Another aspect of towing a trailer is the brake controller. An HDT does not lend itself well to the normal pendulem/inertia type controllers due to its size. There were a couple companies making good controllers for this niche market but they have come and gone. Hayes makes a controller that interfaces with the air brake system, but a physical connection to the air brake line must be made. Tuscon RV makes a product called DirecLink that is becoming the standard controller for HDTs. It connects to the OBD (on board diagnostic) port to obtain brake pressure. I purchased one with a discount on Black Friday.
The DirecLink is not specific to HDTs. Any vehicle with an OBD2 port can use it. In fact, an HD Truck Module adapter harness is required to interface with the odd (9-pin round) HDT OBD port.
The contents of the box. The cable in the box is the one a car or truck would use and fits a standard OBD2 port.
An overview of the system. I like it that all the cable parts screw together.
My introduction to the DirecLink system was a video of Gregg Shields installing one. He stuck all the electronics and cables in the area above the OBD port. There are a lot of wiring and air lines there and it seemed like it would be very crowded, so I decided to put the controller under the dash. I had it apart doing other things. There was more than enough wiring and cable to reach.
I hooked everything up to do a test before I actually mounted it. I turned the key on and...nothing. Hmmmm. I checked and it was getting power. When it doubt, read the instructions.
The solution was simple. In addition to applying power you have to hit the brakes to activate the system. Everything worked fine.
I was unsure where I was going to put the control head. I tested the system with a telephone cable in case I wanted to mount it far away. It worked fine.
I decided to put the control head to the right of the steering wheel. The coiled cord reached without issue.
The OBD connector in place. It doesn't interfere with the steering wheel adjustment lever.