Behavioral synthesis automatically compiles an electronic system-level description of a hardware design into an RTL implementation. Scheduling in behavioral synthesis is an important, sophisticated, and error-prone transformation which converts the untimed or partially timed description into a fully timed implementation. We present a scalable equivalence checking algorithm for validating scheduling transformations. Our approach accounts for control/data dependency, scheduling modes, and subtle interface protocols. We successfully validated designs with tens of thousands of lines of RTL synthesized by commercial synthesis tool, demonstrating the viability of our approach.