TOPDON releases CT100 Circuit Tester

This tester is designed to diagnose circuits on cars, trucks, and motorcycles.

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May 13, 2026

2 min read

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TOPDON USA has released the Circuit Tester, No. CT100, an electrical testing tool for diagnosing the circuits across cars, trucks, and motorcycles. This tool features a clear digital voltage display with built-in load testing.

The CT100 features a real-time digital display that offers ±0.1V accuracy from 3.3–60V and ±0.2V from 60–65V. Its dual-color backlighting clearly identifies positive and negative polarity to help prevent reverse connections. Additional audio and visual alerts provide immediate feedback for high voltage, overheating, and reverse polarity, with an additional tone to confirm circuit continuity and avoid the need to constantly monitor the screen. The CT100 has a standard 4mm banana jack that allows quick switching between clips and features a durbale, heavy duty alligator clip for consistent performance during repeated use.

This tester comes with a 12.5' for greater reach when working around vehicles and a convenient carrying bag.

A word from TOPDON

“The CT100 Circuit Tester is a simple-to-use, versatile diagnostic tool built for everyone from weekend DIYers to professional technicians,” said Chad Schnitz, Vice President of TOPDON USA. “What sets the CT100 Circuit Tester apart is its load testing capability. Our team engineered it to measure DC volts from 3.3V to 65V, allowing it to quickly identify weak connections, voltage drops, and wiring faults. With the CT100, you can go from ‘I don’t know’ to ‘I can fix it’ in no time.” 