Trailer Brake Controllers
Proportional vs Time-Delay Brake Controllers
A time-delay controller does the same thing whether you are easing to a stop or standing on the pedal. That is the problem.
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Short answer
A proportional controller uses an accelerometer to match trailer braking to the tow vehicle's actual deceleration. A time-delay controller ramps to a preset output over a fixed time, regardless of how hard you are braking.
What each one does when you press the pedal
Time-delay
The brake light signal starts a timer. Output ramps from zero up to a level you set, over a period you set. That is all the information it has - it does not know the severity of the stop. Set the ramp aggressively and gentle stops feel like the trailer is grabbing. Set it gently and an emergency stop has the trailer arriving late.
Proportional
An accelerometer measures the vehicle's deceleration and the controller outputs in proportion to it, scaled by the gain you set. Ease off at a red light and the trailer brakes gently. Stand on the pedal and the trailer gets full output immediately. The rig behaves as one vehicle.
| Situation | Time-delay | Proportional |
|---|---|---|
| Gentle stop at a light | Fixed ramp - can feel grabby | Light, matched braking |
| Emergency stop | Ramp still runs - trailer is late | Full output immediately |
| Long downhill | Fixed output each application | Matched to actual deceleration |
| Mounting requirement | None - no sensing | Modern units self-level |
| Setup | Output level and delay | Gain only |
Why mounting angle used to matter
Early proportional controllers used a pendulum and had to be mounted level within a narrow range or they misread deceleration. Current units use multi-axis sensing - CURT publishes tri-axis inertia for both Echo and Spectrum, with mounting at various angles and automatic level adjustment - so the old objection to proportional controllers has been engineered away.
Quick picks
Tap any row to jump to the full write-up. How these are chosen - and what we do and do not claim to know - is published in full on our research methodology page.
| # | Product | Best for | Our read | Price |
|---|---|---|---|---|
| 1 |  Tekonsha Primus IQ Trailer Brake Controller Proportional, affordable | One truck, one trailer | Entry-level proportional done simply | Check price on Amazon #ad Affiliate link - we publish no price; Amazon shows the current one |
| 2 |  CURT Spectrum Integrated Proportional Brake Controller Proportional, more axles | Multi-axle trailers | Tri-axis sensing, up to 8 with wiring | Check price on Amazon #ad Affiliate link - we publish no price; Amazon shows the current one |
| 3 |  CURT Echo Mobile Trailer Brake Controller Proportional, no wiring | Rental trucks and borrowed tow vehicles | Tri-axis inertia in a plug-in body | Check price on Amazon #ad Affiliate link - we publish no price; Amazon shows the current one |
1. Proportional, affordable
Tekonsha Primus IQ Trailer Brake Controller
Tekonsha · Best for one truck, one trailer
Proportional braking without the memory, the boost profiles or the big display. For one truck and one trailer, that subtraction costs you almost nothing in how the rig actually stops, which is why it stays the default recommendation for a first controller.
We have not sourced a full specification table for this model from the manufacturer’s own site at a stable address. Rather than repeat figures we cannot cite, the assessment above is limited to what the design and the maker’s published description genuinely establish.
What works
- Proportional response at a far lower price than a flagship controller
- Small enough to mount where a larger unit will not fit
- Mounts at a range of angles without needing to be level
What does not
- No per-trailer memory, so a second trailer means re-setting gain each time
- Display tells you much less when something is wrong
Skip it if
Not the one if you swap between a light utility trailer and a heavy camper - without stored settings you will eventually drive off on the wrong gain.
#ad Affiliate link - we publish no price; Amazon shows the current one
2. Proportional, more axles
CURT Spectrum Integrated Proportional Brake Controller
CURT · Best for multi-axle trailers
A hardwired proportional controller with tri-axis sensing, a tri-color LED readout and a wide axle range - up to four braked axles, or eight with the right wiring. Mounts at essentially any angle, which solves the main problem of fitting a controller to a modern dash.
Published specifications
What works
- Mounting angle is a non-issue, which widens the list of places it will fit
- Covers heavier multi-axle trailers that a basic controller will not
- LED color tells you the state at a glance without reading a number
What does not
- An LED is a far coarser diagnostic than a text display
- Still a hardwiring job with a vehicle-specific harness
Skip it if
Skip it if you want to read exact output voltage while you tow - the color band is deliberately simpler than that.
#ad Affiliate link - we publish no price; Amazon shows the current one
Raw specifications: CURT’s own page. We earn nothing on that link.
3. Proportional, no wiring
CURT Echo Mobile Trailer Brake Controller
CURT · Best for rental trucks and borrowed tow vehicles
Plugs into the 7-way instead of being wired under the dash, and runs from a phone app over Bluetooth. Tri-axis inertia sensing means it does not care how it sits. The trade is that your brake interface is a phone, which is a real objection and not a small one.
Published specifications
What works
- No wiring, no drilling, and it moves between vehicles in seconds
- Tri-axis sensing removes the level-mounting requirement entirely
- Ideal when the tow vehicle is not yours to modify
What does not
- The manual override lives in a phone app, which is the wrong place for it in an emergency
- Rated for one and two-axle trailers only
Skip it if
Not for a triple-axle trailer, and not for anyone who wants a physical lever they can hit without looking.
#ad Affiliate link - we publish no price; Amazon shows the current one
Raw specifications: CURT’s own page. We earn nothing on that link.
Key takeaways
- Time-delay ignores how hard you are braking; proportional measures it.
- The difference is largest in exactly the stop where it matters most.
- Modern proportional units self-level, removing the old mounting objection.
- Both need the gain set properly - neither is set-and-forget.
How we sourced this
Every figure on this page came from one of the following, each fetched while the page was written. Where a manufacturer or regulator does not publish a number, we say so rather than estimate it.
Common questions
- Is time-delay ever better?
- In a very few situations - some drivers prefer the predictability on loose surfaces, where proportional sensing can read the vehicle's motion unhelpfully. That is also solved by controllers offering a user-controlled mode.
- Do I need to mount a proportional controller level?
- Not on current units with multi-axis sensing, which publish mounting at various angles. Older pendulum designs did require it.
- Can I tell which type I have?
- The manual, or the model name. If setup involves setting a delay or ramp time as well as an output level, it is time-delay. If the only adjustment is gain, it is proportional.
More in Trailer Brake Controllers
If the trailer has electric brakes, something has to tell them how hard to work. That something is a controller, and how you set it decides how the rig stops.
Read next
Best brake controller
Best Brake Controllers
Hardwired and plug-in proportional controllers compared on published specifications and how each behaves when something goes wrong.
How to
Adjusting Brake Gain
The empirical gain procedure, how to read under- and over-braking, and the loads that make a reset necessary.
Head to head
Wireless vs Hardwired
Plug-in Bluetooth controllers against traditional under-dash units, on installation, override access and axle ratings.
Guide
Do I Need a Brake Controller?
A decision path covering unbraked, surge-brake and electric-brake trailers, plus what to check on your tow vehicle first.
Found something out of date, or a figure you can source better than we did? Corrections get read first. How we research explains how these pages are put together, and contact is one click away.