N.J. Stat. Ann. § 39:3-64.2

Every itinerant vendor's vehicle shall be equipped with a signaling system that in addition to signaling turning movements as provided for in section 39:4-126 of the Revised Statutes shall have a switching arrangement that will cause the 2 front turn signals and the 2 rear turn signals on the vehicle to flash simultaneously as a vehicular traffic hazard warning signal. The system shall be capable of flashing simultaneously with the engine operating or stopped.