OnStar Schematics

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Vehicle Communication Interface Module Circuit Schematic (Except Y91)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Vehicle Communication Interface Module Circuit Schematic (Y91)

Courtesy of GENERAL MOTORS CORP.