65 ILCS 5/6-4-10
At the first meeting of the council after this Article 6 becomes effective in any city or village, it shall pass a general ordinance (1) amplifying the powers and duties of the mayor in conformity with this Article 6, (2) defining the scope of each department and of each division thereunder, (3) defining and prescribing the qualifications, powers and duties of appointive officers and employees, (4) fixing the salaries of all appointive officers and employees, (5) providing for independent audits of all accounts of the city or village, which audits shall be conducted independently of the mayor by some person selected by the council, (6) repealing all city ordinances in conflict with the provisions of this statute. Full reports of such audits shall be filed in the public records of the city or village. The power with respect to such audits shall not be construed to limit the responsibility of the mayor for the proper expenditure of city or village funds.
65 ILCS 5/6-4-10