The training is intended for maintenance workers, service workers, electricians and maintenance workers of injection machines working with electrical systems. Alarm messages and the history of the operator panel alarms are discussed in detail. Individual cards provided by the manufacturer of electrical diagrams are explained, along with their nomenclature. Electrical diagnostic functions are analyzed. The acquired knowledge is used in the further part of the training to analyze the electrical diagrams of the machine, made available during the classes. Then, training participants carry out a series of electrical diagnoses at the production stand with the use of service tools.