How to Test Car Speaker Wire Polarity with Multimeter

Car audio systems can often be complicated to diagnose and repair since they are so difficult to access. The speaker wiring is usually tucked away in the engine bay, which necessitates removing panels and other body components that could expose sensitive areas of the vehicle such as gas tanks or brake lines.

The best way to troubleshoot these systems is through testing for “speaker-to-ground” continuity using a multimeter.

If you’re not sure how to test car speaker wire polarity, don’t worry! This blog post will show how to test car speaker wire polarity with multimeter.

What is speaker wire polarity and how does it work?

Speaker wire polarity is how the positive and negative terminal on an audio system is connected. The speaker itself will have either a “+” or “-” sign stamped into its exterior casing to denote how it should be wired in.

With negative polarity, the black probe is connected to the amplifier’s “-” terminal. The red probe connects to the “+” terminal on your car speaker wire.

Otherwise, you might see some colored wires coming out of each terminal instead. These indicate which ones are for ground (usually black) and which ones are for power (usually red).

Analog or Digital multimeter: Which is best for testing car speaker wire polarity?

Analog multimeter is the best for testing correct polarity, as these meters have a feature to measure continuity.

Digital ones usually don’t display the resistance in ohms (Ω). Instead, they’ll beep if there’s no connection or display infinity (∞) which is not helpful when measuring speaker cable.

Sometimes you can change it on the digital multimeter to display resistance in Ω if you want, but it’s not always simple. However, it’s essential to keep in mind that you should buy a multimeter that is under $100 to save extra money.

How to Test Car Speaker Wire Polarity with Multimeter?

What Tools Do You need?

  • A multimeter
  • A pair of wire strippers
  • The speaker’s wiring harness

Note: A multimeter is an essential tool for any car audio installation or repair project. There are many different types on the market, but how do you know which one to buy? For our testing, we took a cheap multimeter for $50.

Top 6 steps to follow to test car speaker wire polarity:

Step 1: Disconnect the speaker

Disconnecting a speaker is often as simple as removing a few pieces of wiring or unfastening some clamps. You may need to remove larger components such as panels, but this depends entirely on how your car’s audio system has been set up.

Step Two: Turn off all vehicle power sources

Turn off all power from the vehicle, including interior lights and other smart devices. This will prevent you from getting shocked while working on your car’s audio system.

Step Three: Connect the wires to the battery

Select either the DC Voltage or the AC Voltage setting on your multimeter. Battery power is measured in DC, so this one setting is all you need because your car runs on battery power.

Step Four: Touch the probe with ground wire and speaker terminal

Touch the red probe to the ground wire or car metal, and then touch the other probe to each speaker terminal.

When your speakers are working correctly, you will get a reading similar to how the wires are connected.

If the speaker is wired counterclockwise, your reading should be positive. If it’s wired clockwise, you’ll get a negative reading.

Step Five: Compare results for all speakers

Repeat for all speakers and compare results to see how they’re working. You should remember that some cars have two sets of positive and negative wires coming into each car speaker.

In this case, each probe should be connected separately to a positive wire and a negative wire.

Step Six: Change any faulty parts

Replace any faulty components and enjoy how loud they are. If there is not enough continuity around all terminals, the issue is most likely either the speaker itself or the speaker wiring. You should replace both if these tests do not solve your problem.

If the speaker is working correctly, you’re good to go. Just reconnect everything and enjoy how loud they sound.

Realated: 6 Best Multimeter Under 100 Dollar of 2022 (Buying Guide)

Frequently Asked Questions (FAQs): Speaker Wire Polarity Positive Negative

Which battery voltage is best for testing car speaker wire polarity?

Answer: A 9v battery works best for this test, but be sure to take it out of the device you’re using before performing any tests.

Does it matter which speaker wire is positive?

Answer: Yes. It matters because the speakers are polarized. The positive speaker wire will send a signal to one part of the speaker cone, which causes it to move forward and push air out of the back.

This process creates sound waves that you hear as music or speech from your radio station or CD player. If both wires are attached incorrectly, then you’ll have no sound coming from the speakers.

What happens if you mix up positive and negative speaker wires?

Answer: If you mix up positive and negative speaker wires when connecting them to the amplifier, the sound will not be able to pass through.

What’s the direction of current flow in the speaker wire?

Answer: The speaker polarity can be tested with a multimeter that has continuity tester mode or ohmmeter mode. Put one probe on each terminal, and you should see zero (0) resistance if it is correct.


There you’ve the details on how to test car speaker wire polarity with multimeter. It should be easier for you to diagnose the issue and get your sound back. This is one way to avoid spending money on new speakers.



Shawkat is a passionate home and auto mechanic who enjoys sharing his knowledge with others. He has been working on cars and homes for over 9 years and has a wealth of experience to share. From indoor tools to outdoors, crafting to automotive, you will see his passion for tools. And he is not alone here, either. He collaborates with other users to give you the best possible tool experience. As the founder of Geartoolsbuddy, Shakat is always happy to help people with their queries and doubts about power and hand tools.