A Short Guide To Short Circuits: How To Spot One In Your Car

March 10th, 2022 by

A Short Guide To Short Circuits: How To Spot One In Your Car

We’ve all heard the saying: “Better the devil you know than the devil you don’t.” In a similar sense, when you’re driving, you should know how to spot an electrical short circuit. If you can identify one before it causes significant damage, you can save yourself a lot of time and money.

Here at Mazda of Fort Walton Beach, we want our clients to be as prepared as possible. So, we’ve compiled this guide on how to find a short circuit in your car.

Keep scrolling for more information!

What Circuits Does My Car Have?

There are two types of electrical circuits that your car has: the sensor and the actuator.

A typical example of a sensor circuit would be the wiring from the engine coolant temperature, or ECT, to the engine control module, ECM. This sensor tells the ECM what the engine’s coolant temperature is so that the computer can make decisions based on that information.

A demonstration of an actuator circuit would be a headlight. The headlight is an electrical device activated by a switch, which is supplied with voltage and current by the battery. When you switch on the headlight, it completes the circuit and allows current to flow to the headlights. The headlights then illuminate.

What Happens in a Short Circuit?

If any wire in these circuits is damaged or comes into contact with each other, it causes a short circuit. This occurs when too much current flows through a circuit, more than the component can handle. The excess current will cause the part to heat up and potentially fail.

Common reasons for damage and contact include:

  • A component worn out from age and use
  • Damage from corrosion or rust
  • Rodents chewing on the insulation of wires
  • Loose connections due to vibration
  • Exposure to extreme temperatures

How to Find a Short Circuit?

Caution: fiddling around with your car’s electronics can be dangerous. If you suspect there is short circuit in your car, we strongly advise you to bring in to an experienced car technician.

This procedure takes a lot of patience and a lot of concentration.

  1. Identify the circuit with the problem: look at where it goes, its connectors, and the color of its wires.
  2. Remove the affected fuse and connect the test light across the terminals of the fuse socket.
  3. If you’re using a multimeter, you can employ it similarly.
  4. Using a pair of pliers, disconnect the battery positive terminal.
  5. With the ignition off, use a test light to probe each connector in the circuit. Start at the load and work back toward the battery.
  6. If you’re using a multimeter, set it to continuity mode and touch one probe to one connector of the suspected short while touching the other probe to another connector in the circuit.
  7. If there’s a short circuit, the test light will glow when using a test light.
  8. If you’re using a multimeter, you’ll hear a beeping sound if there’s continuity between the two probes.


In this article, we’ve looked at different types of circuits you can find in your car, how to test for a short circuit and some of the causes of a short circuit.

If you think you might have a short circuit in your car, the best thing to do is bring it to a qualified mechanic. Mazda of Fort Walton Beach is proud to serve Niceville, FL, with quality solutions and repairs for all your car needs.

Schedule an appointment today!

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