03 Grand am Sub installation

To get a signal to the amp you will need a high to low converter http://www.pac-audio.com/products/loc.htm. The high to low converter will tap into both of your rear speakers (must tap in after the amp, I would tap in near the speaker its self). This will give you an rca input for your amp. As far as the power goes there are 3 power wires you will need to connect (power ground and remote) I would suggest you get an amp kit http://www.knukonceptz.com/detail.asp?product_id=KOLAK8 this will give you all wires and fuses that you will need to wire your amp including the rca cable. You will hook up your main power wire to the + side of the battery (You must install a fuse within 18 inches of the battery. That is what the fuse and fuse holder in the amp kit is for) and connect the cable to the + power connection on your amp. For the ground wire it must be no longer then 18 inches long. You will want to find a good metal surface in your trunk. Sand it down to bare clean metal and attach it to the clean surface. You will then attach the other end to the - or ground connection on your amp. For the remote turn on wire which will turn the amp on and off with the car. You will need to find a switched 12volt source. I normally tap into the ignition harness. You will want to tap into the pink wire, but always double check it with a voltage meter. It should have + 12 volts with the ignition on and no voltage with the ignition off. You will then connect that wire to the remote connection on your amp. When running all your cables you will want to keep your signal (speaker wire rca etc.) as far apart from you power (power, ground, and remote wire) as possible to avoid any interference. Once you get everything hooked up you will need to adjust your gains https://incolor.inebraska.com/weisinator/car-audio-basics/set_amp_gains.htm and set the x-overs on the amp. If you give me the model # of you amp I will tell you how to adjust it. But I normally set any sub sonic filter as low as it will go and set the low pass filter to 80Hz. Here is a tutorial on how to install an amp http://www.crutchfieldadvisor.com/learningcenter/car/S-Ujue25bhdNH/amplifiers_install_steps.html