Test Light vs. Multimeter: Pros and Cons

Electrical issues with a motorcycle, ATV or side-by-side are usually easy to diagnose and resolve using the right electrical testing tools.

Test lights and multimeters are two essential tools you should keep in your toolbox to deal with electrical repairs and maintenance work. Both serve similar purposes, and are often employed in tandem to diagnose electrical problems. We'll show you some practical uses for each tool, and compare them both to help you decide whether you need one, the other or both. 

Test Light

A test light is a simple, yet effective tool for identifying whether electricity is present in a component or part such as a battery or a regulator/rectifier.

If you need to determine quickly whether a particular part or component has electrical voltage or has shorted to ground, the test light is the ideal tool for the job. However, these functions are just about the extent of a test light's capabilities, as it is unable to measure the amount of voltage, amperage, or resistance in an electrical circuit.

Check Battery Voltage with a Test Light

Dead battery? Use a test light to see if it has any voltage. Put the clamp end of the test light to the negative side of a battery, and put the probe end of the test light to the positive side of the battery. The test light will illuminate if there is any electricity present, so you'll know the battery has voltage, just not how much.

Check For Grounds with a Test Light

Put the clamp end of the test light to the positive side of a battery, and put the probe end of the test light to various points along the circuit such as wires, fuses or connectors. If the test light illuminates, you'll know electricity is present and the circuit is good. However, if it doesn't illuminate you'll know electricity is not present and the circuit has grounded.

PRO TIP: Using a test light to test for grounds in fuel injection systems is not recommended because the fuel injection system is governed by the ECU, which can easily be damaged by a ground circuit created by the test light.

Test Light Pros and Cons (vs Multimeter)

Pros

• Easier to use 
• Cheaper to buy
• More compact

Cons 

• Much more limited capabilities
• Cannot measure electrical values
• Can damage sensitive components if misused

Multimeter

A multimeter is a precision tool for measuring electrical force (volts), current (amps) and resistance (ohms), as well as several other readings such as capacity, frequency and conductance, depending upon the multimeter model.

If you need to determine more than the mere presence of an electrical voltage, a multimeter is the only tool for the job. Top-of-the-range multimeters with a wide variety of automatic functions can cost several hundreds of dollars. However, a high quality multimeter for practical use on your motorcycle, ATV or UTV can be purchased inexpensively.

Test Battery Voltage with a Multimeter

Set your multimeter to the voltage range for the battery being tested. A typical motorcycle battery, for example, would use the 20-volts DC setting.

Put the negative lead from the test probe to the negative side of a battery, and put the positive lead from the test probe to the positive side of a battery or electrical circuit. The multimeter's screen will display the precise voltage reading.

Testing Regulator/Rectifier Diodes with a Multimeter

Set your multimeter to the diode setting. Put the negative lead from the test probe to one terminal from a diode, and put the positive lead from the test probe to another terminal from the diode. The multimeter's screen will display the precise voltage reading.

Multimeter Pros and Cons (vs Test Light)

Pros

• Wide range of functions and capabilities
• Can measure a variety of electrical values

Cons

• More expensive to buy
• Not as easy to use

Test Light vs Multimeter Summary

Should you get a test light or a multimeter? Your best bet is to invest in both. The test light is so quick and easy to use for detecting electrical power that it should be an essential inclusion into any mechanic's toolkit. However, the shortcomings of the test light make the multimeter an invaluable addition to any garage or workshop.

Now that you know the differences between a test light and a multimeter, let's compare the multimeter to another electronic diagnostics tool: the battery tester. Watch the video below to learn about the differences between a battery tester and a multimeter.