SR Wiring using FRSPort's Guide

[whiplash willy]

I have read through FRSport's guide and had a few questions I have been unable to answer.

1. Will this guide work for all flavors of S13 and S13 SR20dets? For example, will it work for putting a 98 S13 Blacktop engine into a 90 auto?

2. I hear that even if you go through this guide, there are some additional wires that need to be lenthened in order for the harness to fit properly. They say you can make it fit without leghtening any additonal wires, but you have to pull and twist the harness into place, which is very sloppy.

Thanks!

[SpeedRacer1]

The wiring harness of a 1998 engine is different but the specific parts that get spliced/repinned into the 240SX wiring should be the same. Except the fuel pump wire may be black/red instead of black/pink(purple).

Lengthen the: MAFS, O2 wiring, PS pressure sensor, AC (last two unnecessary if you dont use them)

[whiplash willy]

Thanks SpeedRacer1,

What do you use to find which color wire does what. It looks like there are a bunch of wires I don't have to hook up when i splice the plugs into the harness, I just want to know what Im not hooking up. The wiring diagram on my FSM doesn't show wire colors.

Also,

What does the PS pressure sensor do?

[SpeedRacer1]

Usually the stuff that is not hooled up is related to: AC, Ambiant temp, Nissan Consult signals, etc.

PS pressure is used to increase the idle when the PS is under higher pressure. For example, turn the steering wheel left or right when you are not moving and the idle goes up. It is a fairly useless sensor on the SR's most people do not use it.

[whiplash willy]

I am working on the dash connector end, there are 3 black wires on the SR harness and 1 black on the KA side. Do i just solder all of them together?
Modified by whiplash willy at 12:32 PM 2/19/2007

[whiplash willy]

My car used to be an auto and was swapped to manual before I got my SR. I jumpered the plug on the lower engine harness to make the ECU think its in auto all of the time. I plan on using my KA lower enigne harness. Since I am using the SR's ECU, will it still think its in auto, or do I need to do something with the neutral safety switch for my car to start?

[whiplash willy]

I am working on the dash connector end, there are 3 black wires on the SR harness and 1 black on the KA side. Do i just solder all of them together?

[SpeedRacer1]

Honostly, the black wire on the KA harness leads to nothing. I found this out when I redid my wiring one of the many times. It goes to the cosult if i recall. So even if you splice the three black wires together with the KA wire nothing should happen. If it turns out you are having issues with the car later just ground those three wires on the chassis.

The neutral position switch tells the ECU when the car is not in neutral and does not allow the cat to be started. If it is left disconnected the ECU ignores the neutral switch and assumes the shifter is in neutral at startup. I wouldnt worry about that sensor.

[whiplash willy]

Thanks for all of the help so far, I just want to be 100% clear here. I have no idea where the actual transmission neutral switch is. I assume it is in the transmission, but since I am using the KA lower harness, it should't be hooked up. I did splice the transmission neutral switch in my wiring harness which the FRSport and Heavy throttle guide say to do.

SR Wire Color KA Wire Color FunctionGreen / Orange stripe Green / Orange stripe Transmission neutral switch

So will splicing this wire cause my car not to start? Where is this sensor at so I make sure not to plug it in?

[SpeedRacer1]

The car should start without the neutral position sensor installed/spliced. It is the green with orange stripe wire on the KA harness.

On the SR transmission there should be 3 sensors. The one closest to the front is the reverse sensor, you might want this so that your reverse lights turn on. The one in the very back is the speed sensor, needed for the speedo to work. The neutral position sensor is the middle sensor if you wanted to know what that was.

[whiplash willy]

I am having a tough time finding a sutible wire to extend the large white wire on the O2 sensor. The guide I am using says I need to use shielded wiring. What kind of shielding do I need? Do I really need shielded wire for this?

[leroiboy]

don't mean to jack this thread but, gotta ask speedracer something. my sr harness is cut in one spot which is where it goes throught the drivers side fender into the car. do i just cut my ka harness in the same spot as well and splice into it? if so, is it wire for wire or how do i go about doing this? thanks for anyhelp.

p.s.-anyone can help, but i just asked speedracer since he was on this thread

[SpeedRacer1]

I am having a tough time finding a sutible wire to extend the large white wire on the O2 sensor. The guide I am using says I need to use shielded wiring. What kind of shielding do I need? Do I really need shielded wire for this?

The shielded wire is merely a wire with more wire outside of it that is grounded so that other frequencies dont interfere with the sensitive signal of the sensor. The MAFS and O2 sensor require shielded wire in order to work properly. Will the sensors work ok without the shielded wire yes, but there is a chance it can have odd effects to the sensor voltage. Try to get some shielded wire if possible.

don't mean to jack this thread but, gotta ask speedracer something. my sr harness is cut in one spot which is where it goes throught the drivers side fender into the car. do i just cut my ka harness in the same spot as well and splice into it? if so, is it wire for wire or how do i go about doing this? thanks for anyhelp.

p.s.-anyone can help, but i just asked speedracer since he was on this thread

I assume you are talking about the wiring up by the battery. If so you can cut the KA harness and splice in the SR harness. I would recommend you use the KA connectors still so that the harness can be removed easier if necessary. Not all the wire colors will match up but the necessay ones for the swap should, here is heavy throttle's old diagram on which wires to splice.

[whiplash willy]

I have called every electronic store in my area, either they don't carry shielded wiring, or they only sell it in huge bulk quantiles. Can I use the shielded wiring in my SOHC harness O2?

[SpeedRacer1]

Absolutely.

[whiplash willy]

I followed the guide exactly, and my car started up the first time. Truly a great guide. Everything works now. There are 2 water temp sensors on your intake manifold. 2-wire is the temp sensor for the ECU and 1-wire is for your gauge cluster. You have to switch the gauge temp sensor (1-wire) with the one that corresponds with your gauge cluster. I used my SOHC cluster so I had to switch to the SOHC gauge Temp sensor.

[leroiboy]

ok, heere goes another question. should i use the sr20det car harness or my ka24e car harness? i have had the sr engine harness rewired and converted and is on its way back to me. thanks for any insight

[SpeedRacer1]

When you do an SR swap you use the SR inner engine harness that goes from ECU to engine. You use the KA outer engine harness, fuseboxes, etc. You can choose to use either the KA or SR lower engine/transmission harness, they are quite similar.