Sorry this gets kinda long but I want to be as clear as possible..PLEASE HELP!!!
The important parts are 1 and 3

1) Im in dire need of some assistance with wiring my new headunit!!! I have 2002 s60 t5 (w/ 85k) with the HU-803. It works fine, except for every now and then it randomly switches sources, other than that the only reason Im changing it is to have a usb and sub hookups (yes i know subs in a Volvo is frowned upon, but im 22 and that what we do) the radio going in is a Pioneer AVH-P1400DVD I had from my old ranger. I already have the headunit mounted in the dash kit from Tasca, and the antenna adapter. My only problem is with the harness for the radio. My car has 3 plugs total on the radio: antenna, power harness (green), and an odd black round one that says something about transmission on it (I think it has to do with the volume up as speed goes up function). I ordered the harness adapter, and got a 2 plug harness (gray and green), the green on fits but there's no place for the gray one. I searched for hours trying to find an answer, with nothing to show. I even went to crutchfeild, because everyone and there bother says they have it, and it tried selling me the one I already have THAT DOESNT WORK.

2) I started wiring up the green plug (since it works). I hooked up the power, constant, and ground. I plugged it in and it works fine, just cant hear anything obviously. I searched for a diagram and it said gray/red is front left and right positive, and gray was front left/right negitave, which made no sense because how would the stereo be able to send the signal to each speaker correctly, but Ive already learned how "sophisticated" this car is (aka overly complicated) so i didnt argue. I carefully removed the pins out of the gray plug (I smashed it with a hammer repeatedly, then took them out lol) for the left front +/- and plugged them into the corresponding places for the "front" speakers as listed in the diagram. AND IT WORKED, well the center dash speaker did only (I even tried playin with the blue signal wire and no change) Feeling lucky (but mainly being an idiot) I took a gamble and plugged the left rear +/- wires from the radio into the two that were remaining. That however DID NOT WORK, figures...The car made a couple click noises, the overhead lights dimmed out, another click, warning lights went on for SRS URGENT SERVICE, another click, dash dimmed out. I shut the car off and unpluged the radio and put it all back together with the stock radio. After a few restarts and lock/unlock of the door all was restored (except for the SRS light, which idc about, I can have it turned off in 20 min) I just really need some help figuring this out.

3) I already know these cars come with a amp, and believe that may be my issue. I also know the center speaker doesn't go off the amp, since I was apparently playing my music to loud and over loaded the amp leading all the speakers shutting off except the center one, my bad (after i resarted the car it was fine). Other then wiring in a new amp, is there a way to make my radio work with my car? Is a new amp even an option since the radio is actually a "module" for the car? PLEASE HELP!!

 

Does anyone know if this will work for me?

http://www.ebay.com/itm/Volvo-Stereo...-/200447134558

Im thinking I can plug the male plug i have (6-pin that i found out is for the amp) into the female side of this, plug the rca on this to my rca ports, and the remote to my hu remote? WILL THIS WORK?