From your post I deduce that the sensor outputs on serial, and you've connected tx of module to tx of arduino, so the arduino can t see the data *since it's not directed to rx, and the data can only pass through to the serial adapter when the pin is tristated, by putting chip into reset state.
On serial, tx goes to rx (they stand for transmit and receive)
Doesn't change that you should have posted code and wiring, your explanation just has a huge red flag in it (that you get output with reset held down)