Ok! I found this:
Nissan Consult Port Pins
Use the above diagram as a reference. Splice each wire to the corresponding wires listed below.
SR20DET J2/J3/E4/E5 Pin Diagram
SR20DET J4/J5 Pin Diagram
Splice:
1) Rx wire (Receiver) to ECU’s Green wire with Black Stripe (pin 7)
3)Tx wire (Transmitter) to ECU’s Green wire (pin 15)
4) +12V wire (Power) to ECU’s Black wire with White Stripe (pin 38 or 47)
5) GND wire (Ground) to ECU’s Black wire (pin 39 or 48)
6) CLK wire to ECU’s Green wire with White Stripe (pin 14)
Software:
You can buy software to diagnose your engine (ie: Nissan Datascan, which is worth every penny, costs $100+), but there are free options available. Check out ECUtalk.