Synopsis As Introduced Amends the Illinois Vehicle Code. Provides that counties are authorized to post signs that prohibit the driver of a commercial vehicle from operating or actuating any engine braking system that emits excessive noise. Prescribes the content of the sign. Provides that the Department of Transportation shall adopt rules providing for the erection and placement of these signs. Provides that the provision does not apply to the use of an engine braking system that has an adequate sound muffling system in proper working order that prevents excessive noise. Provides that it is a defense that the driver used the engine braking system in an emergency to avoid a collision with a person or another vehicle. Provides that a violation of the provision is an equipment violation punishable by a fine of $75.