Help, Extruder Wiring Please

I'm in the process of installing a new extruder head but have no idea which wires to connect to. The stock wires are all either both red or both white. I need to know which ones are positive and negative so I can hook up the smaller sensor wires (I am re using the bigger sensor wires so only the small ones need to be figured out). Attached image of wires I am specifically referring to. Many thanks.

 

So I ended up just guessing and it turns out I was correct the first time. The negative terminal for the thermistor is on the outside and the positive wire goes on the inside, next to the heater wires

 

Red,
The thermistor and the heater have no polarity. They both are just resistors.

 

Well there you have it! Seems odd that my new thermistor would have positive and negative colored cables then...

 

Are you using an NTC thermistor like the E3D stock Semitec 104GT2? These operate as simple temperature dependent resistors. Perhaps you have something more unusual that depends on the direction of the current?