Trans Tech Bus (Trans Tech) is recalling certain 2020 Roadstar, ST Aero and SST buses built on 2019 Chevrolet Express cutaway chassis. The specific models are AC139SSSA409,AC139SSSP500, CC139DMSA409, CC139DMSA500, CC139DMSP500, CC159DMSA509, CC159DMSA600,EC139DBSP400, SC139DSFP500, SC139DSSA409, SC139DSSA500, SC139DSSP500, SC159DSFP600, SC159DSSA509, SC159DSSA600, SC159DSSA603, SC159DSSP600, and SC177DSSA603. The seatbelt-unfastened warning light will not illuminate for approximately five seconds after the ignition is moved to the “on” or “start” position. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 208, “Occupant Crash Protection.”