Tekonsha Trailer Brake Controller
- TK78HR
- Electric
- Electric over Hydraulic
- Proportional Controller
- Up to 4 Axles
- Tekonsha
- Under-Dash
- Plug-In
- Under-Dash Box
- Single Trailer Only
- LED Display
The Tekonsha P2 is a classic brake controller you know you can rely on. It's easy to install, and with the custom harness, it's plug-and-play.
Features:
- Proportional - Smooth, safe, and good for your brakes long-term
- Fast installation - Mount the bracket to the dash and then attach the unit to the bracket
- Plug-and-play - Custom harness included
- Simple controls - Thumbwheel for gain, button for boost, and manual override lever
- Easy-to-read screen - Large, simple, and dims automatically
- Safe - Built-in safeguards protect vehicle, trailer, and controller
- Quick disconnect - Easy to unplug and remove the controller when you don't need it
- Automatic leveling - Must be parallel with direction of travel and horizontally level
Specs:
- Application: trailers with up to 4 axles (8 brake assemblies)
- Compatible with electric or electric-over-hydraulic trailer brakes
- Dimensions: 5-1/8" long x 3-1/8" wide x 2" tall
- Mounting: 360 degrees vertically
- Warranty:
- Limited lifetime on brake controller
- Limited 1-year on wiring harness
Gain Adjustment
![Tekonsha Prodigy P2 gain]()
Gain 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 go as high as you can without the trailer brakes locking up.
You can adjust the gain by turning the thumbwheel on the front of the controller.
Power Boost for Heavy-Duty Towing
The boost setting controls the aggressiveness of your trailer's braking, meaning how quickly the brakes reach the maximum braking level. If your vehicle takes too long to come to a stop, increase the setting. If it stops too abruptly, decrease the setting.
Depending on the level of boost, your trailer brakes can start at either 13 percent or 25 percent of the set gain. So instead of starting at 0, the brakes will start at 25 percent and get to 100 percent sooner. This keeps the trailer from pushing your tow vehicle forward.
Boost Levels:
| Approximate Gross Trailer Weight | Boost Level | Increase in Initial Power Output |
| Less than tow vehicle GVW | B1 | 13% |
| Equal to tow vehicle GVW | B1 or B2 | 13% or 25% |
| Up to 25% more than tow vehicle GVW | B2 or B3* | 25% |
| Up to 40% more than tow vehicle GVW | B3* | 25% |
*Both B2 and B3 offer a 25-percent boost in initial power. But the braking curve for B3 is more aggressive than that of B2. This means that, even though you will start out with the same intensity when using these boost levels, you will get an overall more aggressive braking experience with the higher level. So if you use B3, you will reach maximum braking sooner than if you use B2.
Manual Override
To engage the manual override, twist the rotary-style lever from right to left. This will activate the trailer's brakes and brake lights independently of your vehicle, great for stopping sway or controlling your trailer's momentum in an emergency.
Safety Features
The Prodigy P2 offers key safety features to prevent damage to your towing setup:
- Integrated reverse battery protection shields the brake controller and your trailer's breakaway system from shorts.
- When the P2 is not in use, it draws only 3.6 milliamps to minimize the drain on your vehicle's battery.
- Any time your vehicle and trailer are at a standstill with the brakes applied for more than 5 seconds, the hold feature will kick on and reduce power to just 25 percent. This will keep your trailer in place without your brakes overheating.
The Prodigy P2 also runs continuous diagnostics to check for problems as they come up, including:
- Open ground
- Overload
- Output short
- Power loss
- No trailer connection
Installing the Tekonsha P2
Installing the P2 is incredibly simple. You'll mount the bracket to your dashboard then mount the unit to the bracket. Plug the custom harness into your vehicle and into the unit. Done!
Keep in mind that the P2 must be horizontally level and parallel with the direction of travel to work correctly.
![Prodigy P2 correct mounting]()
With a replacement wiring harness (sold separately) and replacement bracket (P7685 - sold separately), you can even transfer the Prodigy P2 to another vehicle.
Note: If you don't already have a 7-way plug at the back of your vehicle, take a look at our exclusive 7- and 4-way brake controller installation kit (ETBC7 - sold separately).
What is Proportional Braking?
![What is proportional braking]()
Proportional braking means that your trailer brakes mimic your tow vehicle's brakes. If you slam on the brakes, 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 Prodigy P2 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.
90885 Tekonsha Prodigy P-2 Proportional Brake Controller - 1 to 4 Axles
Replaces Tekonsha 90185
302400 Tekonsha Brake Control Wiring Adapter with 2 Plugs
Replaces Tekonsha 3024-P
Installation Details 
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