TOPDON CT100 Automotive Circuit Tester 3.3–65V

The CT100 is a professional automotive circuit tester built for speed and  accuracy. It helps diagnose electrical issues, identifies polarity, and provides clear alerts. Built rugged with a long cable and interchangeable probe,  it works on various vehicles. Fast, precise results for pros and DIYers.

Features

Professional Load Test

• Unlike basic test lights, our tester features a professional load test function (DC 5–30V, 1.2A Max). Hold the button for 5 seconds to check battery and circuit load capacity, quickly identifying aging batteries, weak connections, and voltage drops for faster, more accurate repairs.

Precision Voltage Testing

• Equipped with a clear backlit digital display, this professional circuit tester measures DC voltage from 3.3–65V with 0.1V resolution (±0.1V accuracy from 3.3–60V; ±0.2V from 60–65V). With a wider range than standard testers, it delivers dependable performance for both professional technicians and serious DIY users.

Polarity Protection & Anti-Reverse

• Dual-color backlighting (red for positive, green for negative) and on-screen ± indicators activate instantly when the probe contacts a circuit. This intuitive feedback helps prevent reverse connections and protects sensitive vehicle electronics during testing.

Safe, Battery-Free Operation with Built-In Protection

• Battery-free operation eliminates maintenance and downtime while improving safety during testing. Integrated protections include overvoltage alerts, overheating warnings, and component status monitoring for dependable performance in daily automotive diagnostic work.

Easy Operation &  Extended Test Lead

• The 12.5-foot extra-long test cable improves access to hard-to-reach areas without repositioning the tester. Universal 4mm banana plug connections support interchangeable probes and clips, enabling flexible testing across cars, trucks, and RVs.

Wide Vehicle Compatibility

• With a 3.3–65V testing range, this versatile tester supports 12V, 24V, and 36V vehicle systems, making it ideal for cars, trucks, and RVs. Perfect for checking fuses, verifying connector voltage, testing circuit integrity, tracing wiring issues, and diagnosing starting-related electrical faults.

Specifications

• Voltage Measurement Range: DC 3.3 V to 65 V
  
• Load Test: 5 V to 30 V (Max. 1.2 A)
  
• Measurement Accuracy: 3.3 V to 60 V: ±0.1 V/60 V to 65 V: ±0.2 V
  
• Measurement Resolution: 0.1 V
  
• Working Temperature: -10°C to 50°C (14°F to 122°F)
  
• Storage Temperature: -20°C to 70°C (-4°F to 158°F)
  

Packing List

• CT100 Tester
  
• 2mm Probe
  
• Alligator Clip
  
• Adapter
  
• Carrying Bag
  
• Quick User Guide