I searched but can't find an answer that is this basic. I know party of the wiring harness connects to the ecu. Where does the other part connect to? Why do people have to modify wiring harnesses like on a h22 in a prelude, can't you just use the prelude wiring harness and ecu or the original civic wiring harness and ecu? Or like putting a b16a2 in a 92-95 ex couldn't you just use the original p28 or the jdm ecu? Another question I have is what is the difference between obd0, obd1, and obd2? Why cant you put an obd0 in an obd1 car or and obd2 in a obd1 etc without modifications? I'm just confused on what happens to the ecu in swaps.

 

bump

 

obd o was the first i think 89-91 not sure
obd 1 was the 92 - 95
then obd 2 a and b
obd a was from 96-98
and obd b was 99 and up the higher the year the more sensors and the plugsfor the computer are all diff.

 

anymore imfo on this?