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  1. Trailer Brake Controller
  2. CURT
  3. Electric
  4. Electric over Hydraulic
  5. Proportional Controller
  6. Digital Display
Curt TriFlex Trailer Brake Controller - 1 to 4 Axles - Proportional

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

Item # C51140
Our Price: $119.95
You Save: $30.00
Trailer Brake Controller
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Shipping Weight: 0.64 lbs
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Simple and compact, this proportional brake controller has an intuitive design that's easy to use. Includes a simple digital display, 9 sensitivity settings, a slide-bar manual override, and built-in safety features. Great Prices for the best trailer brake controller from CURT. Curt TriFlex Trailer Brake Controller - 1 to 4 Axles - Proportional part number C51140 can be ordered online at or call 1-800-940-8924 for expert service.
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CURT Trailer Brake Controller - C51140

  • Electric
  • Electric over Hydraulic
  • Proportional Controller
  • CURT
  • Digital Display
  • Up to 4 Axles
  • Under-Dash Box
  • Dash Mount
  • Automatic Leveling
  • Up to 90 Degrees

Simple and compact, this proportional brake controller has an intuitive design that's easy to use. Includes a simple digital display, 9 sensitivity settings, a slide-bar manual override, and built-in safety features.


  • Brake controller activates trailer brakes in proportion to your vehicle's braking action
    • Automatically adjusts trailer's braking based on deceleration of tow vehicle
  • Simple digital display shows you the braking and sensitivity settings as well as error codes
  • Intuitive controls keep settings within easy reach
    • 9 Levels of boost let you adjust initial braking power and aggressiveness for smooth, safe braking
    • Slide-bar manual override allows you to control trailer sway or stop in emergencies
  • Dynamic power adjustment intuitively gives you the braking output you need
    • Automatically increases power when going downhill and decreases when going uphill
  • Integrated safeguards protect your vehicle, the trailer, and the controller
    • Runs continuous diagnostic checks to alert you to any potential problems
    • Minimizes drain on car battery by entering sleep 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
  • Compatible with ABS brakes, cruise control, low-voltage wiring, multiplex wiring, and PWM systems
  • Automatic leveling lets you mount at various angles
    • 90-Degree vertical mounting range
    • Mounting bracket and hardware included
    • Plug-in, vehicle-specific brake control adapter (sold separately) can be used to reduce installation time on certain vehicles


  • Application: trailers with up to 4 axles (8 brake assemblies)
    • Compatible with electric or electric-over-hydraulic trailer brakes
  • Dimensions: 4" long x 3-1/4" wide x 7/8" tall
  • Mounting range:
    • 90 Degrees vertically
    • 40 Degrees horizontally
  • 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.

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

Use the thumbwheel on top of the TriFlex to set the maximum amount of power that will be applied to your trailer's brakes. How much braking output you need is determined by the weight of your trailer; a heavier trailer will need more power to bring it to a stop. You want to go as high as you can without the trailer brakes locking up. To get more power to your brakes, rotate the wheel to the right. To get less power to your brakes, turn it to the left. The output setting will appear on the digital display when you press the brake pedal or activate the manual override. Once you've set up the brake controller the first time, you shouldn't need to adjust this setting unless the trailer load changes, you switch trailers, or road conditions change.

Sensitivity Setting

Once you have the overall power set, you can fine-tune the power output by adjusting the sensitivity of the internal sensor. This controls the aggressiveness of your trailer's braking, meaning how quickly the brakes reach the maximum braking level. You can adjust this when you're towing heavy loads and you need more umph to bring your trailer to a stop. Your tow vehicle doesn't need that much power to brake in time, but your heavy trailer does. The sensitivity setting gets the braking power to your trailer brakes faster and with more intensity so that it doesn't push your tow vehicle forward. If your vehicle takes too long to come to a stop, increase the setting. If it stops too abruptly, lower the setting. You may also need to adjust the sensitivity based on your own preferences, or when the trailer load or road conditions change.

There are 9 sensitivity levels (boost levels), with 1 being the least sensitive. Move the switch on the side toward you to increase the boost and away from you to decrease it. When you change the setting, the display on the TriFlex will flash the level before reverting back to showing the power output.

Manual Override

Curt Triflex Manual Override

The Curt TriFlex comes with a built-in, easy-to-reach, slide-bar manual override, great for stopping sway or controlling your trailer's momentum in emergencies. To engage the manual override, just push the slide-bar. This will activate the trailer's brakes and brake lights without you having to apply the brakes on your tow vehicle, perfect for limiting trailer movement while you're cruising.

Safety Features

The TriFlex offers key safety features to prevent damage to various components of your towing setup. This starts with built-in protection against shorts and positive and negative power reversal, as well as continous diagnostic checks to alert you to any potential problems as they come up. To minimize the drain on your vehicle's battery, the TriFlex will automatically go into sleep mode when not in use. This feature will turn on after 5 minutes of inactivity and turn off again the moment you press the brake pedal.

Another great way that the TriFlex protects the longevity of your setup is a hold feature that saves wear on your brakes. When you're waiting at a red light, you don't need your trailer brakes on at full power. The longer you sit there, the more they will overheat. But with the TriFlex, any time your tow vehicle and trailer are at a standstill for a prolonged period of time, the controller will reduce the power output to the brakes. This will keep your trailer in place while saving your brakes.

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.

Curt Triflex Automatic Leving, Mounting Angle, Simple Installation

Installation is a snap. With its compact design, the TriFlex will fit easily in your cab. If your vehicle already has a plug-in brake controller wiring harness, just connect the unit to it. Otherwise, you will need to purchase a vehicle-specific wiring harness (sold separately) to plug into. If a harness is unavailable for your vehicle, hardwiring will be necessary.

Installation Accessories

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.

Note: If a custom brake control wiring adapter is not available for your vehicle, either a 20-amp or 30-amp circuit breaker (sold separately) may be required for installation.

Proportional Braking

What is proportional Braking

The Curt TriFlex brake controller comes equipped with proportional braking to give you the best towing experience. Proportional braking means that your trailer brakes mimic your tow vehicle's brakes. If you slam on the brakes in your vehicle, your trailer brakes will activate with the same intensity; if you brake lightly, your trailer brakes lightly too. The trailer's braking is in proportion to your vehicle's braking. This saves wear and tear on the tires and the brakes on both your vehicle and trailer.

The TriFlex uses an internal inertia sensor to detect how your vehicle is braking so it can send the right amount of braking power to your trailer. It measures the inertia of your tow vehicle and activates the trailer's brakes to slow at the same rate. The result is uniform braking across your towing setup. No push-pull action - just smooth, proportional braking every time.

51140 Curt Tri-Flex Proportional Trailer Brake Control

Installation Details C51140 Installation instructions

California residents: click here

Customer Satisfaction Score:

Customer Reviews

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

Average Customer Rating:  4.7 out of 5 stars   (510 Customer Reviews)

Simple and compact, this proportional brake controller has an intuitive design that's easy to use. Includes a simple digital display, 9 sensitivity settings, a slide-bar manual override, and built-in safety features.


Works well and not a bad install with the etrailer videos, my 97 Dodge Ram Sport 1500 5.2 is a””Wood” truck so I installed the truck flex where the ashtray was, works well

Worked so well I bought another for my Silverado
Scott - 08/24/2022


I purchased the trailer brake controller for my 02 Tahoe. Right out of the box it had issues. This controller required a very high setting before it would even work. No less than 7.5 on the screen. Even with all the other settings set to max. The screen also would randomly flash while driving and change the settings. All of my trailers are serviced regularly and brakes start working around 1.5 or so on the other controllers. I have verified all my electrical connections on my vehicle and compared them to another Tahoe, the issue has to be inside the controller. I contacted etrailer about it and they did offer to bench test mine and replace if necessary, but unfortunately I needed to haul trailers almost every single weekend and couldn’t send mine in to wait. The controller has never stopped working which is a plus just very annoying.

I recommend replacing the controller under warranty.
-- Etrailer Expert Jenny N - 09/08/2022


Bought a Kurt TriFlex brake controller. The switch on the side had been broken. So I returned it and received another one. I installed it and my trailer brakes didn’t work. I pulled all four wheels checked all the brakes checked all the wiring spent hours on the trailer found nothing wrong. Then I had to get another controller from the manufacturer as etrailer did not want to send me another. I install that my trailer brakes did not work I inspected everything on my truck and found nothing wrong. I then purchased a prodigy brake controller and everything worked fine I would never buy another curt product in my life


Wonderful product and product support, I bought a second for my newest truck a 2014 Chevy Silverado LT and the installation was very easy thanks to the videos. I put it where the ash tray would go if they still had them and when closed you cannot see it.


I've towed my camper on 4 trips this season and this brake controller has worked without an issue. A very easy setup and then it just works. I live in the mountains and having reliable trailer brakes is a must.I have this installed in a 2011 Nissan Titan.


Great product, plug and play with adapter cord. Install was 10 minutes. Fast delivery with tracking. Price was lower than anywhere else.


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%!

Still using the products no problems, everything’s works great.
Howard S - 04/06/2018


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.

Poorly. The tekonsha prodigy is so much better than this unit.
Jason J - 06/25/2020


All products came fast and the customer service was great!

Product works great!
Jack m - 11/05/2022


Fairly easy to install and set up. I set it up in a 2013 DODGE Durango and pull a 5200# camper with electric brakes. Stopping is very smooth and controlled.

Still like it
Bill A - 04/07/2021


Great controller! Easy to adjust even on the fly. I had the controller adjusted a little aggressive and as I was trying to get out of Buffalo to go south for the winter we ran into some snow accumulation and was able to quickly dial back the controller to avoid locking up on thick snow covered roads. Literally a potential disaster! Very happy with the controller


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.


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.


Watched one of your installation videos. With the factory wiring harness adapter, that came with the Curt Tri Flex controller, installation was a breeze. It took longer to decide where to mount the controller, than it did to make the electrical connections. Used it with my tent trailer on a 2 day trip, worked perfectly. Very pleased with performance and price. See attached photo of finished installation.


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.


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.


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.


Worked as desribed,I had no problem installing after watching video.After taking fuse box cover off my wires were hooked up already,no work to do there.For me a straight up easy install that seems to work great.Drove 130 miles after install ,no issues.


Good communication. Pkg arrived in perfect condition. Will use eTrailer again


this product nearly killed me. in February of 2020 I was towing from Philadelphia area to Miami. Getting off the ramp of 95 at S.O.B. I depressed the slidding button for added braking and I heard a tiny snap and the button stuck in. we skidded to a stop and put flat spots on out tires. turns out the return spring inside snapped off its tiny plastic tab and the brakes locked on. cheap [foreign] crap strikes again. when will we pleas make this stuff in amarica again ??

Andrew S - 10/01/2021


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!


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.


Great product.Works as described. The instructions were well written and video was helpful as well.Would recommend to anyone looking for a good break controller.

Works great.No issues so far other than the little light that lets you know its on.Wish I could shut it off.My truck sets a long time between starts so it probably helps drain the battery a little.Great product and instructionsvideo,easy to install.I would by it again if I ever need one.
Monty - 09/17/2021


Produce arrived the next day and was installed that day. Great customer service. Highly recommend! Purchased trailer controller for a rv camping trip.


I haven't been able to use this yet on a trailer with brakes, but seems to work as described so far. Install was initially a little concerning as the unit's measure input resistance was 1.9 ohms, while OFF). However, once actually connected, and not doing anything, it draws only 22 mA (indicating about 550 ohms, when connected to 12V). This should allow about 2 months of standby on a healthy battery before problems starting might develop. I think it will work out fine. I liked the more intuitive controls on this unit than many of the other brake controllers. Time will tell.....

Show More Reviews

See what our Experts say about this CURT Trailer Brake Controller

  • How to Install a Brake Controller on a 2014 Ford F-150 with Factory 7-Way
    A brake controller, whether it is a Curt or a Tekonsha or another brand, will plug into the same place on your 2014 Ford F-150. So I have included a link to a video showing installation of a different brake controller on a 2013 Ford F-150 and the process will be basically identical on your 2014. The connection point on the vehicle is located behind the center console, to the left of the radio. You will have to remove that panel and the connector will be behind it.
    view full answer...
  • Troubleshooting Curt Tri Flex Brake Controller that Locks up Trailer Brakes
    L.1 is the lowest sensitivity that the Curt Tri-Flex part # C51140 can be adjusted down to. However, you can also adjust the overall brake output power with the output control. The output control thumbwheel can be adjusted from the lowest setting all the way up to the highest of 9.9. If you have the controller adjusted all the way down on both of the mentioned settings and it is still locking up then I would assume you have the brake light circuit shorting out to the brake output circuit...
    view full answer...
  • Curt TriFlex Brake Controller Output Numbers Jump when Going Over Bumpy Roads
    The Curt Triflex # C51140 does not have a pendulum. That is an older technology that is not used that much any more. But it still could have been caused by the truck bouncing on the road if it was severe enough. It could also have been an electrical anomaly caused by flex between the truck and trailer connectors or the wiring on the brake magnets moving more than normal from the bouncy road conditions. Make sure the truck and trailer side connectors are clean and free of corrosion inside...
    view full answer...
  • Curt Triflex Brake Controller Displays 05 and Trailer Brakes Not Working with Brake Pedal
    On Curt brake controller # C51140 there is a 20 display so if the display is upside down is would look like 02 or 05. That message either indicates that a trailer is connected and the brakes are activated or, if it is flashing, that means it is in output adjustment mode waiting for the power output to be adjusted. Try adjusting the power to 2.1 to see if it displays 1.2 or 1.5 and if so then the display is showing upside down. I also recommend cleaning the vehicle and trailer side connectors...
    view full answer...
  • Can the Top of the Fuse Box/Power Distribution Box Be Opened Safely on a 2014 GMC Yukon
    You have to be careful with the fuse box or power distribution box on your 2014 GMC Yukon because if you lift that handle (or the whole box) more than 3/8 of an inch it will become disconnected from the vehicle and you will have to have it towed to a GMC dealer to get the vehicle working again! You can take the top cover off though to access the fuses and relays without any issue. You just want to avoid pulling the whole box up. I have included a link to our help article on installing...
    view full answer...
  • Curt TriFlex Brake Controller Turns On with Brake Pedal Even If 2013 Kia Sorento is Turned Off
    Yes. Brake controllers such as # C51140 are connected, in part, to the brake switch on the vehicle. When you step on the brake pedal it sends power along the red wire which is input to the controller telling it you are stepping on the brakes. On some vehicles, like yours, the brake lights will light up even if the vehicle is turned off. So it does sound like everything is working properly.
    view full answer...
  • Should there be a Small Amount of Voltage on Curt Brake Controller Red Wire on 2013 Kia Sorento
    Yes that is normal. The power you are seeing is dead voltage, no amperage draw, and is normal for Curt brake controllers like the TriFlex, # C51140, on your 2013 Kia Sorento.
    view full answer...
  • Curt TriFlex Brake Control Shows Settings When Not Connected to Trailer or Locks Up Trailer Brakes
    It sounds like the sensitivity is set high. The closer the sensitivity lever is to the driver, the more aggressive the brakes will be. There could also be a short in your vehicle side trailer connector. Check the vehicle and trailer side connectors for any dirt or corrosion inside and out. A short could cause some of these problems and others. Another possible problem is how the controller is mounted. The controller can only be mounted 70 degrees nose up or 20 degrees nose down. The...
    view full answer...
  • Troubleshooting Curt TriFlex Brake Controller Showing Overload Error
    This The OL error you're seeing means that there is a short somewhere in the brake output circuit, which is the blue wire that exits the rear of the controller. The usual cause of this is a corroded or damaged trailer connector, but because this is a recent installation on an almost new vehicle, that's probably not the case. In the install, you ran the gray two-wire cable from the rear of the vehicle. The white wire in the cable should be connected to the blue wire on the 7-way connector...
    view full answer...
  • What Problems Does the Curt Triflex Brake Controller Have with 7-Ways With LED Test Lights
    What happens is that the load that LED puts on the brake output circuit tricks the brake controller into thinking that there is a trailer connected and the brake controller will start activating regardless if there is a trailer connected or not. Technically it would work just fine with a trailer, its just that it will always activate regardless if there is a trailer back there or not. I attached installation instructions and an install video for you to check out also.
    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...
  • Brake Controller Recommendation for a 2012 Tiffin Allegro QFA34 towing a Master Tow Dolly
    The Curt Triflex part # C51140 that you referenced would do an excellent job as a brake controller in your 2012 Tiffin Allegro QFA34 towing a Master Tow Dolly part # 80THDEB. You'll have to hardwire the brake controller in, which isn't hard. Check out the FAQ article I attached on installing a brake controller from scratch that will detail the installation.
    view full answer...
  • Curt Triflex Trailer Brake Controller Shows Power All the Time on Blue Wire
    You should only be seeing 12 volts on the blue wire on the brake controller, # C51140, when the manual override is used. If there is constant power all the time then there is either something that is miswired or a problem inside the controller and it will need to be replaced. Brake controllers do send back a minimum amount of voltage to check for a connected trailer but it should not be enough to activate the brakes. In the truck cab you will need to sever the blue wire several inches...
    view full answer...
  • Troubleshooting Curt Fri-Flex Brake Controller Installation in 2014 Nissan Frontier
    I suggest you disconnect your trailer and test both the tow vehicle and trailer independently. Please note that if your vehicle's 7-way trailer connector has LED test lights built into it, then the TriFlex brake controller will not be compatible. First you can check the signals going into and leaving the Tri-Flex. Apply a circuit tester like # 40376 to the black wire at the controller. This wire carries 12V power to the Tri-Flex and should be hot at all times, even when the vehicle is...
    view full answer...
    Image 1 for
  • Curt Trailer Brake Controller Displays Gibberish when Brake Pedal is Pressed
    The brake controller may be trying to tell you something. Take a look at the picture I have included and if what it is displaying is any of these then it is trying to indicate there is a problem. It also could be variable voltage on the input (red) wire or the sensors inside are unsure just how much braking is needed. Make sure the controller is not tilted or turned to one side. You also may need to adjust the sensitivity some (see instructions link). You will also want to make sure...
    view full answer...
    Image 1 for
  • Curt Triflex Controller Shows Decimal Point and 2.o
    For the Curt Trifles the " . " means that the controller is in standby mode with not trailer connected. "2.0" flashing constantly means that it is in output adjustment mode. Have you tried connecting to a trailer to see if it works or not? You were correct in not wiring the CHMSL wire to the 7-way so it sounds like you may have everything set up properly. You might run through the setup process for the controller that is in the install instructions link I attached to see if it just...
    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...
  • Should Curt TriFlex Brake Controller be Drawing 21.5 Milliamps in Standby Mode
    All modern brake controllers including the Curt TriFlex # C51140 draw a few milliamps at idle. The Curt controllers are slightly different in their circuitry and can draw a little more than other brake controllers. This power draw is normal and it would take months of the vehicle just sitting, not ever running, for it to drain a battery.
    view full answer...
  • Curt TriFlex Brake Controller Display Shows Only L.
    The L. display should show up on the Curt TriFlex brake controller, # C51140, when it is plugged in. When you are installing the controller, the trailer should not be connected. The lever or button on the left side of the controller is the sensitivity adjustment. The L. should change when that lever is moved. You can also try resetting the controller by unplugging it for a few minutes and then plugging it back in (without the trailer connected). If these things do not fix the issue then...
    view full answer...
  • Troubleshooting Error Code A.E. on Curt TriFlex Trailer Brake Controller C51140
    The operating instructions for the Curt Triflex brake controller # C51140, which are linked for you, indicate on page 19 that if the unit displays the error code A.E. this indicates an internal fault with the controller's accelerometer. This is not a serviceable problem and the unit should be replaced or referred to Curt for warranty service under the terms of the limited lifetime warranty. You may care to review the linked article on brake controllers.
    view full answer...
  • Curt TriFlex C51140 Brake Controller Displays 9.9 With Brake Pedal When Trailer is Disconnected
    The fact that your Curt # C51140 TriFlex brake controller is displaying 9.9 on the LED display doesn't indicate a problem, it's perfectly normal and indicates the controller is working properly, according to the instructions. On page 5 of the instructions, it states that if a trailer isn't connected the output setting (adjusted using the dial on the controller, adjustable from .5 to 9.9 is flashed on the display when the brake pedal is pressed or the manual brake switch is pressed. I've...
    view full answer...
    Image 1 for
  • 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...
  • 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...
  • 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...

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