In a 1999 Buick Century's door speaker wiring, the green wire is almost certainly the
negative (-) speaker wire. However, it's
crucial to confirm this with a multimeter before connecting anything. Car wiring colors aren't standardized across all manufacturers and models, even within the same year.
Do not rely solely on this information. Use a multimeter to test the wires for continuity to ground (the car chassis) and to the positive (+) wire (which may be other colors such as gray, blue, or even purple). Improper wiring can damage your speakers or your car's electrical system.
