the output tester 137
By Lite-Check
next gen trailer & truck diagnostics
Modern fleets expect more from their equipment — especially those pulling doubles or running dollies. The 137 Output Tester doesn’t just verify output at the truck; it confirms that electrical and air supply continue all the way through the trailer and out the back end where another trailer or dolly connects.
Whether you’re hauling one trailer or three, the 137 proves that your equipment can pass enough power and air down the line to safely support the next unit. No weak links. No guessing. Just verified throughput front to back.
Stimulate actual operating conditions
Electrical systems behave differently under load, and that’s where the 137 shines. In Truck Output Mode, you apply a controlled electrical load at the truck’s 7-way to check for voltage drop, weak circuits, or failing connectors. Then, with a quick flip of the switch, Trailer Throughput Mode applies that same real-world load at the rear of the trailer, telling you if power is being restricted or lost inside the trailer.
This dual-mode setup lets you:
See how the truck responds under true operating conditions
Compare front-end and back-end voltage instantly
Verify that the trailer can pass enough power to support another trailer or dolly
Catch wiring or connector issues anywhere along the chain
You can’t beat the clarity of seeing both ends of the system under identical load.
Electrical failures aren’t just an inconvenience — they can create unsafe operating conditions, road calls, and expensive downtime. The 137 Output Tester gives you a structured way to validate electrical output before a truck is paired with a trailer or sent out on a route.
By detecting issues early, fleets can avoid unnecessary parts replacement, prevent repeat failures, and extend the life of both trucks and trailers. Consistent testing helps support compliance with industry standards and keeps lights, ABS, and related systems powered the way they were designed to be.
PROTECT FLEETS FROM COSTLY ELECTRICAL FAILURES
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The 137 simulates real electrical loads at the truck’s 7-way connection and checks voltage performance under load. It also verifies air output and warning system operation. Instead of just checking for power, you see whether the system can hold that power under real-world conditions.
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Fleets, repair shops, and OEMs that want fast, reliable diagnostic results. If you maintain or build trailers and need to confirm a truck’s output performance before it hits the road, the 137 gives you a repeatable and trustworthy way to do it.
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By pinpointing whether electrical issues come from the truck, the wiring, or the connection hardware. Techs skip the guesswork, avoid unnecessary parts swapping, and get equipment road-ready faster with fewer comebacks.
output tester 137
look at what others overlook.
Discover the simplicity and accuracy of the Lite-Check 137 Truck and Trailer Output Tester. Designed for effortless use, this essential tool provides technicians with precise output readings for commercial trucks, trailers, and dollies. Simply attach the included 7-way cable and gladhands to the output receptacle of the vehicle, and the tester delivers accurate air and electrical readings on its clear 4.75” x 1.75” LCD screen.
Engineered for efficiency, the Lite-Check 137 ensures reliable diagnostics, helping you maintain optimal performance and safety. Streamline your testing process and trust Lite-Check for superior quality and dependability.