So I'm in the middle of swapping my km-145 to a v5m21 so far everything is going good just have a question about a 4th sensor it's on the transfer case driver side I've found it's called a pulse generator. My km-145 only had three originally reverse hi and low. Was this a fail safe switch of some sort or just a speed sensor of some sort? Best I can tell it shouldn't mess with the operation of the transfer case it just reads that its spinning.