Hi Pin, thank for your answer, and yes, there are 5 volts between pins 1 & 2.
When I checked all connections, I realised that I hadn't wired JP1.2 to ECU reference voltage. Should I ? On message #8 on the scheme I made, we can see I traced this connection with dots because I wasn't sure if it was necessary since the ECU is not motronic but its ref voltage is 5V. What do you think ?
Anyway, I made a photo of the back of the converter, you can find it there :
https://www.dropbox.com/s/cb89zhyl8e...0side.jpg?dl=0