Diagnosis allows to assess the condition of the diesel engine without disassembly of the vehicle. The book deals with the theoretical background to the justification of the assessment of indicator parameters and imbalance of diesel diagnostic parameters obtained by vibro - acoustic method. Presented primary converters and a processing of diagnostic signal electric. Developed technique and the manufactured equipment and the measuring means for receiving and processing of the vibro-signal on the diagnosis of a diesel engine. The results of the proposed research is flowchart the scan tool. Developed technology evaluation of the maximum gas pressure in the cylinder of a diesel engine by using a manufactured device IMP-LAI (Indicator measurement parameters - Leningrad agricultural Institute) and unbalance of a diesel engine with use of the developed electronic diagnostic device and AMT-K-539. The result was a technical requirement for the diagnostic tool for the evaluation of indicator parameters and unbalance of diesel. For scientific workers and specialists for technical diagnostics of diesel engines.