Car Stereos: Car speakers turn off, car speakers, terminal connections

Question
i turned my car on the other day only to realize that my speakers were not playing just my subwoofers. after i turned the car off and back on they worked again but about a mile down the road they just shut off again all 4 of them i checked the wires on the head unit and i am stumped i dont know whats going on. the speakers are brand new (2 weeks old) and everything was fine until the other day.

Answer
Hi Travis,

Here's my guess:  one of the terminal connections at a new speaker has come loose, and is intermittently touching a metal surface in the vehicle.

Most after-market head units have an amplifier protection circuit that will shut down the sound to all the speakers if there's a short on one of the outputs.  This can be caused by a speaker wire shorted to ground.  Sometimes it's caused by a pinched speaker wire, or an uninsulated connection behind the head unit.  A blown speaker (with a shorted voice coil) can also be a cause.  However, given that your speakers are newly installed, I'd suspect that one of the terminal connections wasn't very secure, and has worked itself loose in the past few days.  If the wire then comes into contact with chassis metal, or even the speaker basket, then it's shorted to ground--a condition that will immediately trigger the head unit's protection circuit.

To troubleshoot a problem like this, I use a continuity tester (actually, the continuity function on a multimeter) at the speaker wires behind the head unit.  Connect one probe to a chassis ground point (dash metal, the head unit's ground wire, or the outer ring of the cigarette lighter all work) then use the other probe to test each speaker wire.  (The head unit should be disconnected during the testing).  If you find a speaker wire that shows continuity to chassis ground, then check the connections at that speaker.

Another method of troubleshooting is to disconnect all the speakers, then re-connect them one at a time.  If the first speaker doesn't play, disconnect it and connect a different speaker.  If the first speaker plays, connect a second speaker until you find the one that causes the head unit to shut down.  (If none of the speakers will play individually, then your head unit probably has a defective amplifier).

Hope this helps!

Brian