We demonstrate the mutual coupling between a microcavity and a waveguide realized in a two-dimensional photonic crystal on an InP membrane. Coupling processes are evidenced by generating guided or cavity modes by photoluminescence and by measuring locally the diffraction losses. Depending on the transfer and loss dynamics, different coupling processes are found. Finite difference time-domain simulations and additional polarization resolved luminescence measurements are performed in order to further investigate the coupling procedure.