<p>This study proposes and evaluates a vehicle integration control unit (VICU) that enables cooperative control among braking, steering, and propulsion systems to enhance fail-operational capability of the vehicle chassis domains. The VICU adopts a centralized architecture that reallocates control authority across functional domains in the event of a fault, thereby improving vehicle stability and safety under degraded conditions. Although various fault-tolerant control strategies have been introduced in prior research, real-vehicle implementation of cross-domain cooperative control remains limited. To address this, a VICU-based integrated control platform was developed and applied to a vehicle under test (VUT). After verification in SILS and HILS environments, the platform was subjected to eight distinct fault scenarios, including braking actuator faults, steering sensor failures, and propulsion imbalance cases, to quantitatively assess dynamic stability responses. The results demonstrate that the VICU effectively maintained key performance indicators—such as yaw rate, lateral acceleration, and steering sensitivity—through cooperative control across domains under fault conditions. These findings validate the practical applicability of the proposed architecture for realizing fail-operational functionality in VUT-based testing, highlighting its ability to perform real-time control handover and cross-domain compensation across braking, steering, and propulsion systems.</p>