This paper investigates the problem of designing a polytopic switched unknown input interval observer (SUIIO) for uncertain switched linear parameter varying (LPV) system characterized by unknown yet bounded uncertainties. First, we propose a SUIIO designed to estimate the lower and upper bounds of system states while remaining unaffected by unknown input disturbances. An algebraic unknown disturbance interval reconstruction is then established based on the relationship between the unknown input and the interval observer. Finally, a fault-tolerant controller is synthesized to guarantee the system's performance in the presence of faults. Sufficient Linear Matrix Inequalities (LMIs) conditions for stability and positiveness are formulated using Multiple Input-to-State-Stable (ISS) Lyapunov functions integrated with average dwell time (ADT). The efficacy of the proposed method is scrutinized through an evaluation of its performance in estimating and tracking vehicle lateral dynamics using Matlab-Simulink.