July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Serial Data Gateway Module (HP2)

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Serial Data Gateway Module (HP2) Wiring Schematic

Courtesy of GENERAL MOTORS CORP.