-Did you use an amplifier integration kit that retains the factory amps or did you bypass?
-When you ran your 4 channel directly to the factory connection in the dash where did you connect it your 8 wires?
-After you connected the 8 wires, how did the unamplifed signal get to the the speakers without going through the factory amplifiers?
-When connecting the 8 wires to the factory connection is there any way that the signal will get to the 5x7's without the factory amplifiers?
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In the Mach 460 system in the 2004 Mustangs, there are TWO amplifiers, both mounted on the rear speaker pod. One of the amplifiers powers the front "woofers" and the other powers the rear "woofers" All 4 tweeters are powered by the internal amplifier of the stock radio. In my 2003 Cobra I gutted ALL factory components, (radio, speakers, amps, rear speaker pod).
I do not recommend using the new CD palyer to run the tweeters. It would help me to know exactly what Infinity reference speakers you are using, (coaxials, component set, actual part #'s) The factory tweeters have no crossovers or bass blockers on them so if you run the Kenwood deck internal amp to them they will distort at a very low volume. If you use only the new Infinity speakers and the new 4 channel amp you will get the best possible sound.
When installing a new deck into the car you will need a harness that plugs into the factory radio plug. (Metra part # 70-5520) This harness is wired to the harness that comes with the new radio that you are installing. The only wires that you will need to connect are as follows: Yellow (12 volts constant), Red (12 volts switched), Black (ground). On the Metra harness you will have 8 speaker wires (white, white/black, gray, gray/black, green, green/black, purple, purple/black). These are the 8 speaker wires that you will connect to the 8 speaker wires that you will run from the AFTERMARKET 4 channel amp. Here is a picture of the metra harness.
View attachment 330701
Here are two basic diagrams that I drew up, both show the same thing but one might be easier to understand. This is only showing the speaker wires and the yellow, red, black wires needed to hook up the new CD player. There will be more wires on the Metra plug but they are not needed to complete this install.
You will also need to run 2 pairs of RCA cables and the remote turn on wire (blue with white stripe) from the new radio to the amplifier. Here is a basic diagram of that.
Remember that when installing your new speakers the you MUST hook them up to the factory wires that were connected to the stock tweeters or you will have no sound.
To answer your final question, the only way to get signal to the wires that go directly to the factory 5x7's you would need to splice into the harnesses that are plugged into the two factory amplifiers in the trunk of the car. I do not recommend this as it is a lot more work than doing the method I use.
I didn't mention and you may already know but you will need a dash kit to install the rew radio. It is Metra part # 99-5026. Here is a picture.
Here are a few tips that may make the install go smoother and sound better when completed.
Run your 2 pairs of RCAs, remote turn on wire, and 4 pairs of speaker wires together from the radio location down the passenger side of the vehicle to the area that you are mounting the new amplifier. (I installed mine on the back of the rear seat). I use 5 meter RCA cables and leave about 12" of excess length in the dash so it is easier to plug everything in before you mount the new radio.
Use a good quality amp power kit (Streetwires, Kicker, JL Audio, Stinger). Also don't go cheap on the RCA's, it actually does make a noticeable difference. Depending on the size of the amplifier, I always use at least 8 guage power wire.
Run the power wire from the battery through the firewall down the drivers side of the vehicle to the amp location. You MUST have a fuse usually within 12" of the battery, and I always leave excess power wire coiled up under the rear seat so if I ever move the amp to a different location further from the battery I won't have to re-run a longer cable. Also you should never run the power wire next to RCA cables, as this can cause unwanted noise in the system. Here is a picture of where I drilled a hole in my firewall for my power cable. Pic is taken from the inside.
The ground cable MUST be of the same size as the power cable, and should be kept as short as possible. When choosing a grounding spot, make sure to scrape the paint away from the area that the ring terminal will be touching. I used one of the large bolts that holds the seatbelt under the rear seat.
I have been a MECP certified installer for 11 years and this is how I do 90% of my amp installs, and this is how I do ALL of them in the Mustangs that have the newer Mach 460 system. If you have any additional questions just ask, I will check here again tomorrow.
