How to use a clamp meter on a car

How to Use a Clamp Meter on a Car?

While I’ve written attentively on digital multimeters, we haven’t discussed clamp meters much yet so I wanted to take some time to introduce them and show you how you can use it on your car.

What is a clamp meter?

While most people are familiar with digital multimeters, they may not have experience with clamp meters.

To sum this up in a few words, a clamp meter is a current measuring tool whereas a digital multimeter is a voltage measuring tool. 

While they both primarily measure those, they also cross over and each has current and voltage measuring abilities but with one as the forte.

clamp meter allows you to clamp to a wire or cable at any point get a current reading on the measurement of the current without breaking the circuit. 

How to use a clamp meter?

Here are the basic instructions on how to use your clamp meter.

  1. Chose what you’re going to test. When using a clamp meter, the circuit should be connected and powered or else it won’t work properly.
  2. Select the appropriate function and range that you need to measure. Clamp meters are meant to measure only lower voltage readings below 600V. If you are unsure what the range is, you can always select a higher range and then lower it as needed. Additionally, make sure you are measuring the proper DC or AC current.
  3. Clamp the meter on to the conductor by pushing the trigger to open the jaws. Depending on your clamp meter you either will clamp it on to the wire or just place it around the wire without clamping down and wait for the reading.

Examples of clamp meter uses on a car

For some specific examples, if you want to measure the DC amps of the power being pulled from your new car audio amplifier. Ensure your meter is measuring in DC amps as some only measure in AC only.

Open the clamp meter and put the wire in the middle of the clamp with the wire passing through (but not clamped down). Then turn up the volume of the speakers and watch the measurement change on the clamp meter to reflect the change in current going through it.

This is a prime example of why you’ll use a clamp meter versus a digital multimeter as a multimeter cannot measure live circuits like this.

You can also use your clamp meter to test the current going to the headlights of on your car. Simply clamp the meter over the wires going to your headlights. You can then turn the lights on and off and turn on your bright lights and dim lights to see the difference in current being used.

What else can a clamp meter read?

You can also measure things outside of current including voltage and resistance.

This will always depend on the clamp meter being used what functionality it has, but typically it’s standard that it can measure other things outside of just current.

  • Voltage: If you want to measure voltage using your clamp meter, you won’t actually use the clamp. That is why most clamp meters also come with test probes to measure AC/DC voltage. Plug in the probes using the same steps that a digital multimeter would (black going into the COM and red going into the voltage jack). Select the range and touch the tips of the probes to the conductor to get your readings.
  • Resistance: This is mostly the same process as measuring voltage, but instead the circuit being live you’ll want to ensure that the power is off. Resistance measurements must be done with no power as you’re determining how much the current is being blocked. When measuring resistance, you need to be very careful on clamp meters because it could cause damage to your meter if the power is on.

How to properly maintain your clamp meter?

Most meters whether a clamp or digital meter is expensive, especially if you have a Fluke meter. That’s why it’s always important to ensure you properly maintain it.

The first thing is to make sure it’s always stored properly in a dry and clean place to ensure both moisture and dust does not harm the multimeter.

Additionally, do not ever force your multimeter apart. The magnetic circuit will typically automatically self-align on its own as this is a standard built-in feature. If you start to pull the meter apart you can destroy this functionality.

What are the best clamp meters?

There are many clamp meters on the market, so I wanted to review some of the best ones with you to help make it easier to determine which you’ll use.

Fluke 323:

The Fluke brand is one of the most respectable ones on the market today not only for digital multimeters but also for clamp meters. Both home users and professionals rely on their products for their accuracy and reliability. 

The 323 has the ability to measure AC and DC voltage, current, resistance, and does these with very fast speed and accuracy. The 323 makes an audible tone upon completion of measurement so you know when it’s finished.

Amprobe AMP-210: 

The Amprobe are known to be an overall good package including all of the necessary measurement capabilities you’d need on a clamp meter. 

It can measure both DC and AC voltage, resistance, and surprisingly you can measure capacitance on the 210.

Tekpower UT202A: 

This is a very affordable alternative to other clamp meters. It can still measure AC/DC voltage, resistance, and continuity. 

It also has the hold functionality and a carrying case typically for proper maintenance.


If you’re trying to decide which to purchase, here’s the breakdown. 

If you need a clamp meter for professional use, go with the Fluke 323 for accuracy and reliability.

If you need one with the most functionality, then go with the Amprobe 210 for its diversity. 

If you just need a cheap one for home use, then go with the Tekpower UT202A due to its affordability although somewhat lacking accuracy.

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