Functional Safety and Cybersecurity in Zonal ECU Architectures: A Unified Design Approach

The shift to zonal electronic control units (ECUs) is transforming vehicle electrical architectures, consolidating multiple functions into fewer, more powerful computing nodes. While this reduces wiring and improves scalability, it also concentrates both safety and security risks. This paper presents a unified design approach that integrates ISO 26262 functional safety with ISO/SAE 21434 cybersecurity to ensure that zonal ECUs remain both fail-operational and resilient against attacks. The proposed architecture combines dual-core lockstep processing for ASIL-D fault detection with secure boot, hardware security modules (HSMs), and in-vehicle intrusion detection. A prototype implementation on an NXP S32G platform demonstrates fault coverage exceeding 99% while preventing common cyber exploits, without compromising real-time system performance. Case studies highlight how unified safety-security co-engineering improves reliability, reduces residual risk, and simplifies compliance processes. This work provides OEMs and Tier-1 suppliers with a practical roadmap for designing safe and secure zonal ECUs, enabling next-generation vehicles to meet stringent safety and cybersecurity standards while supporting the increasing demands of ADAS and electrification.