04 bmw x3 audio wires

does anyone know what each of the main 16 wires for the audio system are. Its an 04 x3 non nav/non dsp with factory amp. 8 i know are for the speaker outputs to the factory amp, the rest are not as clear. I am constructing my own wiring harness for an aftermarket stereo while trying to maintain function of the factory amp. I am assuming that the other 2 sets of connections to the factory system are the aux in and steering wheel controls. if I am wrong in this please notify me thanks for the help chris

awesome that only leaves 2 more wired to id. also what does the acessory wire do?

The accessory wire is what turns the radio on and off with the key.  Key off = no voltage on said wire.  Key in acc or on position = 12 volts on said wire.

ok that makes sense. This vehicle had the option of blue tooth and has an sos call button, neither of which i will be using could one of the additional wire be for this? I have also read else where that the factory amp has a ground connected to the radio...black wire. there is a smaller black wire what do you think? or would it be for the speed controlled volume. i will get the other wires colors maybe this will help

one wire is WHITE/ red stripe and has yellow marks down the visible length, the other is gray/red stripe, and the thin black wire

that is the harness i bought 2 of, 1 to use and the other to take pins out of to engage the factory amp. i just want to ensure every wire is correct before i plug it in.

There should be a wire on the harness that turns the amp on.  Have you checked the white wire of the factory harness to see if it has a mating wire in the harness you purchased?  It should be blue or blue/white.

i bought the metra 70-9003 it has power, ground, constant, and power ant. that is why i bought 2, the second is to add pins for amp turn on and illumination. im not sure what the other wires are but i hope running without them wont throw up error codes, which is why im pestering yall so much. thanks for all the help