I searched and searched for info on changing the radio before tackling my project, but found little info. For the next guy, here's what I did:

Since I installed a single din radio I had to order a trim kit online, check Ebay for the best prices. You will also need an antenna adapter. I found a wiring diagram easily by googling "Chrysler Pacifica radio wiring diagram" and printed it out. The radio comes out pretty easily. Unsnap the trim around the ignition and the silver trim around the shifter. Pull up on the rest of the center console around the shifter and it snaps right off. You will need to turn the key and put the shifter out of the park position to do this. Do the same with both pieces on the sides of the radio/climate control, they snap right off. This exposes the 4 screws holding the radio in, remove them. Pull out on the radio and disconnect both harnesses and the antenna.

My car had the stock amp behind the last seat row on the right, so I wasn't able to use the speaker wires going to the original radio. If you try to do this you won't get any sound. There are adaptors available to let you keep the existing amp, but they are like $150. I didn't want to use the amp, anyway, because the stock system sounded lousy and I didn't want any part of it to remain. I took out the amp and ran speaker wires for all 4 speakers from the new radio to the location of the old amp. I routed the wires behind the glove box and under the floor moulding all the way back. You don't have to remove anything, just get something to pry the moulding up from the carpet a hair and shove the wires in. Remember to label the wires before you start routing them!

Once the wires are at the old amp location, follow your wiring diagram and snip and strip the wires from the amp harness that go to the speakers. Connect your new wires to the existing speaker wires. If you want to install a new amp you can also use the existing amp turn on wire from the second, smaller amp harness. This wire is the same color at the radio harness, so make sure you hook it up at that end, too.

Following your wiring diagram again, snip and strip the power, accessory, and ground wires from your old radio harness, and connect to the new radio. Hook up your antenna adaptor. I found out you do need power to the antenna turn on lead to get reception, so follow the wiring diagram and snip, strip, and connect it to either accessory power or the amp turn on for your new radio. Mount the radio in the single din adaptor you bought, install the adaptor, and snap everything back together.

If you want to run battery power for a new amp, I found a spare hole through the firewall on the passenger side, just about where the carpet stops. I pulled the grommet, poked a hole in it for the 12 gauge hook up wire, fed the wire through, and reinstalled the grommet. Remember not to run your amp power wire beside the speaker wires or RCA cable, you don't want them to pick up any of that nasty car power noise.

The questions I wanted answers to before I started, but eventually figured out myself:

Can I just buy a wiring harness for my car and snap it into the existing radio wiring? No, not if you have the stock amp. There is one available that has RCA cables instead of speaker wires, enabling you to send the pre-amp signal from your new deck to the existing amp, but you will loose all fade and balance control.

Can I hook my new radio speaker outputs to the existing wiring running back to the amp, then just jump the amp to the wires heading to the speakers? No, you will not find corresponding speaker wires behind the radio. The amp is part of the brain of the system, splits the signal for all the speakers, and controls the fade and balance. You either need to run new wires to the speakers, or run them from the new deck to the amp location and tap in there.

I put in a Pioneer deck and Infinity Kappa speakers in all the doors, components in the front, of course. The Infinity components came with a couple of choices for the tweeter mount, and one of them fit like a glove in the old tweeters spot. I had to drill my own screw holes in the doors, but other than that the speakers went right in. I don't have my sub hooked up yet, but it already sounds 10 times better than stock!

 

I am about to install an aftermarket radio in my wife's '04 and was researching. I have a question with this. Why arent you just able to hook into the stock radio wires that head to the stock amp, usually the head unit is the part that controls everything. It just sends a signal to the amplifier. the amplifier is just as it is called. All it is supposed to do is amplify the sound from the radio unit. It isnt supposed to do anything else. My wifes car only has the radio/cd player, no nav, no cd changer. Just basic. So if you take the aftermarket radio remote wire and hook it to the amps trigger wire then it should work.

 

You can't use the existing speaker wires from the stock deck to the amp because the amp is part of the brain. There are no front left, front right, etc wires coming from the stock deck. The amp takes the signal from the deck and separates it into the right, left, front, back channels.

 

Where is the factory amp.

 

I found it, it was under the storage compartment in the rear hatch area on the right side. Thanks guys the info I got from this site was very useful.

 

Well I have a 2000 Chrysler town and country, and I got the infinity amp to work by hooking up the new radio's ground lead, the single ground lead and the ground strap ribbon together, as well as the antenna wire lead from the new radio to the las lead on the black connector opposite the small keying tang, hope that helps

 

run into another problem; no cd sound, but I found this answer which means the antenna wire goes dead during cd playback.
"If there is no sound or the amplifier turns off when playing a CD, but there is sound and the amplifier is on when playing the radio, then you may have the solid blue (antenna remote lead - ANT REM) and blue striped (amplifier remote lead - AMP REM) wires connected incorrectly. Try switching these wire connections.

In vehicles designed to supply power to the amplifier through the antenna power supply, connect the solid blue antenna wire to the solid red ignition wire. In all other vehicles, connect the blue and white amplifier turn-on wire to the solid red ignition wire.

Use of the antenna remote connection to the amplifier is not recommended since a no sound issue will occur when playing a CD. "

 

I recently installed a dual brand deck in my van everything works fine but i cant seem to figure out how to hook up an extra round wire behind the deck i think its the antenna wire because i have no radio fm or am but everything else works any ideas