Circuit/System Description
WARNING: This page is about a different car, the 2007 Suzuki XL7. However, it is still accessible from the selected car via links, so may be relevant.
Battery voltage for the center high mounted stop lamp (CHMSL) is applied from the CHMSL/DIMR 15 amp Fuse in the I/P electrical center to the body control module (BCM). When the brake pedal is applied, a signal is applied to the BCM. The BCM then applies a voltage to the CHMSL voltage supply circuit to the CHMSL.