Curt TriFlex Trailer Brake Controller - 1 to 4 Axles - Proportional
Curt Custom Wiring Adapter for Trailer Brake Controllers - Dual Plug In

Part Numbers: C51140,C51436


Our Price: $111.43

You Save: $33.06

This item qualifies for Free Shipping

zoom in icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.
Please enter a valid email address.

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

Error submitting comment. Please try again momentarily.

pop out icon replay 360 icon
horizontal rotate icon

Product Images

In Use/Installed

Customer Photos

Curt TriFlex Trailer Brake Controller - 1 to 4 Axles - Proportional
part number: 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

California residents: click here

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

California residents: click here

Customer Reviews

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

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

Average Customer Rating:  4.7 out of 5 stars   (310 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. 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.

- C51140
by: Jon02/11/2019

Installed in my truck only took about a hour plugs in to the original 604157

- 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: Rick10/10/2018

Works very well ! 573332

- 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


Still using the products no problems, everything’s works great.

Howard S - 04/06/2018


- C51140
by: Bill02/26/2019

seemed to work great towing our 16' iPod travel trailer! 608503

- 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: Jason S07/30/2017

I recently bought a Kurt trailer brake controller with adaptor. I have to say, that it was the easiest thing to hook up. The product was also shipped to my home very fast. I did not think I was going to receive the package until the next week, but it came just in time to use it the following day for my work. i Love ordering products from etrailer, I have only had really great service and good products from them. I will for sure, order from them again. 414526

- C51140
by: William g09/22/2018

Fortunately my F150 had the trailer package so the pigtail plugged right in. Only snag was I had to fabricate a piece to attach to the instrument panel (lower right) to get the correct angle they specify. That took some work. But it all came together nicely. See attached picture. The brake control works great. Good price. 567828

- 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: Dave10/14/2018

I am very excited to try it, however the quick connect, doesn't seem to fit my 2004 3/4 ton Chevy Express van. Th brake control harness #51451. It's for the Trifles brake controller. If it is the correct harness I cannot find where to plot in . The vehicle end of the harness will not fit available spots on fuse block . Any help would be appreciated. Thanks Dave 574308


The 2004 Chevrolet Express Van does not have a plug and play adapter available for the brake controller at this time. The C51451 will not have a place to plug in in your vehicle. The adapter you will need with the curt triflex is part # C51515
Universal Wiring Adapter for Curt Trailer Brake Controllers
. The part C51515 pig tail plugs into the wiring that is coming out of the back of triflex. There is some wiring that needs to be done with this brake controller installation. If your 2004 Chevrolet express van has a towing package from the factory the blue brake wire is already ran from the back of the vehicle to the front. It is located under the dash near the emergency brake pedal. The blue wire from the brake controller wiring pigtail will butt connect to the blue wire that was ran from the factory. You will also need kit part # 5506
Wiring Kit for 2, 4, 6, and 8 Brake Electric Trailer Brake Controllers
. Using the duplex wire from the kit you want to butt connect the black wire to the black wire coming from the brake controller. Using a ring terminal connect the black wire to the 30 amp circuit breaker included in the kit that you will install under the hood. Then using an extra cut piece of black wire connect from the circuit breaker to the positive side of the battery. The white ground wire will then connect to the negative side of the battery. The red wire from the brake controller butt connects to the brake switch wire and will need to be located in the van. In a Chevrolet express van the brake switch wire is normally light blue and located in the Body Control Module of the van. The BCM is normally located behind the passenger side dash. The brake switch wire on the van is typically the light blue wire but you want to use a circuit tester to test for function. You are looking for the wire that only shows power when the brake pedal is pressed. Once you have located that brake switch wire, connect the red wire from the brake controller to that. If your chevrolet express van has a towing package it should have a round plug with a cap inside the drivers side frame rail at the back of the van. You can now use a part # 30955
Replacement Custom Multi-Tow 7-Way and 4-Way Trailer Connectors
to give the van a 7 way connector. If your van does not have a towing package the blue wire will not be ran for you. You will need part # ETBC7
Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires
and not the part # 5506
Wiring Kit for 2, 4, 6, and 8 Brake Electric Trailer Brake Controllers
. The ETBC7 includes the 7 way connector, circuit breakers and duplex wire. The 7 way connector will need to be wired to the front of the vehicle before you can finish the installation I described above using the duplex wire in the kit. You also need a 4-way connector to plug into the 7 way connector part # 118392
T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
for the 2004 Chevrolet express van. I have attached FAQs on wiring in a 7-way connector.

-- Heather A - 10/16/2018


- 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: 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: Alan11/17/2017

2003 Ranger XLT Installation was fun! I tend to ignore instructions especially when those instructions mount the device where my knee is constantly banging into that device. See the photo. Would loved to have a longer extension cable to reach into engine compartment. If you are not mechanically and electrically gifted, have somebody that is do the installation. Had the device not initialize once at the beginning of a trip. After thirty minutes of trouble tracing, decided nothing was wrong, unplugged the cable for a few minutes then reconnected and initialization completed correctly and I had brakes. Now I unplug the device whenever I'm not towing. 452856

- C51140
by: Chris H07/31/2017

I purchased this controller along with the direct fit wiring harness and 7 way trailer harness for my 2000 F250SD. Install was easy. I would highly suggest buying the direct fit harness with this controller (I was replacing a spliced in system that was having intermittent issues). The only trailer I tow with brakes is an 18' landscape/utility trailer that may be loaded with 1000# one week and 7000# the next, so the inertia driven system should make for a much smoother ride. Service was great, really appreciated the follow up email to make sure the product arrived in good order and all my needs had been met. Etrailer will be my first stop for trailer related needs in the future. 412923

- C51140
by: Vincenzo09/05/2018

Wow! All works to perfection ! From the Website wade of specification of what I needed for my set up to fast delivery and plug n play install ! This is my second order from etrailer & will be for all my needs! I installed it to my right knee side , so not to hit it in & out daily, but any place will work - tie up extra wire securely. Safe journey !! 561685

- C51140
by: Jason J.06/24/2019

Easy to set up and operate. The controls are less than intuitive. There’s a sensitivity dial and a force level slider that seem to affect the application of the brakes. It’s not exactly clear which one is more important or has the most impact. The unit works well at highway speed but at low speed operations seems to apply the brakes aggressively to the trailer. This is my first experience with a brake controller so can’t compare with other units. It does make parking lot operations somewhat clumsy. It definitely gets the job done though. 662164

- 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: 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: 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: Dave R10/21/2019

Works great easy to mount 719199

- C51140
by: David10/02/2019

Great price installation very easy great idea on the bracket with the little ears ,so you mount tight to the console, all the plug in work like a factory installation great job 711988

- C51140
by: Brad09/27/2019

This is a great place to get anything to do with brake controllers and wiring for RVs or trailers if you need help purchasing and installing very knowledgeable 708412

- C51140
by: Kenneth09/25/2019

Super easy plug and play install on 2020 Jeep Gladiator 707611

- C51140
by: Justin C09/04/2019

The product worked great. It was easy to install and setup. I would definitely recommend it to others. 697497

- C51140
by: Mel08/21/2019

I got home early today from work and found my brake controller waiting for me.(The one thing I did not like seeing was that, although I have a drop box for all parcels next to the fence, it was placed on top of the box. LAZY DELIVERY PERSON! ) Anyway, I took it in and looked it over and decide to do the install. It took longer for me to get the cover off the box where the plug goes,then to do the entire install. Since I didn't want to drill any holes(yet) I used an existing screw down low. Now, I'm just waiting for my son to bring his dump trailer over,which he will leave with me for a few months. Stay tuned,more pictures and review still to come. 692045

- C51140
by: Richard08/17/2019

Easy installation. Works great 690482

- C51140
by: Robert08/16/2019

By far one of the best customer service experiences EVER!! We recommend etrailer hands down! 689950

- C51140
by: Carl08/15/2019

The unit looks very good. I'm putting it on my 2019 Silverado to pull a travel trailer. The truck is prewired and this unit just plugs in. I recommend this controller. 688793

- C51436
by: John08/08/2019

Great. Paula was outstanding. !!!!! 682253

- C51140
by: Nicholas08/07/2019

I chose this controller for it's 9 levels of sensitivity as other controllers I've had were too aggressive on even the lowest setting and only had 3 sensitivity levels. I have only pulled a couple loads using this controller; it was not too aggressive and performed well pulling a 30-ish year old trailer with tandem mobile home axles. The trailer was loaded to the max capacity of the axles, well maybe even a little over, and while I did have it on the most sensitive setting at max gain, I did not want any more braking capacity. Ordering it with the factory plug adapter made installation a breeze on my 96 Ford F250. 681994

- C51140
by: Jason J08/06/2019

Does the job. It’s not great at low speed maneuvering. It seems to apply the break pretty heavily when you’re moving around a parking lot or in a neighborhood. Otherwise I’m very happy with it’s function. 681346

- C51140
by: James07/29/2019

Easy to install and worked great right out of the box. 677791

- C51140
by: Pat V07/26/2019

The hardest part of the job was finding the pre-installed connector on the Tacoma. It is tucked in behind a wire bundle so you have to know where to look. Once found, simple plug and play. 678098

- C51140
by: James07/23/2019

Missing parts arrived, thanks Angela W! 674475

- C51140
by: Josh07/23/2019

Product made a constant clicking sound. E trailer wouldn’t allow it to be returned due to it having been installed. Wouldn’t have known about the clicking issue without installing it. Had to replace with a different controller. Poor quality control on this product and customer support wasn’t much better. 673934


According to Curt, the clicking heard is an internal switch actuating, and the noise is completely normal.

-- Mike L - 07/24/2019


- C51140
by: Bob07/21/2019

It was fast service and exactly what they said. 673425

- C51140
by: Ian07/05/2019

2011 Pathfinder Silver. I had previously swapped out the original flat 4 plug with the OEM 7-pin harness. Bought this controller + connector and installed it in < 5min. Could not have been easier to connect. I'll be able to test it in a few days once I get my pop-up from storage. 666871

- C51140
by: Charlied07/03/2019

Preforms as presented. Setup, pairing was a breeze. Highly recommend your consideration. 666157

- C51140
by: Dennis06/29/2019

Excellent service and great products 664341

- C51140
by: Robert06/26/2019

I received my order in just 2 days. you tube video and inclosed instructions were very clear. Instalition was very simple. Took 15 minutes. Very pleased. 663187

- C51140
by: Troy06/21/2019

Great product and easy to install with the pigtail adapter. 661109

- C51140
by: Gregg06/06/2019

I like the installation photos provided in the Q&A section. Fast shipping. 654104

- C51140
by: Daryn05/28/2019

Installed in my 2012 Chevy Tahoe in about 20 minutes. Put it to work 15 minutes later and everyting performed perfectly. Hauling an 8 x 16 tandem. Controls are a piece of cake, set-up is a breeze. 647630

- C51140
by: Good Product05/15/2019

This product is great and does a fine job...just make sure you mount it correctly. I wanted to mount it vertically instead of horizontally and it WON'T function correctly. I should have gone with a regular version instead of a fancy sensing version of brake bad! 642181


Like most all proportional brake controllers, the Curt Triflex needs to be mounted pointed in the direction of travel, level on a side to side plane as described in the instructions linked above. Older time-delayed controllers are indeed more forgiving about how theyre attached to the vehicle, but the braking performance gained from a proportional controller is far superior to that of time-delayed controllers.

-- Mike L - 05/16/2019


- C51140
by: John R.05/11/2019

Worked for a couple months and broke. Save yourself the hassle and just buy the Curt brake controllers that are made in the USA. They costs a little more up front, but the higher quality of the design and components is worth it. 640867

- C51140
by: Charles05/03/2019

This brake controller works well. On long trips adjusting is necessary and the Curt TriFlex makes it easy. Search for your application including adapter cable. ETrailer Customer Service is excellent. 637556

- C51140
by: Larissa05/03/2019

Bought this brake controller for my old 1985 F350. I was still using the old style brake controller hooked up to my brake fluid lines. Was able to easily pull the old controller and use the same holes under my dash to bolt the new electric one in, had to do some electrical splicing of course... I typically haul a 3 horse trailer w/living quarters, but also a 3 horse bumper pull and equipment trailers. Brake controller works great on my big and small trailers. Settings are easy to configure and I have no doubt my brake controller will work when hauling down the road. 637033

- C51140
by: Marc04/27/2019

Installed this brake controller last weekend. etrailer has helpful videos that also include associated products with part numbers. Watching the video and checking other references confirmed I needed the wiring harness, too. So I ordered both and it made the install go smoothly. 635466

- C51140
by: Michel04/22/2019

Installation was easy with Adapter cable and Controller which I installed on top of dash board cover and required only one hole to be drilled. Installation location allows for easy access to adjust settings, apply the trailer brakes alone and see the display. Tough part was locating the 2010 Ford F53, Wennibago, Vista, OEM connector which was out of sight. Remove the dash board cover, which was easy, then look for the big harness (see pictures) and the smaller cable which splits away from it. None of the literature explained that the connector is gray for six pins although only for pins are in the connector. Once found, just plug things together and it all works. 634129

- C51140
by: John B.04/15/2019

Easy to install, works perfectly, no pr oblems! 628871

Show More Reviews

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

  • Parts Needed to Install Curt TriFlex Brake Controller in GMC Van and Ford F-53
  • To install the Curt TriFlex # C51140 trailer brake controller in your 2006 GMC Savana Van you will need to wire in harness part # C51515. Vehicles with the 7-way tow package have the blue output brake wire already run from the back to the front. It is located under the dash near the emergency brake pedal. This connects to the blue wire on the harness. The white wire connects to battery negative, the red wire connects to the cold side of the brake light switch and the black wire connects
    view full answer...

  • Choosing Proportional or Time Delayed Brake Controller for Truck with Manual Transmission
  • The Curt TriFlex Trailer Brake Controller # C51140 and Universal Wiring Adapter # C51515 is an excellent choice for your 1986 Ford Ranger with a manual transmission. Proportional brake controllers like the Curt TriFlex have an internal inertia sensor which responds to the deceleration of your tow vehicle. Letting your foot off the gas pedal for a few seconds to shift gears does not create enough of a deceleration to send the signal to engage the brakes on the trailer. The controller
    view full answer...

  • Correct Wiring Harness for the Curt Triflex Brake Controller
  • The Curt Triflex brake controller # C51140 is an excellent choice when adding a brake controller to your vehicle. This brake controller activates trailer brakes in proportion to your vehicle's braking action, automatically adjusts trailer's braking based on deceleration of tow vehicle, and activates immediately with no pausing like with time-delayed brake controllers. But when trying to find the correct wiring harness to install it into a 2008 GMC Denali XL, the answer is the Universal
    view full answer...

  • Where Is Brake Controller Install Port on 2017 Ram 1500
  • To install a Curt brake controller like the part # C51140 in a 2017 Ram 1500 the correct install harness is the part # C51458. If you check out the install video I attached below you'll see exactly how a similar brake controller installs on a 2017 Ram 1500 like what you have. Fast forward to the 2:30 section of the video to see where the port is found.
    view full answer...

  • Could Curt Triflex Brake Controller Drain Truck Battery
  • Brake controllers like the Triflex part # C51140 will have an indicator light that will stay on for several minutes after the vehicle has stopped running. It eventually will go into sleep mode after a period of time. That indicator draws such a low amount that your battery would die from inactivity before it would drain it. It is most likely coincidence that you installed the controller recently. I'd take the truck to a local auto parts store to have the battery and charging system tested.
    view full answer...

  • Are the Curt TriFlex # C51140 and Curt Adapter # C51453 a Fit for a 2014 Ram 1500 4WD 5.7 Hemi
  • You have exactly what you need for installing a brake controller in your 2014 Ram 1500. Brake controllers, like your Curt TriFlex # C51140, aren't necessarily vehicle specific, but the plug-in wiring adapter harnesses are. The correct one for your 1500 is the Curt # C51453 that you referenced. This will plug into the port under your driver side dash and allow you to easily install and remove the controller when needed.
    view full answer...

  • Troubleshooting Curt Triflex Brake Controller that Locks Brakes Up On Lightest Setting
  • It sounds like your brake output circuit may be shorting out to the stoplight circuit of your trailer wiring and that is why the brakes want to lock up immediately. An easy way to test this is to check to see if the brakes end up pulsating when you have either blinker on. If so, then what I described is happening. Otherwise, did the brake controller's position change? Since it is a proportional controller it has to sit level horizontally and vertically to allow the controller to function
    view full answer...

  • Connection Shortage On Brake Controller Wiring
  • The issue is most likely on the trailer instead of a brake controller like # C51140 for example. I know you said you adjusted the brakes but I recommend adjusting the brakes more. Take a look at our video on how we adjust trailer brake assemblies, fast-forward to the 4:35 mark of the video. Have you tested the brake magnets already? I have an article attached that goes into detail on how to test the brake magnets if you have not done so already. The wire running inside the axle
    view full answer...

  • Installing the Curt TriFlex Trailer Brake Controller on a 2017 Chevrolet Colorado
  • I am having a hard time trying to understand your problem so bear with me here but it sounds like you are trying to install the Curt TriFlex Trailer Brake Controller part # C51140 on your 2017 Chevrolet Colorado with the Universal Wiring Adapter part # C51515. If that is the case then you are off to a great start as this is the correct harness for your Colorado. If your Colorado came with a factory 7-way then the wires you need to attach the harness to are already ran underneath the
    view full answer...

  • Troubleshooting Curt TriFlex Trailer Brake Controller Showing Red Dot and Number without Trailer
  • If the red dot on your Curt TriFlex Trailer Brake Controller # C51140 remains on without a trailer connected, this can be an indication that the red wire from the controller is connected to the wrong side of the stoplight switch on your vehicle. I recommend verifying that the red wire is connected to the cold side of the stop light switch, which is the wire that ONLY receives power with the brake pedal depressed, and no power with any other function. You can use a circuit tester like #
    view full answer...

  • Troubleshooting Curt Triflex Brake Controller that Shows Two Red Lines on Display
  • The Curt Triflex # C51140 is somewhat known for having internal bugs that make it act odd at times. The simple solution is to unplug the controller for a few seconds and then plug it back. This typically clears out the bugs and gets it working again. Try that and let me know if that fixes it.
    view full answer...

  • Brake Controller Install Harness for Installing Curt Triflex in a 2016 Ram 1500
  • To install the Curt Triflex brake controller part # C51140 in your 2016 Ram Bighorn 1500 all you need is the correct install harness, part # C51458. The truck pigtail is right above where your right foot would be covered in a foam tape.
    view full answer...

  • Where to Mount Curt TriFlex Brake Controller on a 2016 Toyota 4Runner
  • I am going to start with the easy part of your questions if you don't mind! For the Curt brake controller you have the wiring harness needed to plug it into your 2016 Toyota 4Runner is # C51362. As far as placement I have seen the interior of the 2016 4Runner and like you said there is almost no free space! But it looks like to the right of about where your right knee would be there is a vertical space in the center console that appears to be directly in front of the emergency brake
    view full answer...

  • 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
    view full answer...

  • Parts Needed to Install a Trailer Brake Controller on a 2009 Audi Q7
  • If your 2009 Audi Q7 does not have a factory trailer connector at the rear of the vehicle then you will need to install both the ZCI Circuit Protected Vehicle Wiring Harness w/ 4-Pole Flat Trailer Connector and Installation Kit part # 119250KIT and the Universal Installation Kit for Trailer Brake Controller part # ETBC7 in order for a brake controller to work. Trailer brake controllers are universal and can be adapted to fit any vehicle with the correct wiring harness. The correct wiring
    view full answer...

  • Is there a Brake Controller Wiring Harness for a 2008 Mercedes GL550
  • There isn't an aftermarket brake controller wiring harness that will fit your 2008 Mercedes GL550 so you have a couple of options. First you can see if there is an adapter from a Mercedes dealer with one end that plugs into the port under the dash and the other end with just wires. Then you could wire the controller to that adapter harness. The other option is to determine the functions of the pins in that port using a circuit tester such as # 40376 or a meter if you have one. One pin
    view full answer...

  • 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
    view full answer...

  • Recommended Brake Controller Wiring For 2017 Hyundai Santa Fe
  • There is no brake controller harness on your 2017 Santa Fe so it will require some hardwiring. First, you will need part # ETBC7. This plugs into the 4-way connector on your Santa Fe. You will then need to run the additional wires to complete the installation of the brake controller. I have attached a drawing that shows how the wiring is run for the # ETBC7 and the brake controller. The Curt TriFlex Brake Controller, part # C51140 is a proportional controller that will apply the
    view full answer...

  • Where Is the Brake Controller Plug on a 2008 Dodge Ram 1500
  • The correct brake controller adapter plug you are looking for is blue however, it will only have four pins as you mentioned which means the one you have located in not correct. The correct plug you will be looking for and can find in the attached photo is located to the left of the intermediate shaft on the steering column. This plug can also be seen in the attached video. The correct adapter for you if you have a Curt brake controller like the Curt TriFlex Trailer Brake Controller part
    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...

  • 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.
    view full answer...

  • 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.
    view full answer...

Info for these parts were:

Edited by:
Leah B
Written by:
Lindsey S
Expert Research:
Michael H
Updated by:
Kristina F
Updated by:
Isabelle B

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

Product Experts Available Now!

Call 800-298-8924