How to distinguish positive and negative on speaker wires?
2 Answers
When the speaker cone retracts inward, the battery positive terminal corresponds to the negative terminal on the speaker; vice versa for positive. Set the multimeter to ohmmeter mode and touch both terminals to the speaker's two poles. When contact is made, the speaker will move slightly - forward movement indicates the standard positive terminal, while backward indicates negative.
When distinguishing between the positive and negative wires of a car horn, I usually start by checking the cable colors: in most factory-installed setups, the red wire is positive, while the black or white wire is negative. However, aftermarket modifications might mix up the colors, so I use a voltmeter to verify—black probe to the car body (ground) and red probe to the wire. A positive voltage reading indicates the positive pole. If no tools are available, I briefly touch the wire ends to a small battery and observe the horn cone movement: forward motion means correct polarity, while reverse motion causes distorted sound. During repairs, I always consult the vehicle owner’s manual for wiring diagrams to avoid mistakes. Reversed polarity not only degrades sound quality but can also blow fuses—I learned this the hard way after hours of troubleshooting. Remember: disconnect the battery before any work to prevent short circuits—safety first!