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  1. Trailer Brake Controller
  2. CURT
  3. Electric
  4. Electric over Hydraulic
  5. Proportional Controller
  6. Up to 4 Axles
Curt Spectrum Trailer Brake Controller - Dash Mounted Knob - 1 to 4 Axles - Proportional

Curt Spectrum Trailer Brake Controller - Dash Mounted Knob - 1 to 4 Axles - Proportional

Our Price: $239.95
You Save: $65.00
Trailer Brake Controller
Shipping Weight: 0.7 lbs
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Mount the control knob of this proportional brake controller on your dash for a from-the-factory look, and install the main unit out of sight behind the dash in any position or angle. Adhesive backing gives you the option of a drill-free install. Great Prices for the best trailer brake controller from CURT. Curt Spectrum Trailer Brake Controller - Dash Mounted Knob - 1 to 4 Axles - Proportional part number C51170 can be ordered online at or call 1-800-940-8924 for expert service.
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CURT Trailer Brake Controller

  • Electric
  • Electric over Hydraulic
  • Proportional Controller
  • Up to 4 Axles
  • CURT
  • Indicator Lights
  • Hidden
  • Dash-Mounted Knob
  • Automatic Leveling
  • Up to 360 Degrees

Mount the control knob of this proportional brake controller on your dash for a from-the-factory look, and install the main unit out of sight behind the dash in any position or angle. Adhesive backing gives you the option of a drill-free install.


  • Brake controller activates trailer brakes in proportion to your vehicle's braking action
    • Automatically adjusts trailer's braking based on deceleration of tow vehicle
  • Dash-mounted knob keeps your vehicle interior looking sleek while giving you easy access to the brake controller
    • Lets you adjust braking output and sensitivity with the turn of a dial
    • Gives you a manual override at your fingertips
    • Offers simple diagnostics with colored LED indicators
    • Mounts to dash with included screw, or you can use the included adhesive pads for a drill-free installation
  • Main unit installs out of sight behind the dash in any position, direction, and angle
    • No more banging your knee on a bulky controller
    • No interference with airbags or other vehicle accessories
    • Custom plug-in adapter (sold separately) available for select vehicles to reduce installation time
  • Compatible with ABS brakes, cruise control, low-voltage wiring, multiplex wiring, and PWM systems
  • Assembled in the USA


  • Application: trailers with up to 4 axles (8 brake assemblies)
    • Compatible with electric or electric-over-hydraulic trailer brakes
  • Main unit dimensions: 3" long x 3-1/2" wide x 7/8" tall
  • Control knob dimensions:
    • Extension: 1-1/2"
    • Diameter: 1-3/4"
  • Cable length: 4'
  • Limited lifetime warranty

The Curt Spectrum brake controller is all about easy installation and keeping the interior of your vehicle clutter-free. With the main unit mounted out of sight behind the dash, all you need is the control knob to operate the settings on the brake controller. You won't be banging your knee on a bulky controller or ruining the sleek look of your interior.

Curt Spectrum Operation

The Spectrum's dash-mounted knob puts control of your trailer's brakes at your fingertips. In addition to giving you fast, simple power adjustment and a manual override, it has colored LED indicators to offer diagnostics and let you know what the brake controller is doing at a glance.

Curt Spectrum Dash-Mounted Knob

The Spectrum has a full menu available in the control knob so you can get your settings just right. To switch between modes, press the control button in the center of the knob. Each mode has its own distinct LED display with several different colors and patterns to eliminate any guesswork as you cycle through.

Curt Spectrum LED diagnostics

Output: Braking output is 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 set the braking output as high as you can without locking up the brakes. Adjust the braking output by applying your brakes and turning the knob clockwise. Once you've set up the brake controller the first time, you shouldn't need to adjust the settings until the trailer load changes, you switch trailers, or road conditions change.

Sensitivity: This controls the aggressiveness of your trailer's braking, meaning how quickly the brakes reach the set output level. This is a great adjustment to make when you're towing a heavy load and the trailer will need more umph to bring it to a stop so it doesn't push your 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.

Manual Override: The Curt Spectrum keeps the manual override within easy reach. The manual override functions as time-based for a slow reduction in trailer braking, great for stopping sway or controlling your trailer's momentum in an emergency. To engage the manual override, just press and hold the button on the control knob. 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.

Curt Spectrum review

Simple, Out-of-the-Way Installation

Unlike many proportional controllers on the market, the Curt Spectrum has almost no mounting restrictions. It comes in 2 pieces: the main unit and the control knob. Because the only part that you need to be able to access is the control knob, the main unit can be mounted out of sight and out of the way. You don't have to worry about dinging your knee on a bulky brake controller or interfering with your vehicle's lower airbags.

Curt Spectrum Dash Knob

The dash-mounted control knob can be installed in any convenient spot that's easy for you to see and reach. This can be a blank switch panel, an open spot on your center console, or wherever there's space on your dashboard. Because the knob sits flush against the dash, you don't have to worry about clearance behind the dash when you're installing it either. You can either use the included screw to mount the knob or use the adhesive pad for a drill-free installation.

Curt Spectrum Install

Once you've decided where you want to put the control knob, you'll need to find a good place to install the main unit. Your only restriction is the 4' plug-in cable that has to be able to reach between the main unit and the control knob. Thanks to the 3-axis accelerometer, the main unit can be positioned at any angle or position. No matter how you install it, the unit will sense the direction of travel and its orientation.

If your vehicle already has a plug-in brake controller wiring harness, just connect the main control module 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, a 30-amp circuit breaker (sold separately) may be required for installation.

Proportional Braking

What is proportional Braking

The Curt Spectrum 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 Spectrum uses an internal 3-axis accelerometer to sense 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 ensure that your trailer slows at the same rate. The result is uniform braking across your towing setup. No push-pull action - just smooth, proportional braking every time.

51170 Curt Spectrum Trailer Brake Controller - Dash Mounted Knob - Proportional - 1 to 4 Axles

Item # C51170

Installation Details C51170 Installation instructions

California residents: click here

Customer Satisfaction Score:

Customer Reviews

Curt Spectrum Trailer Brake Controller - Dash Mounted Knob - 1 to 4 Axles - Proportional - C51170

Average Customer Rating:  4.6 out of 5 stars   (300 Customer Reviews)

Mount the control knob of this proportional brake controller on your dash for a from-the-factory look, and install the main unit out of sight behind the dash in any position or angle. Adhesive backing gives you the option of a drill-free install.


This is my 2nd purchase of Curt spectrum brake control. When installing the first device, I accidentally broke one of the 6 wires (wiring the plug connector to the led display knob). I tried to fix it but it didn't work for long. That's why I had to order a 2nd device. For the installation of the 2nd, I was very meticulous because the 6 wires are very fragile. I succeeded by taking my time and everything works very well. The Curt company would do well to manufacture this device more robustly. For looks, it's ok in my 2019 Honda Passport.

Ceci est mon 2e achat de Curt spectrum brake control. Lors de l'installation du premier appareil, j'ai par accident brisé un des 6 fils (wiring the plug connector to the led display knob). J'ai tenté de le réparer mais il n'a pas fonctionné longtemps. C'est pourquoi j'ai dû commander un 2e appareil. Pour la pose du 2e, j'ai été très minutieux car les 6 fils sont très fragiles. J'ai réussi en prenant mon temps et le tout fonctionne très bien. La compagnie Curt aurait intérêt à fabriquer cet appareil de façon plus robuste. Pour l'apparence ,c'est ok dans mon Honda Passport 2019.

Henri G.


Après un an dusage, je trouve ce produit difficile à ajuster selon le poids chargé dans la remorque. Le processus est compliqué et je dois me référer au livre dinstruction. Pas pratique.

Etrailer Expert

Mike L.


@HenriG The Curt # C51170 Spectrum Brake Controller isn't the most user friendly model out there, but the procedure to adjust the output and sensitivity is not unlike many other controllers. This procedure is outlined on page 12 of the instructions we've linked for you. If you have specific questions, let us know and we'd be happy to help!


Works great. (Better than any standard brake controller ive used in the past) Easy plug and play operation
I chose to not drill into my dash rather just ran the cord up by the steering column


I ordered the Curt Spectrum trailer brake controller after much research. I was looking for a brake controller with a clean looking install (I didn't want an underdash mount) for my 2020 Chevy Blazer. My Blazer had the tow package from the factory which made the install fairly easy. All the wiring for a brake controller is there behind the driver side kick panels. The Curt Spectrum once installed and adjusted works flawlessly. Just follow the enclosed instructions to adjust the Spectrum for the load you are hauling. I could not be any more pleased with the way this product works and highly recommend the Curt Spectrum brake for your auxiliary braking needs.


Looks great and works well. Only gripe I have is that I don't use it enough to remember what all it does at the different light colors. More of an issue for me, not the product. Matches my 2020 Ford Explorer interior and other dials. Looks factory.



Its doing fine, i now have a dedicated tow vehicle so I rarely use this vehicle. Its been so long since I used it, I totally forget how to change settings if i needed to Would have to Google it Beleive I lost my cheat sheet card also. Still looks great and Im glad I did go with this model.

Etrailer Expert

Mike L.


@Charles We're glad to hear it was working well for you during the time you used the vehicle. I've linked to the owner's manual/operating instructions for you!


This brake controller works perfectly for my 2014 Audi Q7! The instructions were easy to follow thereby making the installation a straightforward process. The hardest part was deciding where to install the dial. The dial has a solid and deliberate feel when turning and numerous options for fine tuning.


Great break controller! I stalled it in a 2020 Hyundai Palisade. Followed a video of the installation which walked me through most of the steps and had to improvise a few more. But all in all it's a great looking and great working controller. It's appearance makes it look like it is just another part of the car.


I knew I wanted to have something like this due to the look, function and size. The package was small. Installed pretty easily with minimal headaches. I just watched the videos online to see how others did it and how to steer away from making damaging mistakes. The booklet was also very helpful to make everything fit as it should while putting the steps in order.

As I pull a trailer 90% of the time, I wanted something to have the easy manipulation for the brakes yet have an aesthetically pleasing look. This does just that. Brakes on one setting. Adjustable on two other settings. Very quick.

Although I did have to play with the settings to make sure it wasn’t jerking me in my seat every time I pushed the brake pedal, after a day, smooth sailing.

I do recommend you seriously think about this brake controller. Ease of install and the application is perfect.



Wonderful! It has been a great tool!


2019 Honda Ridgeline RTL AWD—
The Curt
Spectrum C51170 controller and harness C51392 was exactly as I had read it would be! All connections hooked up as described and all connectors fit! The knob works as described but I have yet to hook up trailer to get response from the accelerometer! I’m sure the quality shown it will work fine! Only problem I had was access under the dash. Thanks Bill and etrailer! Pictures attached!



I really haven’t used it much after install except to test with empty car trailer. It worked well. Three or four people I have showed it to have been impressed! Thanks


This is our second purchase from etrailer. Their delivery was very prompt and the items were exactly what we needed. The Trailer Brake Controller was simple to install and works absolutely great!


The compact remote control knob feature is a good plus for this product. Installation was really easy with the interface harness on the second generation Tacoma. I haven't had a lot of towing time with it but can offer the following insight.

The control lights are easy to use and adjust. They appear to be dimmed with pulse width modulation so if your eyes are sensitive to it you might look at one before you buy. Hopefully they can go PWM-free at some point. The "white" color lamps appear as a mix of flashing red green and blue. Indicator lights are plenty bright in the daytime but the lowest dim setting is too bright. Perhaps this was done to minimize the PWM flashing at the dim setting. I had to locate the knob in the shadow of the steering wheel to keep the light out of my eyes at night.

I've also noticed a single artifact light on many occasions after brake release (see pictures). So far the lamp color has been red, green, and blue however I have not yet seen a "white" one. One of these lights often come up in random positions on the dial. This lamp will continue to burn after I get out of the truck, and won't go out until I press the brake pedal again or push the knob. If I push the knob the output or sensitivity adjustment mode arc comes up briefly and it goes out after a bit (as it's supposed to). OEM brake control harness and grounding were sound with typical resistances around a milliohm or less.

This controller is a considerable parasitic draw on the battery even with the lamps out and the ignition switch off. This could be an issue particularly if an artifact light is not noticed and the truck sits for more than a week(which mine sometimes does). A depleted battery made me look into this with a Fluke ammeter. You might consider pulling the fuse if the truck will sit or hook up a trickle charger.

I tried to make contact with the manufacturer to see if they had any free convection requirements for air flow around the main module (air cooling at 100% duty cycle), and to understand what is going on with the controller and if there was something that could be done to fix the lights, perhaps a firmware update or something but never got any replies. The folks at etrailer maintained good communication and were excellent to work with but I don't feel the manufacturer is willing to support their product. This could be an excellent product if they can address these issues.


No modifications required. I didn’t want to drill any holes in the new truck dash. This easily mounts in the clip provided with a small cable coming from under the dash.

by: 10/10/2023

It was pretty easy to install but took about an hour due to everything being under the dash at an awkward angle. The supplied sticky tape Velcro did not hold the brake control in place under the dash so I used zip ties. I ended up using heavy Velcro from a hardware store to attach the knob to my 2018 Chevy 1500 truck dash since I did not want to drill a hole. The mounting Velcro was not strong enough to stay in place on dash The lights are a little hard to activate to cycle through to adjust the settings, but it brakes good. I pull a 7x14 cargo trailer. The support was good when I had some questions.


I really like the finished look of this controller after it is installed (see before and after pictures attached)! I also like being able to finely tune it to my need using the power output and sensitivity adjustments. I do have a minor issue with connecting a trailer to my 2020 Jeep Gladiator, though. If I connect the trailer while the engine is running, the electronic stability control and engine start/stop services on the truck disable themselves. Turning the ignition all the way off an on again resolves the issue, as does having the engine off when I connect the trailer. Aside from that minor inconvenience, this controller works admirably and I would buy it for other vehicles.

Installing was simple with the adapter for factory wiring. The most difficult part was identifying the location for the knob and taking the dash apart to install it properly. The finished appearance is clean and the only visible aspect of the entire system is the control knob.

With the sensitivity and power controls on mid-level, the trailer tires were skidding on quick stops. Tuning the settings to have less sensitivity and less power quickly corrected that issue. I am quite happy with this controller!


This controller is a really good concept but kind of challenging to get dialed in correctly for each load. When braking in a straight line it performs as expected but when braking while turning or on bumpy roads it often times surges the brakes making them lock up.

I have been using this product for 1 year and am now figuring out ways to work around the surges. Best way I've found is to keep the sensitivity on high and only adjust the power setting.

The 4 star rating on this product is for how small and sleek the adjustment knob is vs standard brake controllers installed In the dash it feels almost factory.
Install took about 5 -10 minutes

Overall I am happy with this purchace
it's just not quite as user friendly as I'd hoped.


Everything ordered arrived expeditiously. Will be installing the electricals along with the 'etrailer' hitch/towbar during early March and will let you know the outcome with photos at that time. So far, extremely satisfied with your superb website, punctual treat of my order, and the speed and efficiency in which it was delivered.

Reginald B.


Excellent. Could not be happier with your products.


Worked well in my Infiniti 2017 QX60 but install was not that easy.
First unlike other etrailer products, I could not find an install video for my car. For other Infiniti owners out there, the brake controller connector is located along the wiring harness connected to the OBD connector. You cannot see it as it is lightly taped up, you just need to feel for it and pull it down. Secondly it is *capped*. The cap looks very much like the plug itself so don't be confused. Remove the cap and you can install. Make sure you get the right Curt adapter for your car.
Secondly the install requires the user to insert the crimped controller wires into a connector for control module. There are videos on how to do this however it did not go as easy as shown. Maybe I had a defective part, but there is clearly only one way to insert the wires but I had to insert with significant force to get them in all the way.
Once installed the unit worked fine with my 3,800lb RV trailer. A few nits: Occasionally the control knob will leave as one of its lights on after the car is turned off. Its happens occasionally and can be reset by pushing the brakes again but seems like a bug? Also the knob will *always* light up if you press the brakes even if you do not have a trailer attached. There is no way to turn this feature off and can be kinda annoying if you do not tow that much.
Overall, works as advertised and like how it can be tucked away, but wish the install was better explained for my vehicle and didn't bother if there was no trailer attached.


I chose this controller as the main module fits out of sight and does not have to be aligned or leveled. I attached it to the parking brake bracket on our Pilot. The LED rotary control knob fits nicely on the dash and after inserting the cable through a small hole in the dash, connecting the plug was simple with the pins that were attached to the cable. What was confusing was the instructions do not mention there are two base plates - one for adhesive mounting to the dash and the other for drill mounting (what I did). I tried to snap the rotary knob into the base plate I mounted, but it would not fit. I found out that the rotary knob actually comes with the adhesive mount already attached and you have to use a small screw driver to pry it off so you can use the other base plate. Luckily Curt has an installation video on their web site that showed removing the adhesive plate. I generally do not start taking apart precision gear without some hint of what should be done. Curt also has a custom cable that plugs into this unit and the port on my Pilot.

When I get our trailer I will be able to review the performance of this controller.


Great product. Easy install in under 45 minutes to integrate into factory OEM harness. 2017 Land Ro er Discovery Sport with factory trailer tow package will be plug and play with this controller, and Curt custom wiring Adapter C51322. The factory brake controller integration harness is directly behind the OBDII connector on the driver’s side. Everything else is in place. Note: your factory OEM tow connection MUST be dealer activated in your vehicle. Without that activation, the body controller will not pass power to the brake module.

There is ample space inside the dash on the left side, behind the left knee bolster to place the control module in a securable and protected location. This requires only 3 easy to remove panels, and 2 screws to reach. If oriented properly, the DIP switches are accessible in future by removing the dash side panel (zero tools required).

There are multiple locations for the control knob. The look and style of the control knob fits perfectly with the design of the interior. Love the ability to use a drill or no-drill installation method.

We haul our Forrest River travel trailer with this vehicle and previously used a time-based controller that “fought” with the vehicle’s integrated trailer stability control and anti-sway detection. This controller has solved this issue and gives complete control while integrating seamlessly with factory stability systems.

Even with the output or sensitivity at high levels, this system still works perfectly with the vehicle trailer stability control. This was a vast improvement over our old time-based controller.

Great function and fantastic look. For a non-OEM product, this truly does have an OEM look, function and ease of installation. Curt did a great job with this.

My only nit is that both Curt and etrailer do not recognize the factory connection adapter harness as an option on the Discovery Sport. TIP: If you select the Land Rover Evoque (shares the same platform as the Discovery Sport) the options become correct for your Discovery Sport as far as factory adapter harnesses.

Super fast delivery. Would be better if drop-ship items included an actual tracking number instead of only the user login web based tracking option. The web based tracking required logging in to monitor for delivery times. Some kind of automated text or email shipping updates for drop-ship items would make a great buying experience into a fantastic one.


I bought this because I wanted a factory look. This was easy to install and looks great. You have to learn what the different colors and settings do but it’s not that difficult. Overall I am very happy with this brake controller.



I have thousands of miles on the trailer now. The brake controller has worked flawlessly. I have towed cars, ATVs and loads of lumber just set the controller for the load and it does the rest. Excellent product.


I've had the brake controller in use
for over a year in my 2012 Nissan Frontier. The install was easy and took about an hour. My truck is a 2WD model so I mounted the controller in the plug that is used to select between 2WD and 4WD on vehicles equipped with 4WD. So the install look like factory.


Everything installed great. The overall look of the knob if excellent. The direct plug in to the Ford OEM brake plug is excellent. Have not towed anything yet.
P.S.: The screw-in base with well nut - which is the more secure option (not the adhesive option) for the knob... the screw prevents the knob from seating perfectly square... the base bottoms out just slightly on the screw. It does click in, the screw is a very flat pan head... perhaps there is a flatter screw or the there is more space in the knob undercarriage, but another 1/16" of space probably gets it just right. If the seating gets weird (i.e in cold weather may shrink cause plastic to contract slightly and lose seating, I can always use a machine screw and nut washer to clean it up... plenty of space to access the fastener from mounting place. 2008 Ford Expedition.


Honda Ridgeline 2019 Install
Plan to
tow an RPOD 195 Travel Trailer as soon as I pick it up
Simple Installation
Didn't need to remove dash to install, as free space behind this location.
Knob on lower left of Dash.
Module Tie Wrapped to the Parking Brake Bracket under the Dash.
Used the C51392 Wiring adapter to connect the Brake Controller to the Truck.

Pictures of Dash Install only.
Haven't functionally tested yet as I am waiting on Delivery of the Trailer.

by: - Awesome! Excellent customer service. Have dealt with them many times, Knowledgeable, Friendly and Helpful, great products at competitive prices. Highly Recommend.
Curt Spectrum - Neat and clean, straight forward installation. Just make sure the wires to the plug connector are fully seated to the plug connector. Custom wire adapter makes installation plug and play. Picture is 2017 Silverado 1500.


The installation went very quickly and the end result was very satisfying. The location of the switch on the dashboard makes it hard to spot as an aftermarket add on. The whole installation took 1 hour start to finish. I can't wait to tow a trailer so that I can get the Cuurt Spectrum Brake Controller calibrated and dialed in. Thanks etrailer! Thank Curt!


Decided I wanted a high quality brake controller without the clunky box on the dash and this seemed like the best out there. Super easy install. I bought the extra cable for my Silverado and it all plugged in perfectly. I saw somebody complain about tiny connectors. Don't listen to them. This thing is excellent and the quality is clearly top tier. The set up was a breeze and on our first trip out I got it dialed in with no problems. Works better than my previous controller by far.

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