Ok, first off yes only one plug plugs into the headunit harness wise. And the other plug that goes to the amp is the only other plug you need. The additional plug is for the 10 disc cd changer. Do you have that amp plugged in under the seat? Did you check your fuses under the hood? If neither is working I think you should check with dsmmyth, he actually succesfully got the Infinity system working in his car, but with an aftermarket amp. I tried this awhile back but gave up for aftermarket again. Anyways, look over what I said and if that doesnt help PM dsmmyth.