Automotive Circuit Testers & Electrical Diagnostic Tools

Automotive Circuit Testers & Electrical Diagnostic Tools — Australia

Diagnosing automotive electrical faults requires more than just reading fault codes — you need to test circuits, activate components and trace wiring at the source. AZscanners stocks a comprehensive range of automotive circuit testers and electrical diagnostic tools from trusted brands including Allosun, GODIAG, Hantek and Autel — covering everything from basic test lights and power probes through to OBD breakout boxes and ultrasonic leak detectors.

What Is a Circuit Tester?

An automotive circuit tester is a tool used to check for the presence of voltage or continuity in a vehicle's electrical circuits. Unlike a multimeter which gives you a precise reading, a basic circuit tester gives you a quick pass/fail indication — making it fast and practical for tracing faults on the workshop floor. More advanced circuit testers such as power probes can both test and activate circuits, allowing you to power components directly from the tool to check whether a relay, solenoid or motor is working independently of the vehicle's wiring.

Types of Circuit Testers & Electrical Diagnostic Tools

Power probes — the most versatile circuit testing tool for workshops. The GODIAG GT101 and Autel PowerScan PS1 both power and test circuits on 12V and 24V vehicles — letting you activate components, check for power and ground, and measure voltage without needing a multimeter.

OBD breakout boxes — used to access and test individual pins on the OBD2 diagnostic port without risking damage to the connector. The GODIAG GT100 and GT100 Plus are essential for workshops diagnosing communication faults or verifying ECU power and ground supplies.

Glow plug testers — the Allosun EM271 tests diesel glow plugs quickly without removing them from the engine — a simple but highly useful tool for any workshop servicing diesel vehicles.

Wire tracers & short circuit detectors — the Allosun EM415Pro traces wiring faults through walls and looms, identifying shorts, opens and broken circuits quickly without needing to strip back wiring.

Ultrasonic leak detectors — the Allosun EM2268 detects vacuum leaks, exhaust leaks and air conditioning leaks using ultrasonic sound — a non-invasive diagnostic tool that can locate leaks that are invisible and inaudible under normal conditions.

FAQs — Automotive Circuit Testers

What is a power probe and how does it work?

A power probe is a handheld circuit tester that connects directly to the vehicle's battery and allows you to both test circuits and apply power or ground to any point in the vehicle's wiring. This lets you activate relays, solenoids, motors and other components directly to test if the component itself is working, independent of the vehicle's control system. It's one of the most time-saving tools available for diagnosing electrical faults in a workshop environment.

What is an OBD breakout box used for?

An OBD breakout box sits between the scan tool and the vehicle's OBD2 port, exposing all 16 pins so they can be individually tested with a multimeter or oscilloscope. This allows you to check whether the vehicle is providing correct power, ground and communication signals to the diagnostic port — useful when a scan tool won't connect and you need to determine whether the fault is in the vehicle's wiring or the scanner itself.

How do I find a short circuit in my car's wiring?

The most efficient method is a combination of a circuit tester and a wire tracer. First isolate the affected circuit using the circuit tester to confirm power is present up to a certain point, then use a wire tracer like the Allosun EM415Pro to follow the wiring through the vehicle and identify exactly where the short or open circuit is located. For more complex faults, an oscilloscope can also identify irregularities in signal waveforms that point to wiring damage.

Can a circuit tester damage my vehicle's electronics?

A basic test light or probe used to check for voltage will not damage modern vehicle electronics provided it is used correctly. However applying incorrect voltage or grounding through sensitive ECU circuits can cause damage — this is why professional-grade power probes include built-in over-current protection and fusing. Always follow the product instructions and avoid back-probing sensitive ECU connectors directly without using the appropriate breakout leads or adapters.

What is an ultrasonic leak detector used for in automotive diagnostics?

An ultrasonic leak detector converts high-frequency sound — inaudible to the human ear — into an audible signal, allowing you to locate vacuum leaks, intake leaks, exhaust leaks and air conditioning leaks quickly and accurately. It is particularly useful for finding small vacuum leaks that cause rough idle or lean running conditions, and for locating air conditioning leaks without the need for dye or refrigerant detection equipment.

Need Help Choosing a Circuit Tester?

Our team is here to help. Whether you need a basic power probe for a home garage or a full breakout box for a professional workshop — get in touch and we'll find the right tool for you.