Hi guys, so as you probably know with my first post talking about it, as well as my other rage induced post (which turned out to be kind of incorrect) i'm installing a new head unit in my family's '98 expedition EB with the mach audio system, however, we've run into a few problems: to make sure power was working we wired the radio's harness to the aftermarket harness that was already there (my guess is previous owner had an aftermarket head unit as well) however, it didn't power on, at least not until a positive and negative speaker wire on the head unit's harness was also touching the accessory wire at which point the unit powered up instantly, so what's that about? (radio-aftermarket harness wiring pic: http://imgur.com/a/99Ujq first pic is an overview pic, second is the power wires (blue is the AMP turn on wire)) second problem: the speakers don't seem to be working, we tried connecting speaker wires from the head unit's harness to the plain wires sitting in the dash (the main speaker wires according to a Crutchfield diagram I found online for the '98 with mach audio) and hooked up the fm/am antenna to test with(which does work, as the info of the station and the song that was playing showed up on the display of the head unit, so we have signal at least) and nothing came out of the speakers, not even static. Now I've read up on this and apparently it has something to do with the factory amp not turning on? What's a way I can test this easily? third question: what are the extra wires in back that don't reach the front for? going by the crutchfield diagram it's the speaker wires coming from the amp to the speakers (http://crutchfield.custhelp.com/app...2LzEvdGltZS8xNDc0NTkxNzAxL3NpZC9Gd3JTWWlfbQ== amp wiring, the non-input labeled ones) but the amp is most definitely there, i can see it hidden under the dash, could that possible be that whoever owned it previously bypassed the amp? in which case how would i test those wires to see if it indeed an amp bypass, as it's not possible for me to wire it to the speaker wires on the harness that easily since they're way in back and bottom of the dash and can't be pulled up front (as you can see in this picture: http://i.imgur.com/11AQVGO.jpg ) And last question, there's a random lightish blue wire that reaches all the way to the center console storage, it's been crimped off it appears but what would it likely be or have been for? (i've traced it somewhat, it appears to be going into the engine bay, can't tell for certain though, will get a picture of that aspect later, for now you can see it here hanging in the front of the dash right under what's supposed to be the speaker wires that go TO the amp from the head unit going by the crutchfield diagram: http://i.imgur.com/11AQVGO.jpg) any help is appreciated, as it'd be nice to do this myself, especially being that everyone seems to say that the expedition is insanely easy to install a head unit on
