76 pontiac bonneville car stereo wiring

I am looking for a car stereo wiring diagram for a 1976 Pontiac Binneville Brougham. Thanks.

What color are the wires behind the radio?

yellow...accessory power, grey...illumination, black...ground, speakers could be tan/grey...left front +/-, light GREEN/ dark green...right front +/-, OR light GREEN/ black...spkr +/-, same for both sides. BROWN / yellow...left rear +/-, dark blue/light blue...right rear +/-, OR brown...left rear +, dark blue...right rear +, speaker - common to vehicle chassis.

Or use a test light and a PP3 battery.

Thanks for all the help! I really appreciate it.Bj hammon

Not sure. Just wanted to do all my research, before I install my after market stereo.Bj hammon

If it is a common ground system, you have to run wires to each speaker.

I also thought that Craig but was too lazy to mention it! Surely they'd got rid of that system by then? I remember early VW Siroccos had a common ground on the rear speakers.

I do not remember when they went away from common ground on the GM products. I know it was mid 80s when they started making high power radios. I do not remember having to rewire as many GMs as I did Ford products. Or using those old floating ground adapters. Those things defeated the purpose of high power. They simply used the positive speaker wires with a large capacitor to block the 6 volts DC on the speaker wires of the new decks.

Change over from the GM common ground system was late 70's, right before I started doing car audio. Yes, I'm old.