It isn't adam. TXS knocklite needs a 12v feed, the actual knock sensor doesn't. Knocklite needs an rpm signal, knock signal (if you want to use it for that purpose, my knocklite is only functioning as a shiftlight atm as the knock sensor location i was using was shit and was too noisy to be accurate), knock sensor ground (from the sensor) and earth.
1 wire on the sensor is earth, the other is the knock signal wire. because knock sensors operate on the piezo electric principal, they generate their own very small voltages as an output to an ecu/knocklite where the device receiving the knock feed amplifies it to make it a usuable signal.