Easier way of testing for a short than cutting wires is to back-probe the wires that run to the speakers. Do this by un-plugging the head unit, and then taking a DMM set to continuity check. Connect black lead to chassis ground, and then probe the speaker wires, colors are white, gray, violet and green. Each has a primary color and a black stripe wire, which is the negative. If the meter shows continuity then that is the speaker shorting. Vehicles wiring is probably OK if it is OEM and you have not changed anything. Chances are its a broke terminal on the speaker itself, that is loose and shorting out.
If you have exhausted all efforts, take the unit and wiring harness out, and call around to the local stereo shops to see if they can bench test it for you. Some do it free, and some charge a small fee, usually 10-20 bucks. This will finallize the troubleshooting and let you know if it is internal to the deck.
Sometimes the Firebirds have OEM Delco amps. The best way to verify this is to see if the blue remote wire from the decks harness is connected to the blue wire on the aftermarket adapter harness, this of course is assuming that it was not hacked off and hard wired. Either way, the amp wire would have been wired up by someone to get sound if it had an amp. Next best thing is to use a tone generator and try and tone the speakers without any power to the vehicle. If you have tone come through, then non amplified. No tone till the blue wire is energized, then its amped.
Note: You can also substitute the DMM with an LED test light. Not sure as to where to buy them other than from a tool dealer. I get mine from Snap-On and Matco.
Recomended Tools:
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