How to Test Electrical Circuits in a Car

How to Test Electrical Circuits in a Car

The current from the battery to the electrical components is supplied through an elaborate network of wiring systems, making an electrical circuit. If a circuit breaks down, the flow of supply is disrupted, and the electrical component stops working. Testing an electrical circuit with a continuity tester can help you differentiate between a damaged and a complete circuit. However, there are many other multi-functional tools you can use to identify a faulty circuit. Read on to learn how to test electrical circuits in your car using special testing tools and fix faults in the electrical system.

Safety Warnings

  • You should always be careful while working on the car’s electrical system. The high voltage of the battery can cause electrocution if not dealt with carefully.
  • You should work carefully on the wiring system of your car. Damaged wires can cause short-circuiting in the system, resulting in a fire accident in the car.

Tools for Testing

Electric circuits in a car can be tested using many different tools depending on your budget and requirements. Regular testing can ensure that your car’s electrical components function properly. Missing voltage in a circuit can easily help you identify the problem area. Following are some of the most common tools used for testing circuits.

Continuity tester

A continuity tester is a battery-powered device with an alligator clip on a chord and a probe at the other end. To test a component with a continuity tester, disconnect the power. For testing, earth the clip by placing it on the car’s body and place the probe on the live side of a component and see if the tester lights up. If it fails to light up, either the wiring is faulty, or the fuse has been blown. To check if the continuity tester is working, place the clip on the probe and check if it lights up.


A multimeter is a battery-operated multi-purpose tester that can provide you with an accurate reading of resistance, frequency, capacitance, AC and DC voltages, and continuity of an electrical circuit. You can use the multimeter to check the electrics of a car.

It has two metal probes, a dial through which you can change modes, and a digital screening that shows readings. Due to its versatility, it is an expensive tool but worth having for the accuracy of its readings. It is advisable to read its manual to learn its functions, which otherwise might seem complicated.

Circuit tester

A circuit tester is a simple tester that has two leads with metal probes on them and a neon light inside it. The circuit tester can only tell if there is voltage present in an electrical circuit or not. A metal probe is placed on a terminal or hot wire, while another probe is placed on a ground or neutral contact. If the voltage is detected, the circuit tester lights up. It is very convenient to use since it does not run on a battery but can only identify broken circuits, not the faulty ones.

Inductance tester

An inductance tester is a small battery-powered device that detects voltage without coming in contact with any wire or electrical component. The inductance tester works like a wand, making it very safe and easy to use. You can stick the pointy end of the device on any area of a wire or an outlet of an electrical component to get an approximate reading of the voltage and a red-light indicator.

Since the device is battery run, make sure it is charged before testing. You can test it on a live outlet to ensure the device is working.

Solenoid tester

Solenoid testers are a simpler version of multimeters and are capable of reading voltage and polarity. These testers can measure both AC and DC voltage from 100-600 volts to an approximation. Since it does not require a battery to run, you can easily use it without worrying about it running out of power. It has two probes that are used to detect voltage. If the voltage is detected, the tester starts to vibrate or makes a clicking noise to let you.

Digital clamp meter

A digital clamp meter is an expensive tester that works like a multimeter and has a current sensor. It is safer to use and can easily test circuits individually because of its jaw-like clamps. These clamps hold the wire conductors inside them. It also has additional probes to be used as a regular multimeter. 

Wand voltage meter

A wand voltage meter is a combination of a circuit tester and an inductance test, but unlike the other two testers, it gives an exact reading of a circuit’s voltage. It has metal probes that can be placed on terminals or naked wires. It also has electrostatic wands that you can use to detect voltage by hovering them over the wires or the metal terminals.

Finding Faults in the Electrical System.

An electric circuit must be complete for the current to flow through it. If a component in your car stops working, you need to trace its circuit. Color-code wires and following the connection paths can help you find the dead circuit.

Knowing how to test electrical circuits with the right tools can help you identify any faulty electrical components in your car. An appropriate testing tool is a one-time investment that can ensure that your electrical system works properly and save you a huge amount of money that you’ll otherwise have to spend on the mechanics.