The efficiency of using energy-intensive tractors in agriculture largely depends on the level of preparation for field work, which depends on the completeness of repair and maintenance activities. For assessmentin-place of the general technical condition of internal combustion engines, various diagnostic tools are used such as motor testers, crankcase gas flow meters, etc. The purpose of the study was to study the state of the issue and justify the need to develop a digital indicator for assessment-in-place of the general technical condition of the hydraulic drive control of the gearbox of energy-intensive tractors. The state of the issue of diagnosing and managing the reliability of agricultural machinery was analyzed in the work. It was found that it is necessary to control the time of the transient process in the hydraulic control system of the gearbox, as well as acceleration when changing gears. It was examined previously produced control and diagnostic equipment, and chose KI-12383 and “Effect-02.01” devices as a prototype for the development of the digital indicator. Modeling as well as design and testing of the prototype were carried out and the possibility of developing the digital indicator was proven, which can be used as a built-in diagnostic tool to justify the need for repair and maintenance of the gearbox. It was concluded that to monitor the general technical condition of the gearbox, a digital indicator was required, which will allow without making changes to the design (K-701, T-150K and their modern analogues) to obtain diagnostic data to justify repair and maintenance activities in order to reduce the risk of failures III complexity groups in the process of field work.