Thread: How to repin later OBDII ECU to work with early OBDII ECU

This is a guide i made to help people like me sort through which ECU terminals need to be swaped, deleted and added.

Essentially I made this for USDM 1999 P11 (G20) SR20DE and or 1998 B14 (Sentra/200SX) SR20DE owners with later style OBDII ECU's and wish to use an earlier style OBDII ECU which is compatable with a Nistune board etc etc (Im a Nistune user and have been since 2008).

Enjoy, this took me quite a while make, hope this helps you guys out and dont trust every OBDI and OBDII step down harness out there that think one size fits all cause they don't, it alot much easier to repin anyways.

Thanks the for info.

Your welcome

Nice info, but you do know this is on JWT site? and there is literally only like 3 wires you need to move to get it to work properly as I did it on my SE-L.

You rwelcome, JWT's write up on this doesnt cover it all, I do, cause im anal like that and yes it does make a difference. If you follow JWT yes your car will run but it wont run without some issues that wont even throw a cel light but you are right its very simple to do.

What kind of issues? I never had anything wrong besides the normal rear 02, egr becuase they were pulled. Never threw codes on the ecu as well when using my realtime to check them.

I was having voltage draw down issues at the TPS sensor and an overall lack of power until I removed the rear EVAP plug on the rear driverside of the vehicle and added a terminal to the crankshaft position sensor that is missing on the wiring harness of the P11 only, this is not missing on a 98 B14, thats probably the difference and like I said this one is specifically more detailed and tailored towards a 99 P11. The 98 B14 and 99 P11 are very similar but not the same exactly.

Also JWT says to swap pin 112 to pin 111, that is not correct you need to add a splice because pin 112 is still an active ECU ground and this ground also ground the coil.

And what else, two wires need to be added if you want the OBDII port on a P11 to work with a B14 ECU also.

Didn't Nistune start support OBD II ECU's in 2010?

Yea they did Nistune Forums • View topic - P11 Infiniti G20 I did a bit of leg work to get me an ECU that would work on my 99 P11, I would suggest to other though that they use a OBDII ECU for the 99P11 only because the crankshaft postion sensor circuit matches that of the 99 P11 ECU but its no big deal to splice in a wire if you use a B14 ecu also.

Hopefully soon he will be able to do the 1999 P11 ECU, I think I might send him my 1999 P11 ECU because last I asked him he said he didnt have one and he has hinted at it being very doable in some post IIRC, so I think theres hope