The Calterm 66331 Tru-Spark Ignition Firing Indicator is an essential diagnostic tool for professionals and DIY enthusiasts working on automotive, motorcycle, and powersports ignition systems. This innovative tester allows you to quickly and accurately test DIS and other ignition systems for the presence of secondary voltage without the need to pierce or remove spark plug wires, making it the ideal solution for troubleshooting "no-start" conditions. Engineered for the demanding environment of a professional garage, the unit features a rugged high-impact ABS housing that is resistant to oil and shop chemicals. Its compact, pen-style design includes a pocket clip for convenience, ensuring you always have a reliable diagnostic tool within reach. What sets this indicator apart is the exclusive Sensitivity Adjustment Dial. This feature allows you to fine-tune the tester to isolate a specific plug wire, effectively eliminating false signals from nearby wires—a common issue in modern, tightly packed engine bays. The dual-LED system provides instant feedback: a Green LED ensures the device is powered and ready, while a Red LED flashes in sync with the voltage release from the coil. With its 360-degree high-visibility indicator, you can view the firing sequence from any angle without your hand obstructing the light. Whether you are maintaining a daily driver, a high-performance motorcycle, or powersports equipment, the 66331 provides the precision and durability required for fast, safe, and effective ignition system diagnostics.

• EXCLUSIVE SENSITIVITY DIAL - Features a Sensitivity Adjustment Dial to isolate a specific plug wire and eliminate false signals from wires routed in close proximity for precise ignition testing.
• DUAL LED DIAGNOSTICS - The Green LED confirms the tester and batteries are operating properly, while the Red LED flashes each time voltage is released from the coil through the spark plug wire.
• 360-DEGREE VISIBILITY - Designed with a 360-degree high-visibility indicator so the technician's hand will not obstruct the view, allowing for easy monitoring of secondary voltage presence.
• RUGGED SHOP-READY DESIGN - Built with a high-impact ABS housing that resists oil and endures harsh shop conditions; includes a compact design with a pocket clip for easy portability and storage.
• PACKAGING NOTICE – This product may arrive with packaging labeled Calterm as branding transitions to nVent GARDNER BENDER. Product design, specifications, and quality remain unchanged during this rollout.
• 360 deg high visibility indicator so that technician's hand will not obstruct view