A method and device for triggering, via an RFID reader (5) endowed with a transmitting antenna (6), a procedure for actuating an element for locking/unlocking the access doors (2) of a motor vehicle (1). A coil (7) is arranged in the vicinity and in the field of action of the transmitting antenna (6), and: the RFID reader (5) is commanded so as to control the successive transmission of electromagnetic pulses of the same power, upon each pulse, a value representative of the electrical voltage at the terminals of the coil (7) is measured, and the procedure for actuating the locking/unlocking element is triggered in the event of a variation in the measured values greater than a determined value.