04:14 27-11-2025

Find a broken wire with a multimeter: a zero-cost trick

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Learn a fast, zero-cost way to locate a broken wire using a multimeter and DIY probe. Find cable breaks with a switching power supply, no tracer needed.

Wire breaks are a common headache in gear where the harness keeps bending—motorcycles, household appliances, portable tools. Replacing the entire lead isn’t always feasible, and professional cable tracers can be pricey, so a quick, zero-cost way to pinpoint the fault is worth having.

A regular multimeter will do

You don’t need specialist kit to check for a break. A multimeter that most home tinkerers already own is enough. Even the most basic model has everything needed for this search.

How to prepare a probe for the search

Remove the multimeter’s negative lead and attach a short piece of wire—thin strand or bare conductor both work. Make sure the contact is tight; a small cap on top adds convenience. That’s your DIY search probe done.

Multimeter setup

Switch the meter to AC voltage. Connect a switching power supply to the broken wire. In the example, a 12 V screwdriver charger was used.

How the search works

Make a couple of turns from the wire to form a mini-coil. Hold it between two fingers and sweep along the cable under test. Touching it with your fingers reduces interference and stabilizes the readings. Closer to the power supply, the multimeter shows roughly 190–200 mV. As you move the turns along the cable, watch how the values change. At the break, the voltage drops by almost half—and it happens abruptly, within a very short segment.

Why this method works

The switching supply creates a weak alternating field that the wire turns pick up. At the break, the signal changes, and the multimeter records a drop in voltage. This makes locating the fault fairly precise.

Practical use

This trick helps when a single conductor inside a shared jacket is damaged with no outward clues. It’s convenient in wiring looms where replacing the entire run would take time. In practice, it has saved technicians during repairs more than once.