"Same situation here i am shifting to turnigy esc for time being but i had put a voltege divider between esc and pixhawk but it still didnt worked
probably your explanation is right."
"i also checked with the power coming from 5v BEC but again the result was same i was thinking to put a voltage divider circuit infront of the pixhawk o/p to convert it to 5v peak to peak."
"the only difference that i could find between pixhawk o/p and receiver o/p is that the peak to peak voltage of pwm given by pixhawk is 7v where as for receiver it is 5v"
"i think pixhawk sends the signals using ppm but the esc is not able to read them properly. probably the calibration for ppm is different i will have to check with a oscilloscope."