problem with voltage levels. RS232
Thank you very much, you could be right, I was not thinking about this problem.
I opend the gps box and i found this chip: Sipex Corporation SP385EET datasheet pdf
my tx and rx cables are connected to his pins 9 and 8 so I thought to solder 2 cables to pins 12 and 13 of that chip to catch the ttl levels as you can see in the datasheet. We will see if I will be lucky.
Thank you again PaulS.