Stereo Wiring

[BBBurban at aol.com]

Hi all. Was attempting to install my Alpine in place of the stock 1990 90q20v 
stereo and had almost everything done when I ran out of light.  I am down to 
the last plug (the top one that contains the rear speaker feeds) but can't 
seem to figure out the wires.  The two positive speaker inputs and the 
negative are easy.  This leaves me with four wires that I have no idea what 
they are.  If anyone can shed some light on these for me it would make my 
day.  Thanks all 

Hank 90q20v (driving without tunes)