Abstract: A vehicle (V) is fitted with a primary receiver/emitter cell (1) containing a first code (C1) and a secondary receiver/emitter cell (2) containing a second code (C2) as well as a first representation (FR1) of the first code (C1). The two cells receive respectively primary (EIB1, EIA1) and secondary (EIB2) selective interrogations (OI) to which they respond by emitting respectively a primary response (ERB 1, ERA 1) representing the first code (C1) and a secondary response (ERB2) representing the second code (C2). Then the secondary cell (2) responds alone to a complementary interrogation (EIC) which contains a second representation (SR2) of the first and second codes emitted, together with an order.