ok i just bought a 99 si harness and noticed that it only has 2 ecu plugs along with the green connector but my 99 ex harness has 3 ecu plugs along with the green connector. can i still use this even tho it has only 2 ecu plugs? i will be dropping a gsr into my 99 ex coupe. i have a obd2b jumper harness. will it still work?

 

bumppp

 

The third plug comes from under the dash. I was also scratching my head when I bought a si harness.

 

99-00 is OBD2b whereas 96-98 is OBD2a.. so you just need to use the engine harness, and plug it into your underdash(green plug).. obd2b is what you have so the jumper harness is cool.