The research presented developed a hardware-in-the-loop system for testing in-truck safety technology. The paper describes the hardware and software components that were required to develop the system, how the various components were integrated, and some initial validation tests of the system. Specifically, the paper describes how the hardware-in-the-loop system interacted with the TruckSim simulator to produce realistic results. The models used for the validation of the system are detailed; a demonstration of the system validity follows. The absolute and relative errors between the TruckSim simulation results and the hardware-in-the-loop simulation were demonstrated by a comparison of the temporal variation in velocity and the truck roll angle. The study demonstrated the benefits of an accurate hardware-in-the-loop system for testing future in-vehicle safety systems.