at park, turn the stereo on.
Bring all the way down the treble, and turn all the way up the bass.
find a hip hop station, or look for a song with lots of bass, turn the sound up. if the sound cuts off, than is the speaker has a broken wire from the bobine that is inside or the Outside wire that goes from the connector to the speaker is damage (Usually gets broken at the edfe of the speaker or the side of the connector terminals.
If the sound of the speaker does not cut off, than you might have a wire that is broken and making a false contact.