Continuity Voltage Tester: A UK Buyer's Guide

Short answer: a good continuity voltage tester does two jobs in one — it confirms whether a wire is live (and which way round) and whether a circuit is unbroken end to end. For classic-car and older-vehicle work, where the wiring colours have faded and earths corrode, that combination is far more useful than a bare test lamp.

Anyone rewiring an older car knows the feeling: “the old wiring colours have faded to the same brown” and you are tracing a circuit by hand, section by section. A tester that signals with a tone as well as a display means you can follow a wire without “staring at a tiny screen through reading glasses” the whole time.

Voltage and continuity: why you want both

Voltage testing tells you a point is live and shows polarity. Continuity testing tells you a path is complete when the power is off — essential for checking earth straps, switches and suspect sections of loom. On a classic, most gremlins are breaks and bad earths, so continuity is the mode you will lean on most.

Chasing a bad earth

Corroded or lost earths cause the strangest symptoms on old cars — lights that dim when the indicators tick, gauges that read wrong. A continuity check to 200 kOhm on the PowerScan PS100 confirms whether an earth is actually solid instead of guessing from flickering symptoms.

Tone matters more than you think

Being able to hear a result rather than read it is a genuine help when you are under a dashboard with your head at an awkward angle. It keeps you moving along the wire, which is exactly what you want when the job is following a circuit rather than taking one reading.

Protecting rare and irreplaceable parts

On a cherished classic, the fear is real: nobody wants to damage an irreplaceable instrument. Simple continuity and voltage checks are gentle, and the PS100 has a high-impedance mode for anything sensitive. It is a careful tool, not a brute-force one.

Beyond a basic test lamp

A cheap test lamp only tells you a point is live, and can even mislead on a loaded circuit. A proper continuity voltage tester adds the readout, the tone and the continuity mode — the reasons owners upgrade once a loom job gets serious. To learn the tool hands-on, read how to use a power probe, and for general fault chasing see our car electrical tester guide.

A continuity voltage tester that suits older eyes and older looms

The Autel PowerScan PS100 is a 30 g continuity voltage tester that reads 0 to 65V and continuity to 200 kOhm, with tone and a clear TFT colour display (160 x 128) so you can follow a wire without staring at a screen. It has an integrated LED work light for dim garages, a 6-metre lead to reach around a classic, and a high-impedance mode to protect irreplaceable instruments. It covers 12V and 24V systems and runs off the vehicle battery. It is GBP 212.49 inc. VAT with Free UK Delivery, 30-day returns and a 12-month warranty plus UK support, rated 4.8 out of 5 from 300 reviews.

Frequently asked questions

What is the difference between a voltage tester and a continuity tester?

A voltage tester tells you a point is live and shows polarity; a continuity tester tells you a circuit is unbroken with the power off. A combined continuity voltage tester does both, which is what older wiring and earth faults usually need.

Is a continuity voltage tester good for classic-car wiring?

Yes. On older looms the colours fade and earths corrode, so being able to confirm both a live feed and an unbroken path, ideally with a tone as well as a display, makes tracing faults far quicker than a bare test lamp.

Can I use it without damaging rare instruments?

Simple continuity and voltage checks are gentle, and the PowerScan PS100 has a high-impedance mode for sensitive components. It is designed for careful diagnostics rather than heavy load testing.

Why choose this over a cheap test lamp?

A test lamp only shows that a point is live and can mislead on a loaded circuit. A continuity voltage tester adds a clear readout, a tone and a continuity mode for checking earths and broken runs.