alright, not totally sure what you're asking, but here's an answer.

first, i've attached two pics, one of the metra harness on which you can see three holes with no connections. the other pic is the gray power harness that is connected to it. this is connector A in this: http://www.nexxia.co.uk/More_Information/ISO_wiring.htm

in the gray power A connector, here are the wires on 1, 2, and 3 which are not currently connected (these are the top left 3 in the picture):

1 = brown/orange
2 = black/grey
3 = red/grey

i think these wires are for the steering wheel controls, because when i look at the instructions for my PAC controller, its telling me to intercept that red/grey wire for the controller and use black/grey as a ground.

is that what you were asking?

p.s. i dont have connector "C", only A and B. A is gray, and B is brown.

 

you dont have 3 connectors?

ok another question do you still have your factory radio and if so does it work?

 

ok hold on, what wire is closest to the locking tab in the gray connector it would be pin 2 on connector A on this diagram, and is anything connected to it on the Metra side?, also what color wire is in pin 5 on connector A in that diagram?

 

Just to confirm, I'm cutting the brown/orange off the back of the connector, right?

One of the other diagrams says orange/brown is telephone, but not worried I don't have car phone.

 

no I was confused about your wire locations, reread my post

 

the wire on pin 5 in connector A is red and blue which is directly across from the blue/white wire in the Metra.

pin 2 is black/gray.

 

ok I think we are both looking at this backwards from each other, on the grey connector there is a release tab, the wire that is closest to it (which is pin 2 on this diagram http://www.nexxia.co.uk/More_Information/ISO_wiring.htm) lets try tapping the blue/white wire to this wire. you don't need to cut it just strip a small spot a few inches back from the harness and tap into it. make sure the volume is not all the way up.

 

hmm...i promise that wire on pin 2 (closest to tab) is black/grey = ground for steering wheel control.

here's how it goes:

1 - orange/brown, nothing on metra
2 - black/grey, nothing on metra
3 - red/grey, nothing on metra
4 - brown, to yellow on metra
5 - blue/red, to blue/white on metra
6 - red, to orange on metra
7 - brown/green, to red on metra
8 - black, to black on metra

 

connect to pin 2 black/grey. as for the steering wheel control interface, the only thing that is important is the output on pin 3 red/grey, when you hit a button on the wheel it makes a connection on this pin to ground through a certain size resistor, the radio see's the "value" of this resistor based on how much ground it see's and knows what button you pushed (the aftermarket unit converts this to a signal your new radio will understand). but we will get into that if we need to when we get onto that step. I would try to tap into that wire with the blue/white wire. If you would really like to double check then find the plug going into the amp and see what wires are there, if you have that black/grey wire there then it should be the right wire. if you have a meter test it for continuity. if this is a steering wheel control wire it will not go to the amp.

 

okay, did it. connected blue/white of head unit to black/grey of connector A. nothing changed. still very quiet.

i'm wondering if the blue/white actually has 12v power coming out.