The processes are considered when the stages of weakening of the TED magnetic field are switched on on diesel locomotives of the TE10 type. The analysis of the unstable operation and automatic switching on of the transition relay at partial loads corresponding to the locomotive's speed at the rated load in operation is carried out. TED current algorithms are proposed for correcting the scheme for switching on the relay of transitions from a full field to a weakened field. A variant of the correction circuit is proposed to check its operation during operation. This principle has been violated since the creation of the TE10 diesel locomotive. It is still violated on TE10 diesel locomotives, except for diesel locomotives equipped with the USTA system.