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Curt TriFlex Trailer Brake Controller - 1 to 4 Axles - Proportional
Universal Wiring Adapter for Curt Trailer Brake Controllers

Part Numbers: C51140,C51515


Our Price: $103.82

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C51140 - Digital Display Curt Brake Controller
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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

Universal Wiring Adapter for Curt Trailer Brake Controllers
part number: C51515

This wiring adapter is designed for vehicles that do not come equipped with a factory brake control wiring harness port. One end plugs into your Curt trailer brake controller while the other end splices into your vehicle's wiring.


  • Universal wiring adapter eases installation of your electric trailer brake controller
    • No need to wire brake controller directly to your vehicle
  • Wire end splices into your vehicle's wiring
    • Use on a vehicle that does not have a factory tow package or on one that has a brake control harness but is not equipped with a plug-in port
  • Connector end joins with the plug on your electric brake controller
    • Compatible with time-delayed and proportional brake controllers from Curt
    • Simple to plug and unplug control for removal
  • 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. Usually when this is done, a port is installed at your dash so that you can easily plug in a brake controller. However, if no port is present, you will have to splice into your wiring.

With this universal adapter, you can install your Curt brake controller without having to wire the controller directly to your vehicle. If your vehicle has a factory tow package, just splice the pigtail end of the adapter into your vehicle's factory brake control harness wiring, and then plug the other end of the adapter into the controller. If your vehicle doesn't have a factory tow package, you'll have to hardwire the pigtail end of the adapter into your vehicle's wiring. Because only the adapter is hardwired to your vehicle, you can unplug and remove your brake controller at any time to transfer it to another vehicle or securely stow it away.

If your vehicle is not equipped with a factory tow package, you will need to purchase additional equipment to ensure that the signals from your brake controller are sent to your trailer's brakes. We recommend's exclusive 7- and 4-way brake control installation kit (ETBC7 - sold separately).

51515 Curt Universal Quick Plug Brake Control Adaptor Harness with Pigtail

California residents: click here

Customer Reviews

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

Universal Wiring Adapter for Curt Trailer Brake Controllers - C51515

Average Customer Rating:  4.8 out of 5 stars   (450 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. This wiring adapter is designed for vehicles that do not come equipped with a factory brake control wiring harness port. One end plugs into your Curt trailer brake controller while the other end splices into your vehicle's wiring.

- 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


- C51515

by: Robert09/30/2018

Product was easily located on website and was exactly what I was looking for. I had forgotten to take off of my old vehice before I sold it, so this allows me to plugin my Curt brake controller without having to cut the connector off of it. 570389

- 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: 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: 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: 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: 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: 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: 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: 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: 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

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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: 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: 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: 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: Jared S.10/12/2017

The trailer brake worked out very well. Installation was a little difficult for someone with no experience, but the videos on etrailer were great. My only issue would be that I only had about a foot of spare cable left at the end of the install, a few more feet would have helped me feel more comfortable. Otherwise, great product and site. Having all the right equipment and videos appropriate for my Jeep were essential. 442038

- 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: Larry H08/23/2017

I haven't used it yet, because I cannot seem to get it wired correctly. It had good reviews and my son purchased this unit for his new truck and trailer about 6 months ago. He personally recommended it for me. But I have yet to see a video by etrailer or anyone else showing exactly where the brake light wire is under the dash for my '95 Suburban. I have paid 2 techs to wire the red wire.....wrong. 424375


Larry, after reviewing your order notes today, I see that your 3rd mechanic was able to find the wire. Some models do have the brake blue and hot lead orange or red wires already ran from under the hood to the end of the drivers side frame rail. However, as you know, these wires are hard to access and additional wire will still be needed. Part # ETBC7
Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires
is still recommended.

-- Laura E - 08/30/2017


- 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: 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: 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: Steven08/29/2018

I wasn't very pleased with this brake controller. It seemed to frequently require resetting, which involved stopping, getting out and unplugging/replugging the brake cable. I was never able to get a good understanding of the controls either - there was a dial for gain and a slider for "aggressiveness" (huh?). Also, after using it for about 10 months, I thought the brakes on my trailer needed replacing - it would brake some, but not much. About that time I bought a new truck with built-in brake controller and the trailer brakes worked great again. Had to be due to the controller... 559619

- C51515

by: BiscuitsNGravy10/21/2013

I own a 2008 Chevy Silverado. I ordered the brake controller - C51515 and the universal wiring adapter on Friday and received it on Tuesday. My friend who is a mechanic installed it in about an hour on Wednesday. I towed my camper trailer to Lincoln, NE (about a 5 hour trip) on Thursday and returned on Sunday. After reading the settings instructions, all stops were made smooth and firm. was great and the Curt Trailer Brake Controller is excellent! 104632


I have enjoyed the use of the electric brake controller. The stops are always safe and smooth. Im glad I got it for my truck and Ive never had a problem with it. I just need to get out and use my camper more! The initial contact with was very favorable and I will do business with them again when I need something for my trailers or tow vehicles.

BiscuitsNGravy - 10/21/2014


- 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: 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: 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: OEM09/24/2017

The screws for the bracket did not fit into the plastic bushings in the bracket. I have got hooked this up to a trailer with brakes, yet, but everything else seems to work, including the adapter for my Silvy1500. Note that this review bears no negativity on etrailer, but he manufacturer of the brake controller. Stop letting China manufacture our goods and get better product reviews. I have had good experiences with, they always ship fast and deliver quality installation guides. Kudos to them! 435970

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by: Robert07/15/2018

Item is smaller and lighter than expected. Easily mounted using existing dash screw. Pigtail wire kit that was also ordered here made installation a snap. I like the display and the ability to manually apply trailer brakes and increase braking force on the fly. Less than a 5 minutes install. Installed only, haven’t used it yet. Will have to update later. Rig is 2007 Dodge Ram 2500 4X4 CTD. 542058

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by: Kent E.06/05/2016

Wiring up a brake controller can be tricky. Routing the wire from the hitch to the firewall and finding the right wire on the brake are the hardest part, but etrailer will do their best to help. Consider running the wire inside the car along the door bottom just under the carpet. This avoids problems with the tie-wraps under the car -- there just isn't anywhere to tie wrap under the middle of the car. Use "loom clamps" ordered separately to solve this problem, if you go under the car. To find the right brake wire without cutting insulation, use the fish wire from the hitch install to contact the end of the wire inside the connector (from the back). Then touch the fish wire with the continuity tester and apply the brake pedal. My brake had a four wire connector and I found the right one on the second try. If you find a hole in the firewall with a rubber plug in it, don't discard the plug. Make a short slice in it with a razor blade and push the wires through. You may have to work the wires around to get them through the carpet. Be patient. Be sure to watch all the videos and allow plenty of time, taking a break before you tackle the hard parts. Rest assured that doing it yourself is better than allowing UHaul to cut corners and charge you labor. :-) If you are doing the hitch install and four-wire harness, those are much easier. If you are installing the hitch alone, be sure to have a magnet wand for when you push the bolt up into the frame rail. If I had it to do again, I would use a little electrical tape to hold the bolts down so a slight bump wouldn't knock them up. 257414


Ive not had any trouble with the hitch or the brake controller. I can tow my tear trailer anywhere I want and the hitch protects my mufflers from damage when I go offroad. Nice extra benefit.

Kent E - 01/23/2018


- C51515

by: George D10/17/2015

good quality and works with brake controller so you don't have to rig it up its all there glad i bought it thanks 230175


Very easy to do still working great

George D - 10/16/2016


- C51140

by: Bryan07/15/2018

This was my first brake controller. Installation took me about 40 minutes. Having the truck prewired means its as simple as plug and play. As soon as I powered it up it worked, and calibration once I was hooked up to a trailer took just a few minutes. So far I'm pleased. I'm still working on the right settings but I would definitely recommend this unit. Also staff at Etrailer were very helpful. The first controller I ordered had the cable out of stock. They emailed me right away and helped me pick one out that was in stock and arrange the two day shipping I needed. This was on a Friday evening, so many places would have waited until Monday to let me know. 541910

- 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

- C51515

by: Mainly Dave07/22/2015

Recently used this kit to install electronic brakes on a 2014 FJ Cruised. Absolutely essential and worth every penny! Instructions straight forward and everything included! 213491


Have been using this product for a year now. Commonly haul 2-3 tons. Absolutely no problems and the braking system works well. Adjustments based on load are easy. Highly recommend!

Mainly D - 07/22/2016


- C51515

by: Ted07/03/2014

I purchased the wiring harness to aid with hooking up the Curt Brake Controller I had previously purchased. The shipment was fast. The product was perfect. The on-line installation video was perfect and allowed me to complete the installation like a professional. I have never purchased anything from .... but should I ever need anything in the future, they will be my first choice. 139007


Perfectly. No issues at all with wiring or controller.

Ted - 07/03/2015


- C51515

by: Frank S02/14/2014

this went into my VW Touareg which requires the relay modification described in the Technical Bulletin. Because ground and +12V is already present in the harness, instead of running additional cables, I soldered the relay right into the cable, making it a clean plug and play setup which is 100% removable. I also bought the VW housing and wire kit to complete the install 116584

- C51140

by: Bill S10/09/2017

Great service!!! Product was just as de scribed. 440846


We still love it. Thank you for reaching out!!!!

Bill S - 10/10/2018


- C51140

by: Rick10/10/2018

Works very well ! 573332

- C51140

by: Jonathan10/23/2018

The brake controller arrived within 2 days with standard shipping! I was able to install it correctly the first time using the instructions provided. I also purchased the Curt Install Kit For Trailer Brake Controller - 7-way (product C57186) to run wiring from the brake controller to the trailer plug. I am extremely happy with this purchase because I am now able to use trailer brakes with our camper (2005 Chevy Colorado mated with a 3,300 lb. camper). During the first trip I adjusted the braking power down several times. I highly recommend this product because it has performed very well for me and made traveling with the camper much safer. 576813

- C51515

by: Trevor10/03/2018

Simple and easy to install. Helps make a cleaner look 571173

- C51140

by: Curtis09/28/2018

Product came as advertised. Instillation was straight forward. I don't have a trailer yet, so I have now way of testing it out. 569611

- C51515

by: Jonathan K.10/20/2018

I am completely satisfied. The package arrived quickly and I was able to install on my truck the same day with help from the installation videos. I will definitely purchase from in the future. I have saved money by spending with and doing the upgrades myself. 576833

- C51140

by: Jonathan K.10/20/2018

I am completely satisfied. The package arrived quickly and I was able to install on my truck the same day with help from the installation videos. I will definitely purchase from in the future. I have saved money by spending with and doing the upgrades myself. 576834

- C51515

by: Jeff09/18/2018

made wiring painless 566423

- C51140

by: Paul09/14/2018

Seems to work very well.smooth controls,and easy to adjust. 565181

- C51140

by: William09/10/2018

Extremely easy install, works perfect! 563481

- C51140

by: Dave08/27/2018

Great brake controller and after a year of use no issues. I like the slim low profile design and made installing easier. 558924

- C51140

by: George08/26/2018

This works pretty well for my 10K lb Hudson equipment trailer. I've never used a brake controller before and this was pretty simple to operate. It plugged right in to a wire harness under the dash of my 2003 Ford Expedition. The setup instructions were thorough but sounds a little more complicated than the actual usage is. Overall very easy to use. 558237

- C51140

by: Monty08/21/2018

Im a happy guy thumbs up. 556191

- C51140

by: Robert08/21/2018

Packed well and delivered on time. Easy installation, and Etrailer always provides additional resources if you get stuck and need help. Great company 555985

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Ask the Experts about this 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...

  • 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...

  • 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...

  • 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
    view full answer...

  • 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
    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
    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...

  • 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...

  • 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
    view full answer...

  • Meaning of Error Code RC with Curt Tri-Flex Trailer Brake Controller C51140
  • I could not find purchase history for a brake controller based on your email address but I do note that you referenced a question regarding the Curt Tri-Flex # C51140. With this brake controller the code RC indicates that the unit needs to be recalibrated. You can accomplish this by unplugging the trailer connector from the tow vehicle, waiting a minute or two and then re-connecting it. I linked the installation instructions and troubleshooting guide for this item for your reference.
    view full answer...

  • Constant Voltage on 12V and Brake Controller Output Wire with Curt TriFlex Trailer Brake Controller
  • When testing the wire functions after installing the Curt TriFlex Trailer Brake Controller # C51140 and Wiring Harness # C51515 in your 2014 Toyota Sienna, it is normal for both the 12V and brake lights on a tester like # TR20117 to light up without actually activating the brakes. This is because the brake controller sends out a small trace current to look for a completed circuit. I have attached a demonstration video on a similar 7 Way Trailer Connector Vehicle Tester # TR20117 that shows
    view full answer...

  • 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.
    view full answer...

  • Curt Brake Controller Flashes a 6.6 on the Display when no Trailer is Connected
  • If what you are seeing on the Curt brake controller # C51140 is L6 then that would indicate that the controller is indicating low voltage on the tow vehicle system. But if it is actually reading 6.6 or 6.7 then that is the power output level and it could be showing that when going over bumps if there is a loose wire somewhere. Given that the truck and trailer are new it is not likely a corrosion issue in either trailer connector. I recommend running through the set up procedure again
    view full answer...

  • Curt Brake Controller Flashes Numbers when Braking and Not Towing with a 2011 Ram 1500
  • Curt brake controllers such as # C51140 can be very sensitive and it is not uncommon to get something on the display with no trailer attached. But what I recommend is to make sure the 7-Way connector at the back of the truck is clean and free of corrosion and moisture inside where the wires attach and outside on the pins. Corrosion or moisture can cause a short and cause the brake controller to do strange things.
    view full answer...

  • Troubleshooting OverLoad Code on Brake Controller With Trailer With New Wiring
  • It sounds like you have bad trailer brake magnets on your trailer. Having a bad magnet can cause the problem you described and based on what you mentioned it would be the most obvious issue. I attached a help article that details how to troubleshoot trailer magnets.
    view full answer...

  • 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
    view full answer...

  • Troubleshooting Curt TriFlex Brake Controller Showing Flashing DC And Locking Brakes
  • I reached out to my contact at Curt and the DC flashing on your Curt TriFlex Trailer Brake Controller # C51140 is showing that your trailer is disconnected from the brake controller. This code is telling you that there is an issue between the contoller and your trailer brakes, that there is a short somewhere. This could be corrosion at the connection, a nick in the wire somewhere or a short on the trailer itself. I recommend checking your controller first. Using an incandescent
    view full answer...

  • 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
    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...

  • Brake Control Harness # 51515 Installation Process in 2008 and 2013 Chevrolet Silverados
  • The Curt Brake Controller Harness you referenced, part # C51515, can be used for both the 2008 and 2013 model years of the Chevrolet Silverado since it is a universal-fit harness. For your 2013 Silverado you will want to follow the procedure outlined in the linked article. Please refer to the photo provided which shows the vehicle tow package wiring that can be found under the dash. You will connect these wires to the leads on the Curt harness as per the article, using butt connectors
    view full answer...

  • Brake Controller Recommendation for a 2012 Mercedes GL450
  • In order to install a trailer brake controller on your 2012 Mercedes GL450 it will require hardwiring in the controller unless the Mercedes dealer has a wiring harness specific for a brake controller and your vehicle. If they do then you will need to wire in the controller to the Mercedes harness by function. On a brake controller, the wire functions are as follows: White is ground Black is 12 volt power Blue is output to the trailer brakes Red is input from the brake switch On
    view full answer...

  • Troubleshooting Curt Brake Controller Installation in 2007 GMC Sierra New Body Style
  • First I suggest making sure you are testing the brake circuit pin on your Sierra's 7-way trailer socket. If you refer to the linked photo of a trailer connector you will note the brake controller's output is carried on the pin at the 5:00 position; the ground is at the 7:00 position. If you happened to test the 12V auxiliary power circuit, carried on the pin at the 2:00 position, it will have power at all times. I see that you purchased Curt Universal Wiring Adapter # C51515 which
    view full answer...

  • Parts Needed to Install a Trailer Brake Controller on a 2006 Jeep Commander
  • For a 2006 Jeep Commander that did not come with a factory installed 7-Way trailer connector, you will need a few items to install a trailer brake controller. First, if your Commander does not already have a 4-Way, you will start by installing one using # 118408. I have included a video showing a typical installation for you. Then you would need a 4 and 7-Way installation kit # ETBC7. This will provide the 7-Way and the wiring and accessories needed to install a brake controller. I have
    view full answer...

  • Adapter for Curt Venture Brake Controller on VW Touareg
  • In order to use the Universal Wiring Adapter for Curt Trailer Brake Controllers # C51515 with your Curt Venturer # C51110 brake controller, you will need additional parts from your Volkswagen dealer. Please see the attached help article on installing a brake controller in 2005 and up Volkswagen Touareg's. It states in part: "To install a brake control on a 2005-current Volkswagen Touareg or Porsche Cayenne using the factory brake control connector, you will need to assemble a brake
    view full answer...

  • Wiring Adapter for Curt Electric Brake Controller on 2016 Toyota Tacoma
  • We do offer the Universal Wiring Adapter for Curt Trailer Brake Controllers # C51515. This adapter will connect with the plug on the back of the Curt electric brake controller on one end and the other end will allow you to hardwire install the brake controller. If you need to add a 7-Way to your tow vehicle, the # C51515 adapter will work well with the Universal Installation Kit for Electric Trailer Brake Controller # ETBC7. The instructions for this hardwire installation are linked
    view full answer...

  • How to Install the Curt Wiring adapter # C51515 on a 2008 Chevrolet Silverado
  • To install the Curt Wiring adapter # C51515 in your 2008 Chevrolet Silverado you will need to hardwire it under the dash. To be sure that the wire bundle you found under the dash is the correct set of wires I would check the white tag for any indication as to what each wire is for. If none of them have labeling then it would be best to test their functions with a circuit tester like part # ALL640595. You will then connect the following wires from the Curt adapter to the following functions: Blue
    view full answer...

  • Brake Controller and Install Harness Recommendation for a 2006 Jeep Commander
  • The correct Curt brake controller install harness you will need for your 2006 Jeep Commander is the part # C51515 that you referenced. I would recommend you go with a proportional brake controller with it like the Curt Triflex part # C51140 as it will sense the amount of braking you are applying with your vehicle and will provide a proportional amount of braking power to the trailer. Some models will require a wiring kit to run wire to the battery. This may require drilling a hole
    view full answer...

  • Troubleshooting Curt Venturer Brake Controller Installed on 2011 Dodge Ram 1500 Pickup
  • Getting a single green LED on the display indicates that there's no trailer connected. Since you're getting this with the trailer connected, it would seem to indicate that the brake controller isn't 'reading' the trailer for some reason. The most common reason for this to happen would be a dirty, corroded or damaged connector on the vehicle or the trailer. Examine the trailer connectors, and ensure everything is clean. If you see any white or green corrosion on the pins or sockets of the
    view full answer...

  • When Does Brake Output Circuit of Vehicle 7-Way Have Voltage
  • The brake output circuit on a 7-way (5:00 pin) will only have as much voltage on it as the brake controller is sending. Typically this going to depend on the amount of gain selected on the controller and other factors like brake controller style and ramp up speed of the controller. The only time the circuit would have voltage without the brake pedal being applied would be if you had the manual override lever of the controller slid. I attached a couple help articles on brake controllers
    view full answer...

  • Troubleshooting Brake Controller Not Allowing Truck To Start
  • For your 2014 Chevy Suburban, no plug is present under the dash, but the needed wires are already run. You will connect the brake controller wiring with the vehicle wiring already present under the dash using the Universal Wiring Adapter for Curt Trailer Brake Controllers # C51515. It seems the 2007 to 2013 brake controller wiring was carried over into 2014 for your vehicle. I've attached and article to assist. The issue you are experiencing is most likely because you have a plug
    view full answer...

Info for these parts were:

Test Fit:
Joe V
Edited by:
Leah B
Photos by:
Jackie C
Expert Research:
Michael L
Video by:
Andrew K
Written by:
Lindsey S
Expert Research:
Michael H
Installed by:
Jeff D
Expert Research:
Jameson C
Video Edited:
Joshua S
Test Fit:
Nicholas E
Video Edited:
Jacob T
Test Fit:
Rick A
Expert Research:
John H
Updated by:
Adele M
Video Edited:
Andrew L
Expert Research:
Adam R
Video Edited:
Kathleen M
Test Fit:
Shane T
Expert Research:
Rachael H
Expert Research:
Jeffrey L
Video Edited:
Sue W
Test Fit:
Randy B
Video Edited:
Chris R
Updated by:
Sarah W
Updated by:
Amanda M
Video Edited:
Zach D
Test Fit:
Brent H
Updated by:
Kristina F
Video Edited:
Dustin K
Photos by:
Jim W

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