i have a question. ive read the faq but it doesnt deal with what im looking for. up until now, ive been using the metra harness for a saturn, metra 70-2002. whenever i change stations, change cds, turn off the car, etc. a loud humming noise comes from the rear speakers. i bought the gm wiring harness and noticed that the grounds are in the same position (this is what i thought the cause was) but the amp turn on/off wires were in a diff position. could this be the problem?