01 Jimmy Bose WIring

I am looking for the Radio wiring color code for my 2001 GMC Jimmy. It has a factory 6 speaker Bose system installed.. I want to add an amplifier and sub box to the Factory stereo but cannot find the color codes anywhere! I need to find the line level out for the rear speakers and fear that they probably run through an amplifier that is located somewhere in the vehicle!.. Thanks in advance for the help. Chobes

I recommend using a line out converter, to tap into the rear speaker wires. This will step down the speaker level signal to line level, safe for your amp.My ex once told me I have a perfect face for radio.