Tapping Signal from Data Cable-Help?

[Four Point Six]

I have some woofers and an amp from my last truck that I'd like to put in my car. I found an article about using a line converter to tap RCA signal using the data cable. Once I found the cable, it was obvious that the previous guy had spliced into it before, and even has the connector labeled(L/R +/-). There are are four wires-two black/green and two white/black. My question is this: Once the two green/black wires leave the plug, they are spliced together. These two wires should be the right and left positive, no? I cut the insulation farther back into the group of wires that the plug leads to and can't find the rest of the missing wire. Whats going on here? Are the positives two supposed to be wired together? Also, the line converter I got has 8 "channels" with RCA outs (left/right pos/neg front/rear). I should be able to just use four channels and disregard the front/rear thing right? Any advice on getting this wired up and working would be great.
Thanks

 

[Four Point Six]

Anyone?

 

[Red2000GT]

We need more detailed information. Where exactly did you find the "data cable" ? It sounds like you've got the wrong ones or you have the pre-amp signal wires(which should not be used to run into the adaptor). Yes you can ignore the front rear thing on the converter and just use one pair.