Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed
Universal Wiring Adapter for Curt Trailer Brake Controllers

Part Numbers: C51120,C51515

Retail:$90.56

Our Price: $48.20

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Brake Controller C51120 - Automatic Leveling - Curt
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Product Images

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Brake Controller C51120 - Automatic Leveling - Curt
Accessories and Parts C51515 - Universal - Curt
Curt Accessories and Parts - C51515
Brake Controller C51120 - Up to 4 Axles - Curt
C51515 - Brake Controller Wiring Adapter Curt Brake Controller
C51120 - Digital Display Curt Time Delayed Controller
Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed Electric C51120
C51120 - Electric Curt Brake Controller
Curt Time Delayed Controller - C51120
Curt Time Delayed Controller - C51120
C51120 - Digital Display Curt Time Delayed Controller
Curt Time Delayed Controller - C51120
Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed 360 Degrees C51120

In Use/Installed

Brake Controller C51120 - 360 Degrees - Curt on 2014 Jeep Grand Cherokee
C51120 - Electric Curt Brake Controller on 2014 Jeep Grand Cherokee
Curt Discovery Trailer Brake Controller - 1 to 4 Axles - Time Delayed 360 Degrees C51120 on 2014 Jeep Grand Cherokee
Curt Brake Controller - C51120 on 2014 Jeep Grand Cherokee
Universal Wiring Adapter for Curt Trailer Brake Controllers Plugs into Brake Controller C51515 on 2016 Ford Transit T350
Curt Accessories and Parts - C51515 on 2016 Ford Transit T350

Customer Photos




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

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

Features:

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


Specs:

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


Time-Delayed Braking

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


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


Built-In Controls for Adjustable Power

Curt Discovery Controls and Components

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

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

Output Control

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


Sync Setting

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


Quick, Simple Installation

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


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


Installation Accessories

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


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

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

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


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



51120 Curt Discovery Time Delay Trailer Brake Control





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.

Features:

  • 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 etrailer.com's exclusive 7- and 4-way brake control installation kit (ETBC7 - sold separately).



51515 Curt Universal Quick Plug Brake Control Adaptor Harness with Pigtail





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


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




Video Transcript for Curt Brake Controller C51120 Review

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

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

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

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

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



Customer Reviews

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

Universal Wiring Adapter for Curt Trailer Brake Controllers - C51515

Average Customer Rating:  4.8 out of 5 stars   (392 Customer Reviews)

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

- C51120

by: Don10/17/2018


Excellent customer service very professional. Fast and easy shipping. Very knowledgeable staff. I will be back. 575040



- 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



- C51515

by: Trevor10/03/2018


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



- C51120

by: Chris04/28/2018


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



- C51120

by: Dale07/21/2018


Purchased this controller for limited use. Really like the vehicle specific plug adaptor that came with it. Makes for a quick clean install. Clean compact design and easy to use. 544267



- C51120

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


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



- C51120

by: Cynthia07/14/2018


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



- C51120

by: Justin08/02/2016


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



- C51120

by: Bob R02/05/2016


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


Comments

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

Bob R - 02/04/2017

22382

- C51120

by: Paul07/05/2018


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



- C51120

by: George D10/17/2015


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


Comments

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

George D - 10/16/2016

21545

- 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


Comments

Very easy to do still working great

George D - 10/16/2016

21546

- C51515

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


Comments

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

33496

- C51120

by: Raymond L.05/30/2015


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


Comments

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

Raymond L - 05/29/2016

18132

- 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


Comments

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

19561

- 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. Etrailer.com was great and the Curt Trailer Brake Controller is excellent! 104632


Comments

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 etrailer.com 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

7356


- C51515

by: Jeff09/18/2018


made wiring painless 566423



- 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 etrailer.com .... but should I ever need anything in the future, they will be my first choice. 139007


Comments

Perfectly. No issues at all with wiring or controller.

Ted - 07/03/2015

13016

- 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



- C51120

by: Randy G01/04/2014


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


Comments

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

Randy G - 01/05/2015

8405

- C51120

by: Bobby04/30/2016


Easy to install and Thanks for the help. 247727


Comments

Perfect.

Bobby - 04/30/2017

23537

- C51515

by: CD08/10/2017


price was very reasonable, free shipping is great and the how to videos are excellent. 418528


Comments

Im pleased with them, no problems.

CD - 09/01/2018

43071

- 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 etrailer.com in the future. I have saved money by spending with etrailer.com and doing the upgrades myself. 576833



- C51515

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 556678



- C51515

by: Ross08/17/2018


Easy to use, great customer service. 554693



- C51515

by: Gary H.08/14/2017


Perfect part, great price and delivery. 420103


Comments

Awesome Product and Awesome Companuy! Zero regrets.

Gary H - 08/14/2018

42297

- C51120

by: Kenneth08/06/2018


Worked very well 550732



- C51120

by: Joe07/22/2018


Product works great just as described . Did have a little trouble installing it but otherwise no issues. 544469



- C51515

by: Noob07/20/2018


Great product, makes a brake controller install easy. 543674



- C51120

by: George07/14/2018


Product is what fits my truck for proper operation. Compact and easy to use. Price is right and is easy to install. 541792



- C51515

by: Robert07/10/2018


This was my first purchase from etrailer. I will definitely come back again and again. Fast shipping. You all are great. Thank you so much. 540026



- C51120

by: Jon06/21/2018


Exactly what I wanted 524866



- C51120

by: Matt06/18/2018


Works very well! Nice product and easy install! Very satisfied! 523370



- C51515

by: Matt06/18/2018


Works very well! Nice product and easy install! Very satisfied! 523773



- C51515

by: Peter06/17/2018


Excellent fantastic service. 522824



- C51515

by: Don06/11/2018


Great quality product ! 520809



- C51515

by: Cliff06/08/2018


Worked great and went on very easy. Feels a lot better to tow a trailer with brakes!! 519530



- C51120

by: Debra06/05/2018


Bought this for my father for father’s day gift. Worked great. He was glad to get it. 517633



- C51120

by: Luke06/04/2018


Installed in about 5 min. Arrived ahead of schedule and instruction videos were great. Will buy All trailer stuff here in future. 517464



- C51120

by: Tim L.06/04/2018


Good quality product ( electric trailer brake control) and fast delivery!! Very satisfied. Do recommend!! 517385



- C51515

by: James06/01/2018


Easy install, nothing to it! 515410



- C51120

by: Jeremy05/30/2018


Easy to install and does what I need it to. 514072



- C51120

by: Thanh05/30/2018


The break controller and dual plug in adaptor worked great for my 2014 QX60. Easy to install and worked perfect. 513770



- C51515

by: Steve07/26/2017


Haven't installed yet. Looks pretty sol id 411028


Comments

Super easy install.

Steve - 07/26/2018

41535

- C51515

by: Mark05/26/2017


Works as described. Hooked up to the universal installation kit without any problems. You have to have ability to use tools and crawl under the car and under the dash to get everything hooked up. Not for the faint of heart for my car. 385446


Comments

I used these products for 2 separate trips about a year apart. First trip was about 7500 miles and the 2nd about 3500. No issues. Have not used the tent trailer for about a year. Have a trip coming up in about 1 month and dont expect any problems with these products.

Mark - 05/29/2018

39036

- C51515

by: Doug12/05/2018


I works great. Top quality! 588424



- C51120

by: Todd12/03/2018


This is my second one. It just works and is priced right. 588142



- C51120

by: Keith a11/19/2018


When i needed to replace my electric brake controller on my truck for pulling my trailers I first ordered from another dealer and when i got the unit and read the instructions there were about 3 items that i wasn't told about and sent it back ,so i kept searching for the controllers and came across e trailers , there were so many questions i had from my researching that when i called e trailers and talked with Preston he was so helpful in explaining the differances with controllers and i explained what i wanted and why he helped set me up with the right one .I then ordered the unit it was received faster than i expectided , it took me about 20 minutes to install the wiring harness and controller, I'm very happy with the customer service rep. Preston with help and time to explain and the choice i made thanks Preston and E trailers 584058



- C51515

by: Jim11/13/2018


Works well. 582452


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


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

  • Brake Controller Install in 2014 GMC Sierra
  • The install procedure will depend on if you have a 1500 or a 2500/3500 Series. If your Sierra is a 1500 model, you will need a brake controller wiring adapter harness, part # C51451. The 2500 and 3500 series would have the tow package wiring that sits above where the driver's left knee sits. If you click the video link I've provided, you can see a controller being installed in a 2014 GMC Sierra 1500. The FAQ link I provided shows how to install a controller in the 2500/3500 model. The
    view full answer...

  • Troubleshooting Brake Controller that Flashes When Connected to Trailer
  • It sounds like the problem is corrosion on the trailer 7-way brake output circuit which is causing the controller to only show an intermittent connection. Try cleaning off this pin on the 7-way with some fine grit sandpaper. Testing the brake controller is fairly easy. Sever the blue brake output wire near the brake controller leaving enough room to reconnect it and then apply the manual slide. Using a circuit tester like part # PTW2993, you should get output to the controller side of
    view full answer...

  • Troubleshooting Curt # C51120 Discovery Brake Controller Showing Flashing Decimal Point on Display
  • What you're describing sounds like it could either be an interruption in the trailer brake voltage output circuit, somewhere between the controller and the trailer brakes, or you could have a defective controller. Use a circuit tester with an incandescent bulb, like part # 40376 and use the probe to pierce the insulation of the blue output wire exiting the rear of the controller and ground the alligator clip. Apply the brake pedal. If the load provided by the tester causes the display
    view full answer...

  • Curt Brake Controller and Wiring Harness for a 2015 Ford F-150
  • For a Curt Discovery brake controller # C51120 you will need wiring harness # C51436 for your 2015 Ford F-150. I have linked video reviews for both parts for you.
    view full answer...

  • Curt Discovery Brake Controller Shows OL Error When Trailer is Connected
  • It is possible that it is a simple wiring issue that is causing the errors on your Curt Discovery brake controller # C51120. On your 2010 Chevy Silverado, there is a tow package wire bundle under the dash to wire in a brake controller. The tow package red goes to brake controller black. White goes to white, blue to blue, and the light blue or orange wire on the truck goes to the brake controller red wire. The OL indicates an overload and if all of the connections at the brake controller
    view full answer...

  • Brake Controller Installation Harness Recommendation for a 2015 Chevy Suburban
  • Yes, there is a port under the dash of your 2015 Chevy Suburban that will allow for a painless installation of a brake controller that won't require splicing. The harness to go along with the Curt Brake Controller part # C51120 that you referenced is the part # C51452. If you went with our most popular brake controller, the P2 part # 90885 you would only need the harness part # 3016. See the install video I attached.
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  • Troubleshooting Flashing 0.0 Error Message on Curt Discovery Brake Controller # C51120
  • The troubleshooting guide included in the instructions for the Curt Discovery Brake Controller # C51120 that you referenced does not include this particular display issue, a flashing 0.0, among the possible display messages. My technical contact at Curt has never seen this particular message displayed on a Discovery brake controller. He suggested that either the display is malfunctioning or the controller is bad. Since your brakes are not engaging when you press the pedal with the trailer
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  • Installing Curt Discovery Brake Controller # C51120 on 1988 Ford F150
  • To hardwire the # C51120 Curt Brake Controller, you can either cut off the existing plug on its wiring harness or use the universal pigtail, part # C51515. The universal pigtail would provide an easy way to quickly disconnect the brake controller, should it become necessary. You would then use our Brake Controller Installation Kit, part # ETBC7. If you do not already have a functional 4-pole trailer connector you would also need to install one using part # 118316. The install kit includes
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  • Curt Discovery Brake Control Flashing 0.0 Troubleshooting
  • The troubleshooting guide included in the instructions for the Curt Discovery Brake Controller # C51120 that you referenced does not include this particular display issue, a flashing 0.0, among the possible display messages. My technical contact at Curt has never seen this particular message displayed on a Discovery brake controller. He suggested that either the display is malfunctioning or the controller is bad. Since your brakes are not engaging when you press the pedal with the trailer
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  • Curt Discovery Brake Controller Is Only Showing A Dot When Engaging Manual Override
  • The Curt Discovery Trailer Brake Controller, # C51120, should show only the decimal point dot when the controller is activated and a trailer is not connected. If it shows the dot all the time, the red wire is connected to the wrong side of the stop light switch or the wrong switch completely like the cruise control. If you have only the decimal point when the trailer is connected, the usual cause is that the brake controller does not sense the trailer brakes. This could be due to corrosion
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  • Installing a Brake Controller in a 2009 Chevy Suburban
  • The 2009 Chevy Suburban does not have a port to plug in a brake controller which is the same as the trucks of the same year. But it does have the tow package wire bundle up under the dash, to the left of the steering column, held together with a white tag. Pull the wire bundle out to wire in a brake controller. With Curt brake controller # C51120 you will also need pigtail # C51515. Then you can make the following connections: Vehicle red/black wire to controller black wire for 12
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  • Troubleshooting Curt Discovery Trailer Brake Controller # C51120 Installed in 2002 Chevrolet Tahoe
  • Thank you for your recent purchases from etrailer. I would like to suggest some additional testing before you return the Curt Discovery Trailer Brake Controller # C51120. This will help isolate the problem and confirm whether the unit is indeed defective. The code OL indicates that the controller has sensed an overload condition. Disconnect the trailer from the Tahoe. Apply your grounded tester to the pins at the 5-o-clock and 7-o-clock positions on the Tahoe 7-way, as shown on the
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  • How to Find and Access the Brake Light Switch Wire on a 2015 Toyota Highlander for Brake Controller
  • If you check out the video I attached you will see how we installed a brake controller in a very similar 2014 Toyota Highlander as your 2015 model. We had to remove the lower dash panel (13:00 mark of the video), to make accessing the green wire possible. The kit used for the install in the video is the part # ETBC7.
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  • Curt Discovery Trailer Brake Controller # C51120 Displays Only a Red Dot After Installation
  • If your Curt Discovery Trailer Brake Controller # C51120 displays only a red dot when you do NOT have a trailer connected then this indicates that the controller's red (input signal) wire is connected to the wrong side of the brake light switch. This red wire should connect to the COLD side of the switch that has power only when you press the brake pedal. If your Discovery displays the red dot when you DO have a trailer connected then this usually indicates a problem in the trailer brake
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  • Wiring Curt Brake Controller # C51120 in 2002 GMC Sierra 1500
  • Based on your description of the problem with your Curt Discovery # C51120 Time Delayed Brake Controller one cause could be a mis-wired plug-and-play harness. Please refer to the photo provided which shows how the vehicle side of the harness should be wired. For reference I have also linked a help article concerning brake controller installations in GMC trucks. The connector should be pinned out with the four wires as shown in the provided photo. If the red wire is connected to a different
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  • Troubleshooting Flashing Display of the Curt Discovery Brake Controller part # C51120
  • The flashing O.L. message with the Curt Discovery Brake Controller part # C51120 when there is no trailer connected indicates that there is a short somewhere on the brake output circuit. I would check all the connections you made on the blue wire from the controller and then also check the trailer connector at the rear of the vehicle looking for any exposed wire or corrosion and fix as necessary. If it only flashes O.L. when the trailer is connected the problem is the same as above but
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  • How to Access Vehicle Brake Light Signal for Trailer Brake Controller Installation
  • If your 2005 Toyota Sequoia has a factory-installed 7-way trailer connector you can install the Curt Discovery trailer brake controller # C51120 using only the mating wiring adapter part # C51362. If it does not then the installation will be hardwired. You can gain access to the vehicle brake light signal, which is what triggers the Discovery controller to generate output voltage for the trailer brakes, either by tapping into brake light wiring or by installing a fuse tap in the brake
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  • Issues with Brakes Not Activating with Curt Discovery Brake Controller on 2015 Ram 1500
  • I spoke with my contact at Curt about the issues you and other customers have experienced with their Curt Discovery Brake Controllers # C51120 and newer model Ram trucks. The problem stems from a low voltage output on the stoplight wire on the truck. The Discovery requires 12 volts from the stop light wire in order to recognize the signal and activate the trailer brakes. Curt has found that the newer Ram trucks often have less than 12 volts at the stop light wire when the brake pedal
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  • 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
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  • 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
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  • 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
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  • 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
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  • 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
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  • 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
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  • 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
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  • 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
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  • 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
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  • 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
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  • 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
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Info for these parts were:

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

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