<![CDATA[Purpose - This study aims to investigate the probable root cause of Integrated Charging Control Unit (ICCU) failure in an electric vehicle through the integration of service-level diagnostic information, electrical measurements, and physical failure evidence. Research Design - A descriptive-analytical single-case study was conducted on one failed ICCU unit obtained from a Hyundai Ioniq electric vehicle. The investigation included the evaluation of Diagnostic Trouble Codes (DTCs), freeze-frame parameters, insulation resistance measurements, fuse continuity testing, and physical inspection of damaged components. Findings - Diagnostic analysis identified an active DTC, P1A9096 (DC/DC Converter Input Voltage Sensor Fault), together with several historical low-voltage and communication-related DTCs. Freeze-frame data showed that the OBC internal DC-link voltage, charging voltages, and charging currents were recorded at 0.0 V and 0.0 A, indicating that the charging conversion process was unable to establish normal energy transfer. Physical inspection revealed localized burn marks, degraded thermal interface materials, printed circuit board contamination, and residue accumulation around critical electrical components. Electrical testing further identified an insulation resistance of 1.47 MΩ and an open-circuit condition of the high-voltage fuse. The integrated evidence indicates that the failure most likely originated within the ICCU power conversion stage, whereas the observed thermal degradation, insulation deterioration, and environmental contamination are interpreted as contributory factors or evidence-supported hypotheses rather than conclusively verified initiating mechanisms. The open-circuit high-voltage fuse is interpreted as the final protective response to the abnormal electrical event. Implications - The findings are derived from a single failed ICCU unit and therefore should be interpreted as an evidence-based case study rather than confirmation of recurring failure patterns or generalized ICCU reliability characteristics. Several proposed failure mechanisms remain evidence-supported hypotheses because advanced measurements, including thermal imaging, semiconductor parameter testing, capacitance measurements, coolant characterization, and microscopic material analysis, were not performed. Originality - This study demonstrates the value of integrating diagnostic information, electrical measurements, and physical evidence to support evidence-based investigation of ICCU failures. The proposed case-based diagnostic approach provides practical insights for understanding failure mechanisms in electric vehicle charging systems and establishes a foundation for future multi-case investigations.]]>
