Step 6: Thread wires through tube
Identify the wires at the other end and label them now, because, once the sensor is fixed inside, it is virtually impossible to tell them apart. It would be a good idea to measure and make sure no short circuits exist.
Using the diode check range of the multimeter, the three leads will either show 'open' or as a diode. A reading of zero ohms should be cause for consternation.