In a 2003 Harley-Davidson Sportster, the ignition module is typically located under the seat, near the rear fender. To access it, you would need to remove the seat by unlocking and lifting it. Once the seat is removed, you may be able to locate the ignition module mounted on a bracket or frame under the seat area.
Please note that the exact location and configuration of components can vary depending on the specific model and any modifications that may have been made. It's always recommended to consult the motorcycle's owner's manual or a qualified technician for precise information regarding the location of specific components on your particular Sportster model.