Michigan Compiled Laws, Chapter 257. Motor Vehicles § 257.648

Sec. 648. (1) The operator of a vehicle or bicycle upon a highway, before stopping or turning from a direct line, shall first determine that the stopping or turning can be made in safety and shall give a signal as required in this section.

(2) Except as otherwise provided in subsection (5), a signal required under this section shall be given either by means of the hand and arm in the manner specified in this section, or by a mechanical or electrical signal device that conveys an intelligible signal or warning to other highway traffic.

(3) When a person is operating a vehicle and signal is given by means of the hand and arm, the operator shall signal as follows:

(4) When a person is operating a bicycle and signal is given by means of the hand and arm, the operator shall signal as follows:

(5) A commercial motor vehicle, other than a commercial motor vehicle in transit from a manufacturer to a dealer, in use on a highway shall be equipped with, and required signal shall be given by, a signal lamp or mechanical signal device when the distance from the center of the top of the steering post to the left outside limit of the body, cab, or load of the commercial motor vehicle exceeds 24 inches, or when the distance from the center of the top of the steering post to the rear limit of the body or load of the commercial vehicle exceeds 14 feet. The measurement from steering post to rear limit applies to a single vehicle or combination of vehicles.

(6) A person who violates this section is responsible for a civil infraction.