Circuit/System Description
WARNING: This page is about a different car, the 2008 GMC Sierra and 2008 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The 4 high indicator circuit consists of an indicator lamp feed circuit and an 4 high indicator lamp control circuit. When the 4 high mode has been selected, current is supplied to the 4 high indicator lamp by the interior lights dimming circuit, traveling through the 4 high indicator lamp LED, at which time the transfer case shift control module supplies the ground through the 4 high indicator lamp control circuit.