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Circuit/System Description

WARNING: This page is about a different car, the 2010 Cadillac SRX. However, it is still accessible from the selected car via links, so may be relevant.

The body control module (BCM) supplies a voltage reference through the backlight dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the backlight dimmer switch to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage through the backlight lamp control circuit. This will illuminate the ignition mode switch halo lamp.

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