Replacing the replacement of the Mach 460 system

Pikatwo · Jun 23, 2024

I recently inherited a neglected ‘94 GT convertible with a Mach system. A previous owner had installed an Alpine aftermarket head unit so my first thought was to replace it with an original Mach stereo/CD combo - all my Mustangs have been as stock as possible.

However . . . after reading about all the problems with the 30-year-old Mach setup I’ve realized it might be better/easier to get a completely new system. I have a Pioneer EVH double-din that’s a few years old but it’s a great unit (and has Bluetooth), so I ordered a Metra replacement dash kit and will use that.

Since my hearing is not as good as it used to be (and this will mostly be driven with the top down) I really don’t need an impressive system. With that in mind, these are my actual questions:

1. Is it better/easier to pull all three old amps (the front is already disconnected) and wire the Pioneer unit directly to new replacement speakers? Or should I disconnect the old amps, get a new one, and use the existing speaker wiring?

2. Since a Metra harness for the Alpine is already attached to the stock wiring harness can I re-use that? I do have an extra stock 460 harness in great shape in case I need to attach a new Metra harness for the Pioneer.

Any help would be greatly appreciated, and sorry for the length of the post. I do go on…

ttocs · Jun 23, 2024

Ditch the amps, use the wiring but with a twist/trick. Get a 70-1770 wire harness if you do not want to cut any wiring. Now the only difference you will find between the harness already in your car and this harness is the speaker side of it and if you are comfortable cutting/using the harness that is already in the car, that will not be used once you bypass the amps you can save a few bucks.

When you pull the radio out, look inside the radio hole on the passenger side (towards the side of the glove box) and you will see a black 8 pin harness attached to the dash, plugged into another harness. That harness goes directly from the front amp, to the tweeter locations on the mach system and if you have a standard radio(non-mach) it uses this harness as its speaker harness. It will look almost like the power harness but it is all black, again 8 pins. If you want to confirm it is right you can power up the radio, then disconnect that harness and the tweeter should lose sound. Again you will not be using that harness so if you were to cut the male side off of the stock side with 6" of wire on it, the speaker wires are just +/- from one side to the other. You can again test which wires go to what speaker by stripping a little bit of the wire and then touching a AA battery side to one wire, the other side to the other wire and the speaker connected to it should make a popping noise.

So no matter if you buy the 1770 hrns or cut the stocker, wire the decks speaker outputs to that harness. Now you will need to replace the speakers, the radio does not like the stock system with its strange resistance and they are long since worn out by now. When you install the new speakers you will find two sets of speakers wires in each location as one is for the woofer, one for the tweeter. Use the harness that goes to the tweeters to connect your speakers and you have bypassed the amps. The other option is to run new speaker wires to each location but I can tell ya getting wire through the door is not that much fun.

shovel · Jun 23, 2024

Remove the amps, including the one under the radio. The harness that the amp under the radio connects to has the same connector on both sides so you can cleanly remove it and the tiny harnesses it's tied to (no point having dark wires along for the ride) . The radio speaker outputs will then directly connect to the tweeter wiring in the doors and rear. Then you can connect that wiring to the input of your component speaker crossover (it supplies signal to the woofer too now).

Pikatwo · Thursday at 6:57 PM

ttocs said:
Ditch the amps, use the wiring but with a twist/trick. Get a 70-1770 wire harness if you do not want to cut any wiring. Now the only difference you will find between the harness already in your car and this harness is the speaker side of it and if you are comfortable cutting/using the harness that is already in the car, that will not be used once you bypass the amps you can save a few bucks.

When you pull the radio out, look inside the radio hole on the passenger side (towards the side of the glove box) and you will see a black 8 pin harness attached to the dash, plugged into another harness. That harness goes directly from the front amp, to the tweeter locations on the mach system and if you have a standard radio(non-mach) it uses this harness as its speaker harness. It will look almost like the power harness but it is all black, again 8 pins. If you want to confirm it is right you can power up the radio, then disconnect that harness and the tweeter should lose sound. Again you will not be using that harness so if you were to cut the male side off of the stock side with 6" of wire on it, the speaker wires are just +/- from one side to the other. You can again test which wires go to what speaker by stripping a little bit of the wire and then touching a AA battery side to one wire, the other side to the other wire and the speaker connected to it should make a popping noise.

So no matter if you buy the 1770 hrns or cut the stocker, wire the decks speaker outputs to that harness. Now you will need to replace the speakers, the radio does not like the stock system with its strange resistance and they are long since worn out by now. When you install the new speakers you will find two sets of speakers wires in each location as one is for the woofer, one for the tweeter. Use the harness that goes to the tweeters to connect your speakers and you have bypassed the amps. The other option is to run new speaker wires to each location but I can tell ya getting wire through the door is not that much fun.

Pikatwo said:
I recently inherited a neglected ‘94 GT convertible with a Mach system. A previous owner had installed an Alpine aftermarket head unit so my first thought was to replace it with an original Mach stereo/CD combo - all my Mustangs have been as stock as possible.

However . . . after reading about all the problems with the 30-year-old Mach setup I’ve realized it might be better/easier to get a completely new system. I have a Pioneer EVH double-din that’s a few years old but it’s a great unit (and has Bluetooth), so I ordered a Metra replacement dash kit and will use that.

Since my hearing is not as good as it used to be (and this will mostly be driven with the top down) I really don’t need an impressive system. With that in mind, these are my actual questions:

1. Is it better/easier to pull all three old amps (the front is already disconnected) and wire the Pioneer unit directly to new replacement speakers? Or should I disconnect the old amps, get a new one, and use the existing speaker wiring?

2. Since a Metra harness for the Alpine is already attached to the stock wiring harness can I re-use that? I do have an extra stock 460 harness in great shape in case I need to attach a new Metra harness for the Pioneer.

Any help would be greatly appreciated, and sorry for the length of the post. I do go on…

Thank you for the help! I’ve removed the amps and installed new speakers but the original wiring harness is too butchered to reuse with the 70-1770. I have another uncut wiring harness in great shape but I’m wondering if I really need to remove the old harness since the other connections seem to be fine. Is it feasible to undo the loom and only use the section I need? I ended up running new speaker wires (since the new head unit accepts RCA inputs it seemed the path of least resistance) so I think all I really need is the wiring that carries power, ground, illumination and memory. Does that make sense or am I totally out in the weeds here? Photos of the portion I think I need to replace for reference.