I originally posted this on NAGCA but no one seemed to take any interest in it. It really is a great mod though. It still works and sounds great.
In this how-to I will be explaining how to play music from your iPhone, iPod, or MP3 player through your radio without:
(a) buying a new radio
(b) Buying a PAC adapter
(c) Using an fm transmitter
(d) Needing a cd changer
Your going to need a philips head screwdriver, soldering iron, and a 3.5 mm audio wire.
My dad did this to our Yukon XL a while back and I thought I would try to do it to a Chrysler radio. In the Yukon, the cassette was a slave so it was separate from the radio and didn't involve any soldering. This was going to be different. My radio, from a 2001 WJ with the Infinity 6 speaker system, has the cassette in the head unit.
I started out by taking the radio out of the car (duh). After you take it out grab a towel and go sit at the table with a philips head screwdriver. On the back at the top there are two screws holding on the top cover, remove these. Using your fingers, pry the cover off the top of the radio. Its a bit difficult but you can do it. If you use a screwdriver, you risk bending the metal. After that, look around the front of the radio on the plastic. There should be four screws holding it on and they need to be removed. Pull off the volume knob and place it to the side. Then, pull on the face of the radio undoing the little clips on the top and bottom.
Once you get it off, you may notice there aren't any screws holding on the front board. It is held on by two little ground tabs that need to be unsoldered and twisted straight. After you do that pull up on the board CAREFULLY. Place it to the side. Next, were going to remove the cd player. My cd player had three screws on top and one on the front behind the board we just removed. After that, pull up on the cd player by its edges and place it aside. Under the player you will see a few rows of solder. You need to find the one in the back running parallel with the casing. Here is where the hard soldering comes in. Find the three pins labeled l-ch, r-ch and the last one under them. I cannot remember what it is labeled. It is the audio signal ground. Just look at the picture. Strip your 3.5 mm wire and seperate the shielding from the wire. DO NOT cut the shielding. It is the audio ground and your third wire. Strip the two smaller wires and twist all three. BEFORE YOU START SOLDERING PUT THE WIRE THROUGH THE RADIO CASE. Solder the red wire to R-ch, the white wire to L-ch and the bare wire to the third pin. Make sure your wiring and solder do not touch other wires and pins. That will cause a short. If you don't trust your solder to hold you can also throw a bit of hot glue on there.
If you want to, you can get an audio jack from radio shack and put it in the front of the unit. I didn't do it because there is already not enough room for whats there so I don't think it would be easy.
Now start putting it back together. Cd player first, then the front board. When your screwing the cd player in it will squish the wires so don't worry about the wire being too thick. Make sure the solder gets put back on that front board or else it wont have a ground anymore. Pop the front plastic back on and the top cover and screw them in.
To make this work you can play any cassette tape. when you plug anything in it just mutes the tape player. I suggest getting a tape adapter and ripping of the wire because those tapes always spin so you don't have to flip them or rewind them. If you do use a regular tape, when the tape reaches the end it reverses and the sound stops for like half of a second.
This mod is amazing. Where I tapped in, the equalizer, fade and balance all work and the quality is great. It sounds better than a cd.
Now it's your turn to choose what to do with the wire depending on what car this is going in. On my WJ I ran it to a little radio shack 3.5 mm audio jack that I put in the top of the ash tray. You could also run the cord down to the ash tray and just pull it out when you need it if you want. Whatever you want. If a 15 year old can do it so can you