Take your car to have a pro look at it, you can not properly diagnose a problem with a key board! Everyone is guessing about RCAs we dont know what the voltage is or the ohm load is, hell we dont even know what model of amp he has. Could be on a Hi-low could be aftermarket. My point is you need to have some basic skills and the proper tools to truly diagnose any problem in this industry. But first and foremost you need the CAR and I dont see one. At least 85% of the info I get from customers is wrong. You might get the right answer here you might end up doing more damage. Most shops will check this for free or cheap and you will know exactly.