I'm french too, thanks to everyone, i've done this and its working.
I use luks encryption for home and root files. If it can help some guys
vim /etc/vconsole.conf Add this
KEYMAP=fr-latin9 and also check this
vim /etc/mkinitcpio.conf It MUST be in the good order
HOOKS=(base udev autodetect keyboard keymap consolefont modconf block encrypt lvm2 filesystems fsck) Regenerate initrd
mkinitcpio -P