Circuit/System Description
WARNING: This page is about a different car, the 2007 Chevrolet Monte Carlo and 2007 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) applies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimming switch, which is part of the headlamp switch. When the dimming switch is placed in the desired position, the dimmed voltage setting is applied from the interior lamp dimming switch through the I/P dimming return circuit to the BCM. The BCM then applies the dimmed voltage to the I/P lamps supply voltage circuit. The I/P lamps in the headlamp switch, I/P cluster, door lock switch, power window switch, and power mirror switches then dim to the correct level.