Electromagnetic switch for the starter of a heat engine comprising: - a first terminal, - a second terminal, - a first mobile contact which is situated between the first and second terminals (B1, B2), and which is mobile between a rest position and a power supply position, - an adjustable core, of a first coil, intended to actuate a system for operating a drive assembly of the starter, controlling the displacement of the first mobile contact, characterized by - a second mobile contact which is situated between the first mobile contact and the second terminal and which is mobile, between a disconnected position and a connected position, by a core of a second coil and a spring, the switch being able to be placed, depending on the power supply of the coils, in three operating states: - a rest state in which the first mobile contact is electrically isolated from the two terminals (B1, B2) and in that the two terminals are isolated from one another, - a state of engagement in which: - the first mobile contact is in a position of engagement between the power supply position and the rest position and is in electrical contact with the first electrical terminal, - the second mobile contact is in the rest position and in electrical and mechanical contact with the first mobile contact, - the second terminal is electrically isolated from the mobile contacts and from the first terminal, - a power supply state in which: - the first mobile contact is in the power supply position and is in electrical contact with the second terminal through the second mobile contact and is in electrical contact with the first terminal, and - the second mobile contact is in the connected position and is in electrical and mechanical contact with the second terminal. - a first terminal, - a second terminal, - a first mobile contact which is situated between the first and second terminals (B1, B2), and which is mobile between a rest position and a power supply position, - an adjustable core, of a first coil, intended to actuate a system for operating a drive assembly of the starter, controlling the displacement of the first mobile contact, characterized by - a second mobile contact which is situated between the first mobile contact and the second terminal and which is mobile, between a disconnected position and a connected position, by a core of a second coil and a spring, - a rest state in which the first mobile contact is electrically isolated from the two terminals (B1, B2) and in that the two terminals are isolated from one another, - a state of engagement in which: - the first mobile contact is in a position of engagement between the power supply position and the rest position and is in electrical contact with the first electrical terminal, - the second mobile contact is in the rest position and in electrical and mechanical contact with the first mobile contact, - the second terminal is electrically isolated from the mobile contacts and from the first terminal, - the first mobile contact is in a position of engagement between the power supply position and the rest position and is in electrical contact with the first electrical terminal, - the second mobile contact is in the rest position and in electrical and mechanical contact with the first mobile contact, - the second terminal is electrically isolated from the mobile contacts and from the first terminal, - a power supply state in which: - the first mobile contact is in the power supply position and is in electrical contact with the second terminal through the second mobile contact and is in electrical contact with the first terminal, and - the second mobile contact is in the connected position and is in electrical and mechanical contact with the second terminal. - the first mobile contact is in the power supply position and is in electrical contact with the second terminal through the second mobile contact and is in electrical contact with the first terminal, and - the second mobile contact is in the connected position and is in electrical and mechanical contact with the second terminal.