As automotive electronic systems aiming for a safe and secure automobile society continue to develop, the control specifications of the ECU are becoming increasingly complex. When attempting to validate control specifications that cooperatively control different control specifications, control specification developers must consider various validation viewpoints. They narrow down the validation viewpoints based on rules from past experience, describe timing charts, and validate the specifications. However, due to complicated specifications, empirical rules do not pass, and specification mismatches are often found after actual systems completion. On the other hand, a block diagram simulator is a tool to verify control specifications. Since these tools are aimed at modeling and verifying the system design, it is efficient to describe how to implement the system. However, first it is necessary to verify the consistency between the model and the specifications. It is inefficient to verify the specification itself. In order to respond to complicated control specifications, we are working to build the simulation environment necessary to efficiently validate specifications in the specification design phase. In this paper, we describe a method to validate communication mismatches caused by different reception enable/disable timing specified in specifications when ECUs with different control specifications communicate with each other. By modeling using a constraint real-time specification language, we show that we can simulate the timing chart quickly and can quickly validate the specifications even if different control specifications are mixed together. In addition, we show that it is possible to validate the specification in the specification design phase by creating simulation models with state transition diagrams and block diagrams that have the same abstraction level as the specifications.