I come across this problem at work every now and again.. I believe the problem is this... from the factory the wiring from the ground wire from the battery to the frame is pretty cheap, and start turning blue and corroded.. not only at the battery but the complete wire itself.. this tends to happen alot when upgrading your system in your car adding amps and subs.. general rule of thumb is the ground wire from the battery to the frame has to be the same gauge wiring as from the power wire to your amp.. now I dont know if you have a system, Im just letting you know what generally causes this issue at my job... now there are two types of cable the cheapy choppy wiring from walmart.. that says its 4 gauge and its more like 6 gauge with thicker rubber insulator that is junk ..reason why its junk is because when the wire is made, the company did not do a process which removes all of the oxygen from the copper.. and that right there is the reason why your wiring turns blue with the corrosion and doesnt perform as it should.. then you have the better wiring, for example kicker wiring or something from a name brand audio company that removes the oxygen from the wire and does not turn blue or lose its strength over time.. back to your issue, I believe if you change the ground wire from the battery to the frame, your problem will be solved, it being from the "cheapy choppy" category, Im almost certain it has lost its strength and cant handle the amperage it once did .
