Circuit/System Description
WARNING: This page is about a different car, the 2017 Chevrolet Spark. However, it is still accessible from the selected car via links, so may be relevant.
The rear fog lamp switch signal circuit is grounded through a resistor momentarily when the rear fog lamp switch is pressed. The body control module (BCM) responds to the rear fog lamp switch input by applying battery voltage to the rear fog lamp control circuit which illuminates the rear fog lamp.