My canadian obd2b harness is the 3 plug alt and my jdm b18c motor has the 4 round plug. I know I can re wire the 3 wires but theirs a 4th wire that's left out (alt controll) some people say it can be left un touched and it wont throw a cel some people say it needs to be wired into the ecu. So if it does have to be wired into the ecu which pin would it go into for a chipped p28? Has anyone left this wire and not thrown a cel? If so what ecu are you running?

 

Pic for reference