The Check N Tow Pro is our heavy-duty trailer light tester for semi trucks and commercial trailers. Plug a trailer into the standard 7-way round socket and check every lighting circuit right at the trailer, no tractor needed. Built for fleet shops, truck stops, and drivers.
Every commercial circuit
Dedicated buttons for Left Turn, Right Turn, Brake Lights, Tail/Tag, Clearance, and ABS/AUX.
7 automotive relays + flasher
Seven automotive-grade relays switch the circuits, and a built-in flasher gives turn signals a true flash, just like a real tractor.
Lighted stainless push buttons
Heavy-duty silver buttons light up when active and stand up to gloves, grease, and daily shop use.
Built-in voltmeter + circuit protection
A digital voltmeter shows battery voltage at a glance, and a resettable breaker protects the unit.
Runs on your tool batteries
Powered by 18–48V cordless tool batteries like DeWalt and Milwaukee, so you can test anywhere.
Works with LED + incandescent
Consistent, reliable testing across bulb types.
Hand-assembled in the USA
Every Check N Tow is built and tested in our shop before it ships.
Check N Tow Pro: Semi Truck Trailer Light Tester
Every Check N Tow housing is 3D printed and hand-assembled in our shop in the USA, and every unit passes a full function test and a cosmetic inspection before it ships.
Because of the printing process, your housing may show small cosmetic marks, such as fine layer lines, light surface wisps or slight texture variation. These are a normal part of how the housing is made and don't affect its strength, durability or performance.
Anything that affects how your tester works is covered by our 1-year limited warranty.