Faulty speaker wire is one of the more common problems that can cause your speaker system to malfunction. Particularly in systems with speakers spread across long distances, broken wires and/or poorly connected speakers often can occur when there is a lot of length of wire in use. Although fixing a broken or poorly connected wire is not difficult, it can be a challenge to find the problem. A few methods are available to locate the bad wiring.
Connect one end of your voltmeter to the negative (-) port of your speaker. Connect the other end to the (-) port of the stereo receiver to which the wire should be connected. If you have wired the (-) line of this speaker properly, the voltmeter will indicate that you have completed a circuit. Typically voltmeters light up or beep when a circuit is completed, but each meter is unique. Perform this test with the positive (+) ports of the speaker and the receiver as well; the voltmeter should also indicate a completed circuit. Repeat this step with every speaker.
Disconnect the voltmeter from the stereo receiver if the meter indicates that you have not completed a circuit, and systematically connect the meter to each of the speaker ports. If you have done the wiring correctly, then the meter will indicate that none of these ports complete a circuit. However, if the meter indicates that one of these ports complete a circuit, then you have connected a wire to the incorrect port. If this does happen, then disconnect the wire which completes the circuit from the stereo receiver, and connect it to the port that it should be connected to (in other words, if the wire's mate is connected to a (-) port of a left front speaker, then the errant wire is meant to be connected to the (+) port of the left front speaker).
Check the connection of the speaker wire for each speaker by gently tugging on the wire where it connects to the terminals on both the speaker and the receiver. If you have poorly connected the speaker wire, you will notice that the wire will come loose from the terminal easily. Poorly connected wiring also will appear frayed and uneven at the tip where it is exposed.
Run a new wire from the speaker that is giving you problems to any available port. If the original speaker wiring is faulty, the new wire will produce good quality sound. However, if the problem persists, there is nothing wrong with your original wiring. The issues being created are most likely due to an issue with the receiver or the speaker itself.
Disconnect any power running to the speaker system before beginning any wiring work to prevent any accidental short-circuiting.