Pulse dynamics arising in a three-component reaction–diffusion system with FitzHugh–Nagumo-type nonlinearity are investigated. Numerical investigations reveal that the pulse exhibits three distinct types of behavior as a control parameter is varied. To analytically examine these behaviors, finite-dimensional ordinary differential equations (ODEs) are derived to describe the individual motions of the pulse interfaces. The reduced ODE system successfully reproduces the pulse dynamics observed in the original reaction–diffusion system and clarifies the global bifurcation structure underlying the dynamics. The reduction method is further extended to multiple-interface solutions, offering insight into the mechanisms responsible for the numerically observed transient behaviors.
