well I'm stumped and really need some help. I have a 2001 GT conv. with mach 460 audio. I wanted to replace just the head unit and continue using factory amps and speakers.
I purchased an alpine 9856 head unit so I could have mp3/ipod/xm radio. I know the mach 460 has 8 speakers; 4 tweeters, and 4 "subs". One amp powers the tweeters, one powers left subs, one powers right subs.
I purchased a metra harness to do the install, here:
http://www.partsexpress.com/pe/psho...FTOKEN=43190980
It comes in 2 pieces, one piece is for power, ground, the 4 speaker connections....the other piece is supposed to be for the amps. the 2nd piece of the harness has 4 wires; 2 for amp turn on and 2 grounds.
I wired everything up and I am only getting sound from the 4 tweeters. it seems the sub amps are not turning on or something I don't know what I'm doing wrong. I've read the manual 5 times, I've tried every possible option on the radio from subwoofer off to power IC off / on. I read the article on stangnet about this as well. My HU has 3 pair of RCA outs, labeled front/rear/sw ... the harness has only one pair of RCA's so I'm not sure which pair on the HU to plug into either. In the Alpine manual it says if you are connected to external amplifiers than you should turn off the internal HU amplifier by turning a setting called "power IC" to "off" . When I do that, I get no sound at all. When I leave that setting on, and it uses the internal HU amp apparantly, the 4 tweeters work great, but I have no sound coming from any of the 4 5x7's .
I wired all speaker wires, grounds, and power from the radio harness into the metra harness. I wired the 2 amp turn on wires from the 2nd piece of the metra harness to remote turn on on the head unit harness. Any help would be really appreciated I'm frustrated been playing with this for 3 days now
2001 Mach 460 New HU -- No Bass 
