Hands-free access system for a motor vehicle including an electronic communication module able to transmit a low-frequency interrogation signal to a badge or portable identification device, a central control unit able to control the communication module and an electronic connection bundle with two wires (4, 5) electrically connecting said central control unit to said electronic communication module, said electronic communication module including a resonant circuit matched to a tuning frequency and comprising a transmission coil in series with a tuning capacitor, said resonant circuit (20, 21) being able to transmit a low-frequency interrogation signal at said tuning frequency to a badge or portable identification device, and a manually actuated triggering member, the actuation of which is used to trigger the transmission of said interrogation signal, said system being characterized in that the triggering member is a switch button connected in series with at least one resistor to form an electric dipole, and in that said electric dipole is electrically connected in parallel across all or part of the resonant circuit (20, 21), said system being furthermore characterized in that the central control unit is configured to control the electronic communication module via the electric connection bundle with two wires (4, 5), said central unit including: - a low-frequency voltage generator able to be electrically connected to the terminals of the resonant circuit of the electronic communication module via the two wires (4, 5) of the connection bundle for the transmission of said interrogation signal; - a connection to a DC electric voltage source (+V CC) able to connect the electronic module to said source via a first wire of the two wires of the connection bundle; - a detection circuit (31, 32; 31', 32) able to deliver an output signal indicative of the open or closed state of the switch button; and - a microcontroller configured to receive the output signal of the detection circuit (31, 32; 31', 32) and to control, when the detection circuit (31, 32; 31', 32) detects a closed state of the switch button, the generation by said low-frequency voltage generator of a low-frequency supply signal of the resonant circuit for the transmission of the interrogation signal, the detection circuit (31, 32) including a means for measuring the current flowing between said first wire and the connection to the DC voltage source (+V CC), configured to deliver an output voltage (V I) indicative of said current, and a two-input voltage comparator configured to compare said output voltage with a reference voltage and to deliver said output signal depending on the comparison. - a low-frequency voltage generator able to be electrically connected to the terminals of the resonant circuit of the electronic communication module via the two wires (4, 5) of the connection bundle for the transmission of said interrogation signal; - a connection to a DC electric voltage source (+V CC) able to connect the electronic module to said source via a first wire of the two wires of the connection bundle; - a detection circuit (31, 32; 31', 32) able to deliver an output signal indicative of the open or closed state of the switch button; and - a microcontroller configured to receive the output signal of the detection circuit (31, 32; 31', 32) and to control, when the detection circuit (31, 32; 31', 32) detects a closed state of the switch button, the generation by said low-frequency voltage generator of a low-frequency supply signal of the resonant circuit for the transmission of the interrogation signal, the detection circuit (31, 32) including a means for measuring the current flowing between said first wire and the connection to the DC voltage source (+V CC), configured to deliver an output voltage (V I) indicative of said current, and a two-input voltage comparator configured to compare said output voltage with a reference voltage and to deliver said output signal depending on the comparison.