On the basis of a classical model of triboelectrochemistry, a new approach is proposed based on an impedance ratio of a mechanical perturbation and an electrochemical response. Theoretical derivation, experimental setup and application to a passive stainless steel in a borate solution are presented. Transient characteristics yielded by the technique, associated to a permanent tribological regime, are found to obey a two-time-constant law. They are discussed and compared to the global repassivation transients of the material after switching off the abrasive friction.