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How do I test a car speaker wire polarity with a multimeter?

I just installed a new sound system in my car and now my front passenger speaker has poor sound output. I think the speaker might be bad, but before I return it, my friend told me to test the polarity. How do I test a car speaker wire polarity with a multimeter?

avatar
Eric Schad · Updated on
Reviewed by Shannon Martin, Licensed Insurance Agent.
Sorry to hear that your speaker is performing poorly! In most cases, you may have just switched the positive and negative wires from the vehicle to your speaker. So grab a multimeter, attach the leads to each wire, and look for positive voltage.
To test the car speaker wires using a multimeter:
  • Remove the car door paneling so you can access the speaker.
  • Remove the speaker from the car’s internal wiring and set it aside.
  • Grab your multimeter and turn it to the 200-millivolt setting.
  • Attach a lead to each wire inside the door.
  • If the numbers on the multimeter are positive, make a note as to which lead is on which wire. Connect the positive (red) and negative (black) wires from the speaker to these wires from the sound system.
  • If the numbers on the multimeter are negative, you have the leads on the wrong terminals. Simply switch the leads on the wires to get the correct positive and negative wires.
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sound system
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