I just spoke to a police officer. There are no blanket curfew for minors. New drivers have restrictions, but there are no rules outside the car. The only curfews are imposed on individuals by court order.
Although anyone 17 or older doesn't have a curfew, under 17 is 10:30 pm- 6:00am Monday-Thursday, and 11:30pm-6:00am Friday & Saturday. Here is the link to Cook County Curfew...