Willpatel_Kendmirez:
What makes you think it doesn't "seem" to work? Have you printed the digitalReads to make sure they have the values you think they have, and then that of Mode1 too?
Seems that pin S1...S4 have switches or buttons on: how are they wired and pinMode()-ed?
I chekt it with a while loop and it didn't have any effects.
Here is the whole programme, but it´s not finish yet. So don't be scared if its not "beutifull" 
// ENTREE matériel
#define S5 41 // ON
#define S6 112 // OFF
#define S1 2 // BP position 1
#define S2 3 // BP position 2
#define S3 55// BP position 3
#define S4 56// BP position 4
#define B1 4 // Capteur 1
#define B2 5 // Capteur 2
#define B3 6// Capteur 3
#define B4 7 // Capteur 4
#define SAV 76// BP Marche avant
#define SAR 77// BP Marche arriere
#define H1 8
#define H2 9
#define H3 90
#define H4 99
// SORTIE matériel
#define SORTIE_Lampe1 10
#define SORTIE_Lampe2 11
#define SORTIE_Lampe3 15
#define SORTIE_Lampe4 16
#define SORTIE_Lampe5 17
#define SORTIE_Relais1 18
#define SORTIE_Relais_AV 12
#define SORTIE_Relais_AR 13
/*
void mise_sous_tension(){
if((digitalRead(S5)==1)&&digitalRead(S6)==1){
digitalWrite(SORTIE_Relais1, 1);
}
if(digitalRead(S6)==0){
digitalWrite(SORTIE_Relais1, 0);
}
}
*/
void setup() {
// Les Entrées
pinMode(S5, INPUT);
pinMode(S6, INPUT);
pinMode(S1, INPUT);
pinMode(S2, INPUT);
pinMode(S3, INPUT);
pinMode(S4, INPUT);
pinMode(B1, INPUT);
pinMode(B2, INPUT);
pinMode(B3, INPUT);
pinMode(B4, INPUT);
pinMode(SAV, INPUT);
pinMode(SAR, INPUT);
pinMode(H1, INPUT);
pinMode(H2, INPUT);
pinMode(H3, INPUT);
pinMode(H4, INPUT);
// Les Sorties
pinMode(SORTIE_Lampe1, OUTPUT);
pinMode(SORTIE_Lampe2, OUTPUT);
pinMode(SORTIE_Lampe3, OUTPUT);
pinMode(SORTIE_Lampe4, OUTPUT);
pinMode(SORTIE_Lampe5, OUTPUT);
pinMode(SORTIE_Relais1, OUTPUT);
pinMode(SORTIE_Relais_AV, OUTPUT);
pinMode(SORTIE_Relais_AR, OUTPUT);
}
void loop(){
/*
//+++++++++++++++++++++++++++++++++++++++++++++++++Création des variables "mode" :
int Mode1,Mode2,Mode3,Mode4;
if(digitalRead(S1)==1){
Mode1=1;
}
//+++++++++++++++++++++++++++++++++++++++++++++++++Envoyer la pièce vers la position 1
if(digitalRead(S1)==1&&(digitalRead(B4)==1||digitalRead(B2)==1||digitalRead(B3)==1)&&digitalRead(S2)==0&&digitalRead(S3)==0&&digitalRead(S4)==0){
digitalWrite(SORTIE_Relais_AR, 1);
digitalWrite(SORTIE_Lampe1, 1);
}
while(Mode1==1 && digitalRead(B1)==0)
{
digitalWrite(SORTIE_Relais_AR, 1);
digitalWrite(SORTIE_Lampe1, 1);
}
//+++++++++++++++++++++++++++++++++++++++++++++++++Fin de cycle
if((digitalRead(B1)==1)&&digitalRead(S2)==0&&digitalRead(S3)==0&&digitalRead(S4)==0){
Mode1=0;
}
}
*/
//+++++++++++++++++++++++++++++++++++++++++++++++++Sécurité cours de traitement
if(digitalRead(H1)==1){
digitalWrite(SORTIE_Lampe2, 0);
digitalWrite(SORTIE_Lampe3, 0);
digitalWrite(SORTIE_Lampe4, 0);
}
if(digitalRead(H2)==1){
digitalWrite(SORTIE_Lampe1, 0);
digitalWrite(SORTIE_Lampe3, 0);
digitalWrite(SORTIE_Lampe4, 0);
}
if(digitalRead(H3)==1){
digitalWrite(SORTIE_Lampe1, 0);
digitalWrite(SORTIE_Lampe2, 0);
digitalWrite(SORTIE_Lampe4, 0);
}
if(digitalRead(H4)==1){
digitalWrite(SORTIE_Lampe1, 0);
digitalWrite(SORTIE_Lampe2, 0);
digitalWrite(SORTIE_Lampe3, 0);
}
//+++++++++++++++++++++++++++++++++++++++++++++++++Création des Modes
int Mode1;
if(digitalRead(S1)==1&&digitalRead(S2)==0&&digitalRead(S3)==0&&digitalRead(S4)==0){
Mode1=1;
}
int Mode2;
if(digitalRead(S2)==1&&digitalRead(S1)==0&&digitalRead(S3)==0&&digitalRead(S4)==0){
Mode2=1;
}
int Mode3;
if(digitalRead(S3)==1&&digitalRead(S1)==0&&digitalRead(S2)==0&&digitalRead(S4)==0){
Mode3=1;
}
int Mode4;
if(digitalRead(S4)==1&&digitalRead(S1)==0&&digitalRead(S2)==0&&digitalRead(S3)==0){
Mode4=1;
}
//+++++++++++++++++++++++++++++++++++++++++++++++++Création des Modes_H
int ModeH1;
if(digitalRead(H1)==1&&digitalRead(H2)==0&&digitalRead(H3)==0&&digitalRead(H4)==0){
ModeH1=1;
}
int ModeH2;
if(digitalRead(H1)==1&&digitalRead(H2)==0&&digitalRead(H3)==0&&digitalRead(H4)==0){
ModeH1=1;
}
int ModeH3;
if(digitalRead(H1)==1&&digitalRead(H2)==0&&digitalRead(H3)==0&&digitalRead(H4)==0){
ModeH1=1;
}
int ModeH4;
if(digitalRead(H1)==1&&digitalRead(H2)==0&&digitalRead(H3)==0&&digitalRead(H4)==0){
ModeH1=1;
}
//+++++++++++++++++++++++++++++++++++++++++++++++++Envoyer la pièce vers la position 1
//if(Mode1==1&&(digitalRead(B4)==1||digitalRead(B2)==1||digitalRead(B3)==1)&&ModeH1==1)----------------->>>> ceci au lieu de ca en-bas.Histoire de le rendre plus legé
if(digitalRead(S1)==1&&digitalRead(S2)==0&&digitalRead(S3)==0&&digitalRead(S4)==0&&(digitalRead(B4)==1||digitalRead(B2)==1||digitalRead(B3)==1)&&digitalRead(H2)==0){
digitalWrite(SORTIE_Relais_AR, 1);
digitalWrite(SORTIE_Lampe1, 1);
}
// Fin du cycle
if((digitalRead(B1)==1)&&(digitalRead(H1)==1)&&digitalRead(S2)==0&&digitalRead(S3)==0&&digitalRead(S4)==0){
digitalWrite(SORTIE_Relais_AR, 0);
digitalWrite(SORTIE_Lampe1, 0);
}
//+++++++++++++++++++++++++++++++++++++++++++++++++Envoyer la pièce vers la position 2
//Marche arriere
if(digitalRead(S2)==1&&digitalRead(S1)==0&&digitalRead(S3)==0&&digitalRead(S4)==0&&(digitalRead(B4)==1||digitalRead(B3)==1)&&digitalRead(H1)==0){
digitalWrite(SORTIE_Relais_AR, 1);
digitalWrite(SORTIE_Lampe2, 1);
}
//Marche avant
if(digitalRead(S2)==1&&digitalRead(S1)==0&&digitalRead(S3)==0&&digitalRead(S4)==0&&digitalRead(B1)==1&&digitalRead(H1)==0){
digitalWrite(SORTIE_Relais_AV, 1);
digitalWrite(SORTIE_Lampe2, 1);
}
// Fin du cycle :
if((digitalRead(B2)==1)&&(digitalRead(H2)==1)&&digitalRead(S1)==0&&digitalRead(S3)==0&&digitalRead(S4)==0){
digitalWrite(SORTIE_Relais_AR, 0);
digitalWrite(SORTIE_Relais_AV, 0);
digitalWrite(SORTIE_Lampe2, 0);
}
//+++++++++++++++++++++++++++++++++++++++++++++++++Envoyer la pièce vers la position 3
//Marche arriere
if(digitalRead(S3)==1&&digitalRead(S1)==0&&digitalRead(S2)==0&&digitalRead(S4)==0&&(digitalRead(B4)==1)&&digitalRead(H2)==0){
digitalWrite(SORTIE_Relais_AR, 1);
digitalWrite(SORTIE_Lampe3, 1);
}
//Marche avant
if(digitalRead(S3)==1&&digitalRead(S1)==0&&digitalRead(S2)==0&&digitalRead(S4)==0&&(digitalRead(B1)==1||digitalRead(B2)==1)&&digitalRead(H2)==0){
digitalWrite(SORTIE_Relais_AV, 1);
digitalWrite(SORTIE_Lampe3, 1);
}
// Fin du cycle
if((digitalRead(B3)==1)&&(digitalRead(H3)==1)&&digitalRead(S1)==0&&digitalRead(S2)==0&&digitalRead(S4)==0){
digitalWrite(SORTIE_Relais_AR, 0);
digitalWrite(SORTIE_Lampe3, 0);
}
/*
//+++++++++++++++++++++++++++++++++++++++++++++++++Envoyer la pièce vers la position 4
//Marche arriere
if(digitalRead(S4)==1&&digitalRead(S1)==0&&&&digitalRead(S2)==0&&&&digitalRead(S3)==0&&(digitalRead(B4)==1||digitalRead(B2)==1||digitalRead(B3)==1)&&digitalRead(H2)==0){
digitalWrite(SORTIE_Relais_AR, 1);
digitalWrite(SORTIE_Lampe4, 1);
}
// Fin du cycle
if((digitalRead(B4)==1)&&(digitalRead(H4)==1)&&digitalRead(S1)==0&&digitalRead(S2)==0&&digitalRead(S3)==0){
digitalWrite(SORTIE_Relais_AR, 0);
digitalWrite(SORTIE_Relais_AV, 0);
digitalWrite(SORTIE_Lampe4, 0);
}
*/
}
.