Need some help figuring out a few problems on '98 EB expedition with mach audio head

[logoster]

Hi, so as the subject says,I'm installing a new head unit in a '98 expedition EB with the mach audio system, and I've run into a few problems

#1 and the one I want to fix first: the head unit will not power on UNLESS I touch a pair of speaker wires from the head units harness to the accessory power wire, at which point it powers up instantly and stays on until I stop holding the speaker wire pair to the accessory power, I'd really like to figure this one out (pic of how the head unit harness is wired to the aftermarket harness: Imgur: The most awesome images on the Internet (the accessory power wire is wired with that cap for ease of taking apart since that's the one we need access to to test the head unit being we can only get it on through the method of problem #1))

Problem #2: 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?

And third problem which is also sort of a question: what are the extra wires in back that don't reach the front for?(pic at bottom) going by the crutchfield diagram it's the speaker wires coming from the amp to the speakers (1997-1998 Ford Expedition with Mach Audio Wiring Information look at 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)

Thanks any help is appreciated

Oh, and the head unit is a Sony cdx-g3150up

[logoster]

Anyone? I'd at least like some help figuring out the first issue, I can likely figure the rest out on my own after that since the first issue likely makes it not so easy to test and fix the others

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[Chris from Washington]

Hi,
Welcome to the forum.

Wow something is really not right there, or I didn't read it right.

So you're saying the head unit will power up, if you apply 12V to the speaker wires off the harness? Something like that would normally fry a deck pretty quick.

I think we need to do some testing out of the car. Do you have a way for testing hook the deck up directly to a battery or other power supply?
Does it power up this way by hooking up the correct wires to 12V?

[logoster]

If I hook everything up correctly it will not power on, however if I touch both the positive and negative of say the front left speaker wire from the head units harness to the accessory wire while it's hooked up (so the radio would also still have its accessory wire hooked up to the car as well, I'm not connecting just the speaker wire to the accessory) then it will power on instantly (and has no problem running like that either, I can have the antenna hooked up and it seems to recieve it fine as after a few moments it will display the station and song info, no idea how good the sound is yet though)

And no, I don't have a way to hook the unit directly to the battery

My assumption would be a circuit somewhere not being completed

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[logoster]

Hi,
Welcome to the forum.

Wow something is really not right there, or I didn't read it right.

So you're saying the head unit will power up, if you apply 12V to the speaker wires off the harness? Something like that would normally fry a deck pretty quick.

I think we need to do some testing out of the car. Do you have a way for testing hook the deck up directly to a battery or other power supply?
Does it power up this way by hooking up the correct wires to 12V?

hey, so i've had a chance to test it via the battery method (twisting accessory and constant power wires together on radio harness, then holding that to positive terminal on car battery, and ground to negative terminal on car battery) and the radio came on no problem, so i assume the problem is with the dash wiring or the aftermarket harness, in which case, what would be a good harness to buy for my vehicle (only factory harness that's still there is the power harness, whoever previously owned the vehicle for whatever reason decided to cut off the speaker harness, so speakers are just wires atm) as the aftermarket harness i've been using is the one that the previous owner left sitting in the dash hooked up to the factory harness (also if there's a better name for these to make what i'm saying better to understand that'd be great) so i'd like to hope that since the problem isn't on the head units side that the aftermarket harness is the problem being that that's much much cheaper to replace then the factory wiring, and i can replace it on my own, also unlike the factory wiring.

[Chris from Washington]

hey, so i've had a chance to test it via the battery method (twisting accessory and constant power wires together on radio harness, then holding that to positive terminal on car battery, and ground to negative terminal on car battery) and the radio came on no problem, so i assume the problem is with the dash wiring or the aftermarket harness, in which case, what would be a good harness to buy for my vehicle (only factory harness that's still there is the power harness, whoever previously owned the vehicle for whatever reason decided to cut off the speaker harness, so speakers are just wires atm) as the aftermarket harness i've been using is the one that the previous owner left sitting in the dash hooked up to the factory harness (also if there's a better name for these to make what i'm saying better to understand that'd be great) so i'd like to hope that since the problem isn't on the head units side that the aftermarket harness is the problem being that that's much much cheaper to replace then the factory wiring, and i can replace it on my own, also unlike the factory wiring.

Check outMetra and see if they have a harness that will work.

Metra also has harnesses meant for the factory stereo. so you could always also get one of those. Splice that in to fix the cut wires/missing harness.

Then get the aftermarket harness that will plug into the harness above, that way everything is connected nice and neat.

That should fix everything.

[logoster]

What part numbers for the factory harnesses would you recommend for my specific vehicle if I end up having to go that route?

As the harness that provides power and such to the factory radio is still physically there and all the wires appear to be hooked up right, it's the speaker harness that was cut off, so for now I'd like to assume it's just the aftermarket harness that converts the factory radio connector to color coded wires

Also, if it does end up being the aftermarket harness(getting a multimeter today to test the dash wiring?, which part number would you recommend for that? As there seem to be multiple for a '98 expedition and I can't really tell which one I'd need

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[Chris from Washington]

I think this is the kit you need, it comes with both power and speaker harness.
Metra Part # 70-5600 | Ford wire harness | Metra Online

and this is the factory one that would have connected to the factory radio
Metra Part # 71-5600 | Ford wire harness | Metra Online

It comes with both.

but you could just get the aftermarket ones. Plug the one into the power harness, then connect the wires to the deck (verify you have them all matched up right. Then see if it works properly.

From there you could either, just hook the speakers directly up to the cut wires. Or purchase the factory speaker harness, and then do the same that you did with the power wires.

[logoster]

So good news, the wires were fine as was the harness, turns out the problem was the fuse for constant 12 volt was deader then dead, and the previous owner tried to "fix" it by wrapping some copper wire around the fuse prongs

Yeah so we replaced the constant power fuse (as well as the accessory 12 volt fuse for the radio as at some point in messing around with it all it also died) and then wired the radio harness back to the aftermarket harness, plugged it into the factory harness and it booted up first try, heck, even before we turned on accessory power something in the head unit spun up (I assume the cd player checking for a cd) so next project is wiring the speakers to the radio harness (which isn't going to be fun as the previous owner bypassed the factory amp, which isn't a big problem until we discovered that the bypass wires are the ones way in the back bottom that don't come even close to reaching the front of the dash)

Although I'm still confused why touching a speaker wire on the radios harness to accessory power made it power up when the problem was constant power being dead

Anyway, thanks for helping, sorry for wasting your time over something I probably should have checked the moment the head unit didn't want to boot up

Although still curious over what that capped off blue cable is, all I know is it appears to be running into the engine bay through the firewall, can't really tell for sure though as it's mostly behind the dash

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