensitivity setting at L7 and the thumbwheel set around 20 to 25 .. If every thing reads ok from the codes .the setting are easy to test with a short drive .Adjust your settings to your liking. after setting for awhile like over the winter or pulling out from a seasonal site you may need to run little heaver on the break for a short time . It has plenty of power to stop you with just the trailer brakes .

-- comment by: Joe R - 10/13/2015

- C51140

by: Ryan R04/12/2015

Installation was easy. Product works well. The power and sensitivity adjustments are very useful. 184853


Everything is still working fine.Thanks for Asking

Ryan R - 04/21/2016

- C51140

by: Bill B06/09/2014

Good buy, very easy to hook up and worked well. 134871


Im still using the above items and have had no problems with them. Thanks.

Bill B - 06/09/2015

- C51140

by: Howard S.04/06/2017

I bought a 7 pin trailer wiring/brake connection for my Dodge pickup. I installed it myself, the instructions were absolutely clear and correct. It was an easy installation. In the year since, I've pulled my trailer (tandem axle, 16') many times. The brakes continue to work perfectly as well as the lights. The connectors are solid, all work just like new. I recommend Etrailer parts and their people 100%! 363500

- C51140

by: Lyn J.03/31/2017

One of the best internet companies that I have ordered from and I have ordered a lot over the years. Kim was excellent help with my order. I elected for free ship and my order was packed and shipped out on Sat. And received on Wed. Pricing was about half of what my local trailer retailer ask. Bottom line, order from these people and you will not be disappointed. The Curt controller was very easy to install and adjust and works perfectly. The ball mount is massive, no worries about breaking this monster ! Very pleased with every aspect of this purchase. 362878

- C51140

by: Joe B.11/21/2015

Easy to install and set up. I can't believe the difference between this proportional controller and the simpler time delay type. Between the power output adjustment and the sensitivity adjustment, you can quickly and easily adjust the controller for your trailer. It took me about 5 minutes to dial it in perfectly! No more jerky trailer brakes! Thank you E-Trailer! 232383

- C51140

by: Mainly Dave07/22/2015

Installed and use on a 2014 FJ Cruiser. Need the wiring kit for the FJ. Installation was straight forward and everything needed was included. Took me about 2 hours but no problems. Using the unit is easy to understand. My only concern is that it does not seem to be able to lock up the brakes [even with the manual function.] But this might be due to my brakes being worn and not used recently. Have towed a fairly heavy load once [~3500 lbs,] and I am pleased with the braking function. I recommend the product. 213490

- C51140

by: Mark from Pa10/13/2013

Was very easy to install. Shipped out same day. I'm very particular so install took longer than necessary about 20 minutes. I don't like having extra holes or things mounted crooked on my truck. Used it same day I installed it to haul our livestock trailer. Worked great braking was very smooth. Can't say it is better or worse than any other controller but I am happy with this one. 103662


mark question for you is breaking between having the trailer load with livestock to empty is there lots of adjustment or no problems

-- comment by: mike - 04/10/2015

- C51140

by: Wayne08/19/2016

Quick and easy to install with the included C51451 wire harness. Start to finish was less than 5 minutes. Setup and adjustment was also quick and painless. What really made the 5 star rating was their lowest price promise. After my purchase I found it for a lower price elsewhere. A quick message to etrailer was all it took, with the details of where I found it and the price, and my card was refunded the difference plus a little more! This was my first purchase from etrailer and it will not be my last. 285587

- C51140

by: Greg C.08/04/2015

After talking at length (at least 15 minutes) to the rep on the phone, I choose the Curt TriFlex controller for my 2015 Silverado. It happens to be the same unit sold on Chevy's website (but cheaper on etrailor). The sales person was awesome! She wanted to be sure I got the right one, not trying to upsell me on something I didn't need. Just as she promised, it plugged right in under the dash and I even used an existing screw to mount the bracket. A 15minute install!!! I will shop here again. 216669

- C51140

by: Robert A.04/21/2017

The unit with the matching installation cable was easy to install once I found the factory installed plug-in port on my 07' Dodge Quad Cab. The videos didn't have my truck model and I had to go to the Curt mfg website to find a picture of the the location of the port. I have not hooked up the truck with the trailer yet to test and adjust the brakes but the controller installation and functionality test was very easy to accomplish and went smoothly with the instructions provided. 370441

- C51140

by: Rae W03/05/2017

I reviewed the connecting cord thinking I reviewed the whole thing but apparently not. This controller was great right out of the box. A you-tube quick review and installed myself in 1/2 hour. It worked fabulous as used it over the weekend. It seemed to set itself up for the best brake response and it sure worked smoothly. I am towing a 21 ft trailer with dual axles weighing about 45oo lbs and towed by a Buick Enclave 348888

- C51140

by: Doug S09/15/2013

To be honest, haven't installed yet. Have to run wiring in 2 trucks as neither has factory wiring. I want mounting to be not noticeable if I sell either vehicle. Based on reviews, and having my hands on it and the printed directions I believe it will fit my greatly fit my needs. I have a one month plus to get one vehicle ready for a road trip. LOL, I like to plan ahead. Will write more when I get working. 99999

- C51140

by: Eric J05/25/2017

Customer service was excellent! I needed an order rushed, and they couldn't ship to the PO box I provided. They immediately reached out and got delivery information so that my order could be shipped the same day. Very helpful, and very responsive! All the etrailer installation videos and diagrams they provide make the process even better! Would definitely recommend ordering from them. 384717

- C51140

by: frank in florida01/01/2014

Shipping was fast and product was exactly as described. It took longer to pull the factory plug from under the dash in my 2004 f250 than to complete the brake controller connections. My truck came factoy with the 7way plug and wiring installed. Adjustments were a breeze and the controller worked perfectly. 10 minutes or less install. I would recommend this to anyone. 111686

- C51140

by: Sharon K06/14/2016

Bought this controller for my husband, received it on a Wednesday my husband installed that night. The very next day we left to go up state camping. Going over the mountains my husband kept saying how impressed he was with the break controller. Easy to install. He installed it in a 2006 Dodge Ram 1500, he pulls a 2016, 32 foot camper. I would recommend this product!!! 261392

- C51140

by: Matt B.07/23/2015

Easy install. The product works as advertised. Installed on a 2013 Nissan Armada in order to tow our 27' travel trailer, dual axle; I had to mount the controller in a small slot below the stereo due to the fact that it would have been unsafe to install below the steering wheel. The item was small enough to fit perfectly. 213805

- C51140

by: Tom H03/10/2017

The C51140 controller I purchased for my 2016 Colorado was delivered on time, and was very easy to install. Took about 1/2 hour to install, make the initial set points and dial it in so my 18' RV stops nice and smooth. I couldn't ask for anything easier. I recommend this for anyone looking to buy a brake controller. 350930

- C51140

by: Jim H08/28/2015

Brake installed using the pig tail connector in 10 minutes. Initial test and it works very well. Very fast delivery and customer support was very helpful in picking out the right product for my needs. Also, I watched the video on how to install and it was spot on. Made install very quick and easy. 222302

- C51140

by: T09/24/2015

Works perfect. Very satisfied. My only small complaint was that I read many reviews from other customers of etrailer praising the speediness of their shipping; my order showed to be "in-stock" but took nearly a week before it actually shipped. Now once it left the facility the shipping was very fast. 227310

- C51140

by: T09/24/2015

Works perfect. Very satisfied. My only small complaint was that I read many reviews from other customers of etrailer praising the speediness of their shipping; my order showed to be "in-stock" but took nearly a week before it actually shipped. Now once it left the facility the shipping was very fast. 227309

- C51140

by: Gary S.05/05/2017

This trailer brake controller was a snap to install. Thanks to some videos that I watch. One video showed the exact location of the wires I needed to connect to, plus the colors of the wires. Have'nt hook to the trailer yet, but don't plan on any problems. Thank you very much! 376586

- C51140

by: Terry06/18/2014

The Curt proportional controller is versatile and effective. The wide vertical mounting orientation and self-leveling feature enables ease of installation in a variety of locations. The self-calibrating function adds to the efficiency of the controller's installation. 136217

- C51140

by: Mandy04/26/2017

Easy install with factory 7way plug didn't need anything extra not included in kit. 02 Chevrolet 2500HD pulling an aluminum 3 horse gooseneck trailer, this brake system works great so far loaded and unloaded. Mounted nicely out of way to the dash under shifter. 372907

- C51140

by: Jason04/18/2015

Installed like a charm on a 2005 Dodge Ram 1500 with factory 4-wire trailer connector. Ordered the universal wiring adapter. Excellent installation instructions and videos on eTrailer made installation easy. Have yet to pull a trailer with the controller. 186154

- C51140

by: Bryan H07/15/2016

Worked great. Relatively straightforward to install. The instructions were clear and I very much appreciated the installation videos on the e-trailer website. Wouldn't buy trailer wiring supplies or brake controllers anywhere else! 272278

- C51140

by: Virgil R.10/31/2014

Arrived in excellent condition. In the process of installing. Will add more when installation is complete if I can. Don't really expect any problems, as have purchased other products from etrailer and always very satisfied. 158646

- C51140

by: George08/15/2015

This is my second curt brake controller I have ordered thru etrailer. Now both trucks have curts on them. Simple and dependable. Shipping is always very fast and all my towing parts and needs will be ordered thru etrailer. 219476

- C51140

by: Matt R.10/06/2013

Installed on my '05 Silverado. We pulled the rv this weekend with no problems. The controller worked as it should. My only issue was that the screws that mount the controller to the bracket were missing from the package. 102745

- C51140

by: Raj04/24/2017

Product works as described. Giving it 3 because the brake intensity selector is loose and will adjust itself +/- 0.2 while im driving. Its not a big enough problem that it makes driving hazardous but its an annoyance. 371746

- C51140

by: Bert11/13/2013

Have installed but not used yet. I like the slim line on this product, it take less room under the dash on my van install, less chance of a knee bump and if I do hit the knee the rounded corners should reduce injury 107182

- C51140

by: John J12/09/2013

Product seems to be what I expected. I will not install the controller until we get some warmer weather up here in Michigan. Till then, thank you for the quick delivery. Ordered it Tuesday, got it Saturday. 109667

- C51140

by: Gene Norris12/15/2016

Part works great, Thanks for keeping me up on sales that comes out. Great products I will keep ordering from you, when I need it. Again Thanks...................Gene ...................Roll Tide>>>>>>>>>>>> 325390

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by: John06/08/2017

Received the brake controller and with the harness for my 08 Nissan Armada quickly. Installed in 10 minutes. Simple enough. Most of the time was just spent figuring out how and where I wanted to mount it. 390666

- C51140

by: Dan P08/26/2013

Received purchase fast an was packaged safely. Installation was easy & plugged right up. Have hauled a full three horse trailer and with minor adjustments had smooth solid stops. Thanks, Dan 96881

- C51140

by: Mark D.04/13/2017

Researched, purchased and installed a hitch and brake controller for my 2009 F-150. It was so much easier using etrailer. I have recommended them to several friends for their towing needs. 366834

- C51140

by: Michael02/07/2017

Can always count on the folks at E Trailer. Products are quality, no flim flam operation her. Always more than willing to get proper fit or to correct mistakes. Who hasn't made a mistake? 341594

- C51140

by: Mike B.08/29/2014

Works well so far. It was a very easy install on my 2007 Chevy Tahoe. The videos were really great. The controller arrived promptly. I appreciate the great service! 149234

- C51140

by: Rick & Lynn05/23/2014

Great service and product! It took 25 minutes to install and the calibration was a snap! I would very much recommend Etrailer to anyone. Thanks for making this a great experience. 132035

- C51140

by: Carl02/04/2014

You guys are asome order my brake controller late Friday nite and an hour later it was shipped Received it on Monday What I ordered works great already installed on truck. Thankyou 115748

- C51140

by: Jonathan S04/24/2015

Product arrived as scheduled and liked the tracking access. Have not had the opportunity to install the product but will be following the direction with help from the videos 187863

- C51140

by: Justin6.0L08/28/2013

Product arrived in a timely manner, seemed well packaged and took less then 5 minutes to install. will be towing 23ft camper next month and looking forward to using this. 97285

- C51140

by: David C.06/15/2017

Controller didn't work. Spent lots of money with Nissan on replacement parts and technician trying to figure out what was wrong. Controller defective after bench testing. 394404

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

  • Display Code Meanings for Curt TriFlex Brake Controller
  • The Curt Triflex part # C51140 that you referenced should show a single decimal point when there is not trailer connected and two decimal points when a trailer is connected. I attached a couple pictures that show what the display letters/codes mean on your brake controller. Since none of them are two dash lines feel free to check out the picture I attached and see what it might be, or email me back with a picture of the display so I can show it to Curt if your display is different. Have...
    view full answer...

  • Installing a Brake Controller on a 2013 Chrysler Town and Country
  • There will have to bee some cutting and splicing to install a brake controller on your 2013 Chrysler Town and Country. Chrysler did not add a factory brake controller harness to the Town and Country, so the brake controller will need to be hardwired. The good news is that you will likely only have to splice one wire into your vehicle wiring. To install a brake controller like the Curt TriFlex, # C51140, that you referenced, you will want the Curt Universal Brake Controller Wiring Adapter,...
    view full answer...

  • Troubleshooting Curt TriFlex Brake Controller Showing Overload Error
  • This The OL error you're seeing means that there is a short somewhere in the brake output circuit, which is the blue wire that exits the rear of the controller. The usual cause of this is a corroded or damaged trailer connector, but because this is a recent installation on an almost new vehicle, that's probably not the case. In the install, you ran the gray two-wire cable from the rear of the vehicle. The white wire in the cable should be connected to the blue wire on the 7-way connector...
    view full answer...

  • What Is Needed To Install Brake Controller On 2005 Ford F-150 With Factory Tow Package
  • On your 2005 Ford F-150 with the towing package, there will be a port under the dash that the Curt Custom Wiring Adapter, part # C51322 plugs into. I have attached a photo that has a red arrow pointing to the location on your truck. The Curt Venturer Trailer Brake Controller, part # C51110 is a time-delayed brake controller designed for a trailer with electric brakes only. It uses a preset sensitivity setting to activate your trailer brakes when you press the brake pedal in your truck....
    view full answer...

  • Resetting Curt TriFlex Trailer Brake Controller With Unknown Display
  • I called my contact at Curt about the Curt TriFlex Trailer Brake Controller, part # C51140. They told me that you should disconnect the power to the unit and leave it disconnected for 15 or so seconds and then plug it back it. It should recalibrate itself and work fine after that.
    view full answer...

  • Curt TriFlex Brake Controller # C51140 Does Not Show Red Dot on Display After Installation
  • The Curt TriFlex Trailer Brake Controller, part # C51140, and the matching harness for your 2007 Chevrolet Silverado Classic, part # C51352, will work with your vehicle as long as your 7-way connector on your rear bumper is not the type that includes LED test lights. Such 7-way connectors are not compatible with the Curt TriFlex. It is critical that before installing the controller the negative battery terminal be disconnected to avoid potential damage to the unit. Also, the trailer...
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  • Does the Curt TriFlex Brake Controller Need to be Disconnected when Backing Up
  • You should not have to disconnect the Curt TriFlex Brake Controller, # C51140, when backing up. Brake controllers are designed to send power to the trailer brakes when you step on the brake pedal. When backing up, you typically step on the brake pedal several times, so many people simply disconnect the trailer connector from the tow vehicle before backing up. The Curt TriFlex brake controller is a proportional brake controller that uses an internal inertia sensor to sense the braking...
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  • Trailer Brakes On Camper are Humming
  • What you are hearing is the brake magnet being activated. If this is happening immediately upon plugging in the trailer, while the brakes on the truck are NOT being applied, it would indicate that something is wired incorrectly. Does the truck have a 6-way or 6 pin trailer connector? If so, either the connector on the vehicle or the trailer would need to be rewired. There are two accepted methods of wiring a 6-way connector. One method uses the center pin to carry the brake controller...
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  • Troubleshooting Brake Controller That Gets Hot and Trailer Brakes that Lock Up
  • It does sound like there is a short on your trailer. If the brakes locked up and the brake controller unit got very warm it sounds like there is a short on the trailer's 12V power circuit that is causing the electric brakes to lock up. It is possible for different circuits to become bridged together and your 12V power feed might be getting to the brakes. First, check the trailer plug inside and out for signs of corrosion. Even slight greenish or whitish discoloration can indicate corrosion....
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  • Brake Controller and Trailer Wiring Installation on 1997 Jeep Grand Cherokee
  • To install a brake contorller on your 1997 Grand Cherokee, you'd first need to install a 4-pole connector, using the Tow Ready # 118349. How you'd proceed next will depend on the connector use on the trailer you'll want to pull. I'd recommend using a 7-way because it's the most common. You can always use an adapter like part # HM47570 to convert it to anything else you'd need. To actuate the electric brakes on the trailer, you'd need a brake controller. I'd recommend going with a...
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  • Curt TriFlex Trailer Brake Controller Does Not Power On
  • First, lets just make sure you are using the correct wiring harness. For a 2012 Nissan Pathfinder it is # C51382. What you will want to do is check the black wire. There should be power on the black wire leading to the controller. If there is no power leading to the controller then you will need to check the owners manual for all of the fuse/relays locations related to the tow package wiring and brake controller wiring. Chances are that it is just missing a fuse or relay. If you are...
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  • LED Display of Curt TriFlex # C51140 Brake Controller Remains Illuminated When Vehicle is Shut Off
  • Because it's connected to a constant 12-volt power source, the LED you mention will remain illuminated after the vehicle is shut off. This is normal, and does not indicate a problem of any kind. After 15 or so minutes of inactivity, the brake controller goes into a 'sleep' mode, and will reactivate next time the brake pedal is pressed. The LED only draws a few milliamps of power, which would only drain the battery if the vehicle sat unused for months. You could certainly unplug the controller...
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  • Difference Between the Curt Triflex and Reflex Brake Controllers
  • The biggest difference between the Curt Triflex part # C51140 and the Curt Reflex Brake Controller part # C51130 is that the Triflex uses a triple-axis accelerometer and the Reflex uses a double-axis accelerometer. The triple-axis will ensure that you get smooth consistent braking in all braking situations. Because of that I would recommend the Triflex.
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  • Brake Controller Recommendation for a 2012 Tiffin Allegro
  • There isn't a plug-in adapter that would allow for a simple installation of a brake controller like the Curt Triflex Brake Controller part # C51140 in your 2012 Tiffin Allegro, but from the research I did there should be a bundle of wires under your dash that a brake controller would install to. For a Tekonsha brake controller the brake controller we recommend the most is the Prodigy P2 Brake Controller part # 90885. This is the best selling controller on the market because of how easy...
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  • Troubleshooting Curt Tri Flex Brake Controller that Locks up Trailer Brakes
  • L.1 is the lowest sensitivity that the Curt Tri-Flex part # C51140 can be adjusted down to. However, you can also adjust the overall brake output power with the output control. The output control thumbwheel can be adjusted from the lowest setting all the way up to the highest of 9.9. If you have the controller adjusted all the way down on both of the mentioned settings and it is still locking up then I would assume you have the brake light circuit shorting out to the brake output circuit...
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  • Curt TriFlex Brake Controller Shows d.C. and Other Error Messages on 2005 Toyota Tundra
  • The first thing you will want to try is to unplug your TriFlex brake controller # C51140 for about 15 seconds or more. Then, before plugging it back in go back through the instructions as if you were installing the controller for the first time. Once all electrical connections are complete and the single decimal point is seen, while parked on a level surface, plug the trailers electrical connector into the tow vehicle’s plug. Making the trailer connection initiates the mounting position...
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  • What Problems Does the Curt Triflex Brake Controller Have with 7-Ways With LED Test Lights
  • What happens is that the load that LED puts on the brake output circuit tricks the brake controller into thinking that there is a trailer connected and the brake controller will start activating regardless if there is a trailer connected or not. Technically it would work just fine with a trailer, its just that it will always activate regardless if there is a trailer back there or not. I attached installation instructions and an install video for you to check out also.
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  • Troubleshooting Error Code A.E. on Curt TriFlex Trailer Brake Controller C51140
  • The operating instructions for the Curt Triflex brake controller # C51140, which are linked for you, indicate on page 19 that if the unit displays the error code A.E. this indicates an internal fault with the controller's accelerometer. This is not a serviceable problem and the unit should be replaced or referred to Curt for warranty service under the terms of the limited lifetime warranty. You may care to review the linked article on brake controllers.
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  • Brake Controller Install Harness and Brake Controller Recommendation for 2015 Chevy Silverado 1500
  • Yes, the Curt brake controller install harness part # C51451 that you referenced will allow you to install a Curt brake controller in your 2015 Chevy Silverado 1500 like the Curt TriFlex part # C51140.
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  • Troubleshooting Curt Fri-Flex Brake Controller Installation in 2014 Nissan Frontier
  • I suggest you disconnect your trailer and test both the tow vehicle and trailer independently. Please note that if your vehicle's 7-way trailer connector has LED test lights built into it, then the TriFlex brake controller will not be compatible. First you can check the signals going into and leaving the Tri-Flex. Apply a circuit tester like # 40376 to the black wire at the controller. This wire carries 12V power to the Tri-Flex and should be hot at all times, even when the vehicle is...
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  • Does Curt TriFlex Brake Controller Have to be Reset and Calibrated Every Time Vehicle Is Turned Off
  • No, modern brake controllers such as the Curt TriFlex # C51140 will not have to set up and recalibrated every time the vehicle is turned off. It will keep the settings you use. The connection to the battery is not shut off when the motor is turned off. The controller will still draw power but very, very little so as not to run down the battery.
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  • Curt TriFlex Trailer Brake Controller Shows dc with Trailer Connected to 2012 Toyota Tundra
  • The dc does indeed mean that the controller is not sensing the trailer on the Curt TriFlex brake controller # C51140. This could be happening if the gain is set too low on the controller. Trying adjusting the power output and make sure the controller is mounted within the range specified in the instructions because not being level or straight can affect it. The Tundra also has an issue with an inadequate ground for a brake controller at the factory connection point for wiring harness...
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  • Curt Triflex Trailer Brake Controller Shows Power All the Time on Blue Wire
  • You should only be seeing 12 volts on the blue wire on the brake controller, # C51140, when the manual override is used. If there is constant power all the time then there is either something that is miswired or a problem inside the controller and it will need to be replaced. Brake controllers do send back a minimum amount of voltage to check for a connected trailer but it should not be enough to activate the brakes. In the truck cab you will need to sever the blue wire several inches...
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  • Troubleshooting Curt TriFlex Trailer Brake Controller With Erratic Digital Displays
  • I called my contact at Curt and they told me you can possibly reset the brake controller by unplugging the 12V power form it and then let it sit for a few minutes. Then turn it back on and that may take care of the issue. Make sure the trailer is not plugged in when you do this. Then I recommend checking the trailer plug with the trailer unhooked to see if there is current when the brake controller is off and then check it again when the controller is on. They said the erratic display...
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  • Brake Controller Wiring Harness for 2015 GMC Sierra 1500 and Curt TriFlex Brake Controller
  • For your 2015 GMC Sierra 1500 and Curt TriFlex brake controller # C51140 you will need wiring harness # C51451 to plug the controller into your truck. I have linked videos and instructions for both parts for you.
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  • Trailer Hitch, Wiring, Brake Controller and Accessories for a 2011 Nissan Xterra
  • For your 2011 Nissan Xterra Curt hitch # 13514 and wiring harness # 118266 will work just fine. Brake controller and harness # C51140 and # C51515 are also going to work just fine. But instead of using # ETBC7 you would use # 5506. this is because you do not need all of the stuff included with the ETBC7. You will still need to route the brake controller blue output wire to the back of the 7-Way, attach it to the back of the 7-Way in the 7 o'clock position. Remove the wire that is already...
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  • Can Curt TriFlex Trailer Brake Controller # C51140 Be Temporarily Disabled When Backing Up
  • I did some research on this controller for your 2006 Chevrolet Silverado, and there are no features available that will turn the Curt TriFlex Brake Controller, part # C51140 off. The best way to temporarily disable the controller when you intend to back up is to unplug the trailer. If you were to unplug the controller, it would have to be reset when it is plugged back in. I spoke with my contact at Curt and they strongly advised against doing this because if someone failed to reconnect...
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  • Location of Brake Controller Connector in 2014 Ford Expedition
  • The connector for the brake controller is located behind the dash just to the left of the glove box. The easiest way to access the plug is to 'drop' the glove box. You'll need to either remove a few screws on the interior of the glove box, or push in on the sides to release it so it'll swing down. Once the glove box is dropped, you'll see the plug next to the glove box on the left.
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  • Installation Of Brake Controller On 2015 Toyota Tundra
  • If you have the towing package and the factory 7-way at the back of your 2015 Tundra, the correct plug-in harness for your vehicle is the Curt TriFlex, part # C51140 is part # C51455. I have attached a photo of the location under your dash where the plug-in adapter will be connected to. I have attached an installation video for a brake controller on a Tundra that should be very similar to yours. If you do not have the factory brake control wiring harness port you will need to hard wire...
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Info for this part was:

Test Fit:
Joe V

Edited by:
Leah B

Photos by:
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Expert Research:
Michael L

Video by:
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Written by:
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Installed by:
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Video Edited:
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Test Fit:
Nicholas E

Test Fit:
Rick A

Expert Research:
John H

Updated by:
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Video Edited:
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Video Edited:
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