HKS F-Con V Pro Harness For Toyota Mark II JZX100 (4202-RT026)F CON iS can control the latest advanced engines. Just connect to a stock ECU with a vehicle specified harness without modification. HKS "F CON iS" is a piggy back ECU for fuel and ignition management as well as new features. Functions for fuel and ignition controls are inherited from the previous model F CON SZ. In addition to it, function to collect OBD II diagnosis data was added for correction of setting due to stock close loop correction values