A Simulation-Based Approach to Analyze the Freedom From Interference for Automotive Functional Safety During Short-Circuit Events

Abstract

The complexity of automotive wiring harness systems increases constantly. Upcoming automated driving systems and X-by-Wire technologies increase the safety-related availability (SaRA) requirements of associated systems, as the driver cannot act as an immediate fallback. In particular, short-circuit events in lower-automotive safety integrity level or quality management load paths may cause an undervoltage in parallel safety-relevant paths, thereby potentially violating freedom from interference and SaRA requirements according to ISO 26262. This article proposes a simulation-based method to systematically analyze interference caused by short-circuit events in automotive wiring harness topologies. The method combines iterative fault injection into potential short-circuit paths, Monte-Carlo-based parameter screening, and a subsequent classification of influencing parameters. The effectiveness of the method is demonstrated using a simplified wiring-harness topology modeled in MATLAB/Simulink. The topology comprises a safety-relevant path containing a steering system, four potential short-circuit paths, and a base load representing the remaining consumers.The investigated parameters include ambient temperature, 12-V battery state of charge, short-circuit resistance, aging condition, and fuse tripping characteristics. A Monte Carlo study with 160 simulations was used to identify statistically significant parameter influences on fuse tripping time and minimum voltage. The results show that the proposed method can identify critical short-circuit paths, derive worst-case parameter combinations, and distinguish between relevant and nonrelevant interference scenarios. This method could complement conventional safety analysis and lead to improved design efficiency while supporting ISO 26262-compliant freedom-from-interference argumentation.