The automotive electronic control unit outputs control signals using electrical signals of various input sensors installed in the vehicle to control the state of the engine, automatic transmission, and electric power steering (EPS). These units are installed inside the vehicle or engine room, and the temperature rises and falls by several tens of degrees due to the heat of the engine and the self-heating of the electronic control unit. Therefore, it was exposed to a thermal fatigue environment due to the difference in the coefficient of thermal expansion between the components, which caused frequent component damage. Solder cracks due to thermal fatigue in electronic control units are a key failure mode. However, because of its great heat capacity, the electronic control unit for automobiles took a long time to attain the desired temperature of high or low, and as a result, the 1,000-cycle test for thermal fatigue life verification required 3,167 hours (or 4.4 months). Therefore, in this study, the thermal shock cycle test time for the verification of the thermal fatigue life of electronic control units for automobiles was reduced by dividing it into two types.