Where is the onstar module located on a 2004 Tahoe?

In a 2004 Chevrolet Tahoe, the OnStar module is typically located in the rear compartment, specifically behind the trim panel on the driver's side. To access it, you may need to remove the side trim and possibly a few screws. The module itself is usually mounted to the vehicle's structure and connected to the wiring harness. Be sure to disconnect the battery before working on it for safety.