65 ILCS 5/5-3-10
At the first meeting of the council or village board after this Article 5 becomes effective in any city or village, it shall pass a general ordinance (1) amplifying the powers and duties of the manager in conformity with this Article 5, (2) defining the scope of each department and of each division thereunder, (3) defining and prescribing the 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 manager by some person selected by the council or the village board. 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 manager for the proper expenditure of city or village funds. The council or board may by such ordinance (1) assign appointive officers and employees to one or more of the departments, (2) require an appointive officer or employee to perform duties in 2 or more departments, (3) make such rules and regulations as may be necessary or proper for the efficient and economical conduct of the business of the city or village.
65 ILCS 5/5-3-10