<p>To standardize the reliability testing evaluation criteria for light-duty trucks powertrains, this study developed a set of procedures for conducting varying speed test across five conditions on the high-speed track of a proving ground. According to the test procedures, a reliability testing assessment was conducted on the light trucks drivelines. Focusing on the observed fracture failures of the driving shafts, semiaxles, and differential gears during the testing, a fatigue damage calculation model for the drivelines was established using Glyph Works, employing the rotating rainflow counting method to generate the rainflow cycle matrices for shafts and gears. Additionally, the metallographic structure, chemical composition, and heat treatment processes of the fractured component materials were detected and analyzed. The errors in machining precision induced the meshing area of the differential gears to shift outward, resulting in biased cyclic loading, the gears are directly subjected to alternating loads until failure. The metallographic structure and chemical element content of the driving shaft and semiaxle conformed to technical standards; however, the hardness of both the surface and core did not meet design specifications. The negative impact torque induced the local plastic deformation and cracks initiation in highest stress site, and with increasing number of loading cycles, the low-cycle fatigue fractures ultimately occurred.</p>