int pirSensor = 4;
int led = 2;

void setup() {
  pinMode(pirSensor, INPUT);
  pinMode(led, OUTPUT);  
}

void loop() {
  int sensorValue = digitalRead(pirSensor);

  if (sensorValue == 1) {
    digitalWrite(led, HIGH); // The Relay Input works Inversly
    delay(200);
  }
  
  else {
    digitalWrite(led, LOW);
    delay(200);
  }
}