Towing a Trailer with Electric Brakes with a Semi Tractor with Air Brakes
Question:
I see the air to electric brake controller. Do you have any products for converting the light control wiring from my tractor to my goose neck. I tried making my own convertion it works but interferes with the RF brake controller operation. Thanks towing an electric brake trailer with a semi tractor.
asked by: Ryan D
Expert Reply:
To tow your trailer that uses an RV style 7-way blade style connector with your semi that has a 7-pin connector, you need to construct an adapter that will also combine the brake signal into the right and left directional signal pins.
This can be done by using a female 7-pin socket # PK11720 to accept the plug from the semi, a tail light converter # 119178 and a female 7-way RV blade-style socket # PK12-707E. The converter would be wired in between both sockets to combine the brake light signal onto the right and left turn circuits for the trailer. See the diagram I included showing how to wire this setup.
The Hayes air utility brake control # HA100400C you referenced will work as this controller taps into the semi air brake line and sends an electrical signal back to the trailer brakes when activated.
What I recommend and is easier to install would be to get a Tekonsha Prodigy P2 brake controller, part # 90885. Electric brake controllers do not tap into the vehicle braking system at all. They only need an input signal that tells it you are stepping on the brake pedal then it sends power back to the trailer brakes.
On the brake controller, the white wire needs to be grounded to the battery, the black wire connects to the positive battery terminal via a 30 amp circuit breaker, # PK54530, the blue wire goes out to the trailer connector and the red wire is input from the brake switch.
I included a few helpful articles and video review for you to look at.
Products Referenced in This Question
Upgraded Circuit Protected Tail Light Converter with 4-Pole Flat Trailer Connector
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Converter
- 1-1/2 Feet Long
- Universal Fit
- 4 Flat
- Tekonsha
more information >
Tekonsha Prodigy P2 Trailer Brake Controller - 1 to 4 Axles - Proportional
- Trailer Brake Controller
- Proportional Controller
- Electric
- Electric over Hydraulic
- Automatic Leveling
- Under-Dash Box
- Dash Mount
- Up to 4 Axles
- LED Display
- Up to 360 Degrees
- Tekonsha
more information >
Pollak Heavy-Duty, 7-Pole, Round Pin Trailer Wiring Socket - Vehicle End
- Trailer Wiring
- Trailer Connectors
- Vehicle End Connector
- Plug Only
- 7 Round - Round
- Pollak
more information >
Pollak Black Plastic, 7-Pole, RV Blade-Style Trailer Socket - Vehicle End
- Trailer Wiring
- Trailer Connectors
- Vehicle End Connector
- Plug Only
- 7 Round - Blade
- Pollak
more information >
Pollak Circuit Breaker - Cycling/Automatic Reset - 30 Amp - Straight Mount Bracket
- Accessories and Parts
- Wiring
- Circuit Breaker
- 30 Amp
- Pollak
more information >
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on Trailer Brake Controller
Mark T.
3/17/2025
I need something to make my electric trailer brakes to work from an Semi air brake system. right now they lock up when I use an adapter for the 7 pin round connector on the truck to the 7 way flat connector on the trailer rv plug-in . . any ideas ? any list of items needed ? need help and fast