During winter in northern Maine, snow that accumulates on the tops of trailers begins to melt when the vehicles are brought into the shop for inspection. One fleet burned through multiple market-leading trailer diagnostic tools as a result of that snowmelt runoff, said Bruce Theriault, creator of Trailer Dr.
“Then they tried mine, and they ended up putting it in the worst place of all—the wash bay,” Theriault said. “It survived.”
Trailer Dr. is a new one-person electrical and air brake trailer diagnostic tool designed to help technicians verify trailer lighting, air supply and brake activation from the rear of the trailer in the shop, the yard or even roadside.
The portable, waterproof tool delivers 30 amps of output in a 15.2-pound unit and plugs directly into a trailer’s seven-way connector. Using a remote, a single technician can activate electrical functions, supply air, and trigger brakes. This eliminates the need for a second person in the cab, reducing missed faults, repeat inspections, and downtime.
Theriault said to think of the remote as a truck in the palm of your hand.
Trailer Dr. tests brake, turn, running and marker lights; electrical connections and wiring faults; air leaks; air supply to the trailer; brake activation and air brake response. It also scans for ABS fault code readings via industry-standard blink codes on all major trailer brands with no software, subscriptions or hardware adapters or transceivers locked to a specific brand or device.
Theriault has a degree in computer science, but he was the technician at the back of the trailer inspecting for faults long before he began building Trailer Dr. He worked in the shop at his father’s on- and off-road lumber-hauling fleet for 30 years.
He said he built Trailer Dr. because there was nothing on the market that did what he needed.
“I've always dipped my hands into electronics and was always curious about technology,” Theriault said. “I built this tool because I worked on trailers, and I knew exactly what I wanted.”
He started with a primitive prototype: a device with manual switches that converted alternating current (AC) from a wall outlet to direct current (DC).
Trailer Dr. is a plug-in device rather than battery-operated, Theriault said. He also noted that it relies on electronic rather than thermal circuit protection, reducing the danger of damage from a short circuit caused by snowmelt.
