This is the 3 mini iso harness that plugs in the back of the oem alpine. I know the majority of posts are about adding iPod/mp3/iphone inputs into the head unit.
I am working on installing the Pioneer 4000NEX, DVD player, this unit has dual zone feature, allowing the back seat passengers to watch a movie(headrest monitors) while driver can use carplay/appradio/navi. This feature has separate audio that is sent to headphone jack via 3.5 on back of head unit. My plan is to make use of the installed headphone amp already in the Disco. The yellow mini iso goes to the headphone amp. I have been searching for a yellow male mini iso that i can just plug into the yellow oem plug(don't want to cut the oem wires), but all are in Europe.
From what I have read, the headphone amp/jack in the Disco, when hooked up to oem stereo, is capable of volume control, track forward/reverse and mode change. I am only wanting to make use of the volume control, understanding the track and mode switches will not be available. The headphone amp is activated by the same wire that turns on the amp under the seat. Is there is anyone who can shed some light on which wires in the above harness are left/right channels, the ground and the power. Out of the six wires, I am assuming four are for left and right channels, and the other two power and ground. my plan is to use a 3.5 to rca input adapter, cut off the rca plugs, plug into phone and experiment with the holes to determine the left and right speakers(have a small computer speaker setup to plug into headphone jack). After determining the speakers, checking continuity on two remaining plugs for ground, hopefully leaving the last one to hook up to the blue amp turn on wire from the head unit.
Any insight would be greatly appreciated.

 

From what i have learned, the blue mini iso, is for cd under passenger seat, the green and the yellow is the headphone amp. in the pic CO921, CO922 are the ones that i need to hook up

 

update, the metro 70-1787 has the 20 pin male harness I need, so it is off to Best Buy. I already have the black part (metro 70-1786)



the mini iso oem plugs into the red part of the above kit.

 

Your a brave man. I couldn't get this to work last time I messed with it.

Have you tried the RAVE electrical library. It is a companion document to the Rave Electrical Diagram document.

I have both if you need it.

Please, if you get it working, post a update with kit model numbers, pin outs that you had to splice to, etc.

I just got finished mapping out the power amplifier in/out, and had to use the library document to figure out which speaker leads were + and -

 

I have the manuals and have been combing thru all of them. I have the left/right speaker inputs down, they are on the yellow plug. The metro kit, has 4 RCA plugs, and I only need two of them, 1 for left and 1 for right, so I will re-pin that connector to match the oem, and the rca's will connect to my 3.5 to rca adapter that plugs in the head unit.
Now deciphering which pin will activate the headphone amp, is next. The description on the charts are not clear to me, There are two pins on the yellow connector that say telephone input, telephone output. then there are two pins on the green connector that say "audio amplifier spatial imaging enable", the other says "headphone remote control feed" both are listed as output, which means output from head unit to headphone amp. one of these has to be hooked up to the same wire that turns on the amp, and antenna booster(as per manual)
The metro kit will be in my hands tomorrow after work, and once i re-pin that one, i can hook up and experiment with powering up headphone amp. I also wonder if these need 12 volt power in addition to the signal from the amp turn on wire,(like regular amp), or it only uses power from the turn on wire.

 

Finished repinning the mini-ISO,hooked up my iPhone and viola, music from my headphone jacks. Now my harness is complete, steering wheel controller programmed. Next, Remove the cd changer, install my mono-bloc amp in its place along with digital tv tuner, run my Hdmi cable and one of my 2 usb cables(for 480gb intel ssd full of flac audio files and MP3 files, 300gb of ripped dvd's)to glove box. Run 2nd usb cable to console for iphone(CarPlay). Run sub rca and tuner rca leads, blue wire(sub) and switched power(tuner) to passenger seat. Run digital TV-tuner antenna to roof. Install SiriusXM and navi add-on under dash(somewhere), run antennas(both) to top of dash(gps) and roof (xm). Install video splitter under console for headrest monitors then rca video lead to head unit. Install rear view camera and run video lead to head unit. Run audio/video leads(aux) to console compartment ready for android mini-pc stick, lastly(I hope) install 2din head unit in that big hole in my dash. I have to do all the above first, because I do not want to pull it out again. A lot of wiring, but the end result will be a nice media center,

 

Sounding good. please don't forget to document what wires you hooked what up to. If possible, try to include the connector name, the pinout, and the wire color.

This is awesome. Someone finally taking the plunge and figuring it out is going to open alot of possibilities!

Nice work!

 

update on rear headphone amp
I got it all installed and the rear headphones are working just as I wanted. The only controls that work are the volume up and down, just like i wanted.
The yellow mini-iso plug is the one going to the rear headphone amp, and you use four of the six pins, the two middle pins are not used, they communicate with the oem head and will not work with aftermarket stereo. the other four are left channel pos, left channel neg, right channel pos and right channel neg. When you turn on your aftermarket head unit, and you have wired correctly(amp turn on wire) it powers on the headphone amp. I hooked up headphones and it did increase and decrease the volume.
Cybercop, my second post on this thread shows the pinout for the headphone, and the metro 70-1787 was perfect for the job. Now on my head unit, i do have dual zone, so these were hooked up to the second zone, perfect for my setup. Now for some aftermarket stereos, you would have to get a splitter for say the front two channels on a 4 channel head unit, so you can have a signal going to the speakers and going to the headphone.