Check each Subwoofer or Speaker that isn’t working for continuity - At the subwoofer or speaker, one at a time, test the terminals for Continuity using your Digital Multi-Meter; if your DMM doesn't have a Continuity test, use the Resistance, or Ohms, test and check for Resistance in the Subwoofer Coil (be sure to disconnect the subwoofer wiring before performing these tests).
- If they test out good, hook the wires back up and test the terminals at the terminal cup or at the Amp hookup if you didn’t use a terminal, don't hook it up to the amp yet. Sometimes the wiring inside the box can be a problem if it has come loose, or isn't making a great connection.
- If you have a Sub or multiple Subs with Dual Voice Coils, or multiple Subs with Single Voice Coils, make sure your wiring is correct by checking here: http://www.the12volt.com/caraudio/woofer_configurations.asp
- Make sure there are no Hi-Pass filters, crossovers, or multi Channel switches enabled.
- Replace your RCA cable/s with known working RCA cable/s from the Source/Head Unit to the Amplifier/s.
- Check your Head Unit settings; make sure the Bass is turned up and/or the Subwoofer setting is turned On.
- If you are still getting no output, try plugging in an MP3 player or CD player using a headphone to RCA adaptor and check for sound output. If there is still no output, your Amplifier outputs are probably burned out.
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