Strong oscillations in density, temperature and floating potential, coherent with magnetic perturbations, are observed with edge probes and limiters in the TOSCA Tokamak for discharges with large amplitude Mirnov activity. This edge mode is identified as having an (m, n)=(3,1) symmetry (q(a)<4.5) which exists simultaneously with an internal (2,1) magnetic island. The edge mode is probably the toroidal side band of the principal m=2 tearing mode as predicted by toroidal resistive instability calculations. Various probe techniques were used to investigate the radial structure, density, potential and temperature oscillations associated with the phenomenon thus giving detailed information on the mode properties and its interaction with the limiters. The role of the mode/limiter interaction in disruptions is discussed.