Abstract: An automotive external lighting system uses pulse width modulation to drive a single filament for turn signaling and park signaling purposes. A control circuit generates a variable brightness signal based on a predetermined brightness level, and an external lamp produces external illumination based on the brightness signal. A single wire is therefore able to electrically connect the control circuit to the external lamp. The control circuit includes a microcontroller for generating a pulse width modulated signal, and a high side driver for driving the lamp in response to the pulse width modulated signal. When the pulse width modulated signal has a duty cycle corresponding to a parking brightness level, the filament will produce less illumination than in the case of turn signaling.