[doobedoobedo]

It's not a current sensor. It's almost certainly a contactor.

https://na.industrial.panasonic.com...panasonic_aev_ev_new_product_introduction.pdf

It's probably a special part for Nissan. There is some speculation as to it's specs here

 

[doobedoobedo]

You should be able to find out fairly easily all those linked are linear, so supply power and measure the output voltage with no current to get the offset, then pass a variety of known currents through to get the slope. All the known currents should plot on a straight line if it's anything like the rest of the range.