(625 ILCS 5/11-804) (from Ch. 95 1/2, par. 11-804)
    Sec. 11-804. When signal required.
    (a) No person may turn a vehicle at an intersection unless the vehicle is in proper position upon the roadway as required in Section 11-801 or turn a vehicle to enter a private road or driveway, or otherwise turn a vehicle from a direct course or move right or left upon a roadway unless and until such movement can be made with reasonable safety. No person may so turn any vehicle without giving an appropriate signal in the manner hereinafter provided.
    (b) A signal of intention to turn right or left when required must be given continuously during not less than the last 100 feet traveled by the vehicle before turning within a business or residence district, and such signal must be given continuously during not less than the last 200 feet traveled by the vehicle before turning outside a business or residence district.
    (c) No person may stop or suddenly decrease the speed of a vehicle without first giving an appropriate signal in the manner provided in this Chapter to the driver of any vehicle immediately to the rear when there is opportunity to give such a signal.
    (d) The electric turn signal device required in Section 12-208 of this Act must be used to indicate an intention to turn, change lanes or start from a parallel parked position but must not be flashed on one side only on a parked or disabled vehicle or flashed as a courtesy or "do pass" signal to operators of other vehicles approaching from the rear. However, such signal devices may be flashed simultaneously on both sides of a motor vehicle to indicate the presence of a vehicular traffic hazard requiring unusual care in approaching, overtaking and passing.
(Source: P.A. 78-1297.)