Achieving freedom from interference as required by ISO 26262 in modern vehicles represents an increasing challenge from the perspective of functional safety. The electric power steering (EPS) faces particularly strict requirements due to higher axle loads, higher levels of ADAS (L3+), and steer-by-wire systems. This results in higher ASIL classifications and reduced fault-tolerant time intervals (FTTI). In the event of a short circuit in the 12V wiring harness, conventional automotive fuse trip times may exceed the allowed FTTI. If the resulting undervoltage drops below a critical threshold, the overarching safety goal of the steering system is violated.

We present a new approach developed within a research project that ensures freedom from interference specifically for safety-relevant components, like the EPS. A capacitor-based backup system serves as cold redundancy, supplying power to the EPS until the fault in the 12V wiring harness is resolved. This approach requires only minimal modifications to the existing E/E architecture, making it cost-effective for implementation in already existing platforms and therefore enabling L3+ ADAS functions to be implemented in the current generations of vehicles.