[f5fstop]

One way is to remove the left rear trim panel where the sub woofer would go and look for a connector, tied up to the harness that runs in that area.
I just looked up the wiring in the GM wiring diagrams, and hate to say they are incorrect, so I cannot say what type of connector, or what color wiring would be there.

(Guess I'll notifiy the right people on Monday about this problem in the wiring.)