I have found a solution.
I was right. LS-372 needs a +5V signal to power up and the uSDC20 use a "short to ground" signal.
So I modified the uSDC20 adding a little home-made circuit with 78L05 5V regulator a PNP transistor. I also modified routage and added a 4-PINS MOLEX connector in order to connect the USDC directly through the motherboard.
Male MOLEX connector :
Fixations and female MOLEX connector on motherboard :
I will have more free time this week end and I will make updates on my thread.
I hope finish this project before the end of the year (All hardware but not the paint).