Circuit/System Description
WARNING: This page is about a different car, the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The 2 high indicator circuit consists of an interior lights dimming circuit and an 2 high indicator control circuit. When the 2 high mode has been selected, current is supplied to the 2 high indicator by the interior lights dimming circuit, traveling through the 2 high indicator LED, at which time the transfer case shift control module supplies the ground through the 2 high indicator lamp control circuit.