My rear speakers have not worked since i bought my car, the rear speakers are standard and in bad shape. I bypassed my stock amp using this method http://www.skylinesaustralia.com/forums/topic/203299-r32-factory-amp-bypass-diy/
After bypassing the amp the rear speakers still did not have any power, I then pulled out the head unit to reveal a real birds nest of twist and tape wiring with only the front speakers being wired in.
I printed off a wiring diagram to work out whats going on - http://www.installdr.com/Harnesses/Nissan-Wiring.pdf
So now i find that the nissan wire colours are all wrong and some doubled up according to 2 different wiring diagrams.
I have checked the wires going into all the speakers and noted down the colours, barely any of these colours match up with to the wires behind the stereo.
If anybody thinks they would be able to help sort this out please PM me.