Throttle Sensor??

I have a 13 merc 250xs, the sensor in my throttle assembly wasnt telling my motor its in nuetral therefore it wouldnt let allow me to start it .. ordered new throttle assembly and as soon as i hooked the 2 yellow wires up my motor turned over. a week later is did the same thing. Anyone ever had this problem? is there a way to bypass the sensor? they said you could wire the to yellow wires and it would bypass it, but that didnt work. any help whould be greatly appreciated.