I have more information about this problem:

When I ignite the engine, I observe that the cluster red light for the AIRBAG, is blinking 4 or 5 times... I occurs when a passenger is on the passenger seat. I think it is working fine, isn't it??? I think, when nobody is seated on the passenger seat, the cluster red light for the AIRBAG doesn't blink, is it correct???

But, I don't know why sometimes I can ear a beep (short beep), five times (like beep, beep, beep, beep, beep)... What is this sound???????

Thank you in advance.
Regards