Circuit/System Description
WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The 4 low indicator circuit consists of an interior lights dimming circuit and an 4 low indicator lamp control circuit. When the 4 low mode has been selected, current is supplied to the 4 low indicator lamp by the interior lights dimming circuit, traveling through the 4 low indicator lamp LED, at which time the transfer case shift control module supplies the ground through the 4 low indicator lamp control circuit.