wiring a rb20 into s14

Post by **ibzbro** » Mon Jun 14, 2004 10:33 am

hey i searched but i could not find anything for a complete wiring swap for a rb20 in an s14. i have done a couple of rb20 into s13s but never into a s14. is it pretty close? is there a 8step wiring guide like with the s13? any help would be great.

Post by **eh?** » Mon Jun 14, 2004 10:33 am

check my site under specs and tech. It's made by wulfgang and he did post here a while ago.

Post by **Wulfgang** » Mon Jun 14, 2004 10:33 am

Heh... You searched? Really??? I just searched using your subject "wiring a rb20 into s14" and found several links with all the info you need.

Don't give up so easily. The truth is out there.

Post by **ibzbro** » Mon Jun 14, 2004 10:33 am

if you talking about this site then yes i have seen it. https://netfiles.uiuc.edu/dsta...s.pdf

but it is very hard to read and make any sense of. i love looking at wiring dirgrams but this is too hard. it is like only half of the wiring, i mean know one has done a step by step?

Post by **goofynick6** » Mon Jun 14, 2004 10:33 am

yeah, I wish there was a step by step, because right now I'm sitting with a big wiring harness and a bunch of cut wires and a clueless look on my face..heh.

Nick

Post by **fadeds14** » Mon Jun 14, 2004 10:33 am

well it might be a little confusing at first but if you foolow that and understand it it works i used thatb and my s14rb20det purrs like a kitten

Post by **Nameless EJ6** » Mon Jun 14, 2004 10:33 am

ibzbro wrote:but it is very hard to read and make any sense of. i love looking at wiring dirgrams but this is too hard. it is like only half of the wiring, i mean know one has done a step by step?

Maybe you should be the first to do a step by step.

I'll be doing it with the RB26 into S13 in a couple months.

Post by **goofynick6** » Mon Jun 14, 2004 10:33 am

Yeah I just looked at the writeup in that link, and it is kinda confusing, because it tells you what each wire does on the ecu that is important, but then the 'connection to 240sx' part is confusing...is it meaning connection to a stock harness or what?

Nick

Post by **ibzbro** » Mon Jun 14, 2004 10:33 am

i know that is what i was thinking. but for this swap i will be doing a step by step including how to do the gauge cluster.

Post by **Wulfgang** » Mon Jun 14, 2004 10:33 am

Could you clarify your questions? I can make changes if things are confusing, but I thought it was pretty much a "step-by-step."

On the side that says "Plug on RB20DET", you just find the plug that matches the shape and wire colors on the R32 engine harness.

On the side that says "Connection to 1995 240SX" you find the wire that goes into the F3 connector and splice it in. Basically, you use the F3 connector that was on your S14 engine harness and splice in the R32 wires there. You *could* cut your F3 connector totally off and then reconnect it to the R32 harness, but I preferred to leave things like the wipers and cruise still connected.

Once you have made the splices, you'll have an R32 harness with an F3 connector on it. This is ALL you need. No other connections are necessary. Just put your R32 wiring harness (now with F3) and ECU into your car and plug in the F3 where it went before.

Take your time and do this right and you'll have a harness that looks and functions just like the stock S14 harness. There are no special tricks except for the ECU powering scheme I mentioned (which I used - it does work).

Post by **goofynick6** » Mon Jun 14, 2004 10:33 am

Ok, sorry to be stupid here, but I'll try to get some clear questions.

What is an F3 connector?

Do I cut anything off the R32 harness?

you said "find the wire that goes into the F3 connector and splice it in.... what "wire(s)" are you referring to? The only think should be spliced would involve power or ground or something right?

Here are some pics, feel free to refer to them!

Whole R32 Harnesshttp://filebox.vt.edu/users/ni...7.JPG

Up close of plug that goes into ecu (are there supposed to be this many pieces of tape and stuff in there?)http://filebox.vt.edu/users/ni...6.JPG

On another note, this box was where the clutch pedal now goes (used to be automatic), now it doesn't fit, so is this for the auto trans?)http://filebox.vt.edu/users/ni...1.JPG

Thanks!! My project is moving faster than I thought, so I need to know my wiring soon.

Nick

Post by **lyon23** » Mon Jun 14, 2004 10:33 am

thanks to wulfgang i do have an rb20 in a s14.. if i'm not mistaking the f3 connector he's talking about is the white plug that is behind the stock s14 computer that has all your wiring connections on it. I separated the wires that come from the ecu and the other engine items like cruise, wiper, and speedometer and I cut the ones going to the ecu and connected the rb wires to it. I put the rb plug that has the red/black, white/blakc and white/purple wires inside the car and connect them in the wires that were left from when I cut the ecu wires.

I dont think there should be tape on ur harness that close to the ecu but I think they had somehting hook up to it, mine looked like it had a tach on it.

Post by **goofynick6** » Mon Jun 14, 2004 10:33 am

lyon23 wrote:thanks to wulfgang i do have an rb20 in a s14.. if i'm not mistaking the f3 connector he's talking about is the white plug that is behind the stock s14 computer that has all your wiring connections on it. I separated the wires that come from the ecu and the other engine items like cruise, wiper, and speedometer and I cut the ones going to the ecu and connected the rb wires to it. I put the rb plug that has the red/black, white/blakc and white/purple wires inside the car and connect them in the wires that were left from when I cut the ecu wires.

I dont think there should be tape on ur harness that close to the ecu but I think they had somehting hook up to it, mine looked like it had a tach on it.

You used the word ecu a lot in there, but didn't specify r32 or s14 so I am still confused.

What are we doing by splicing into this F3 connector?

Thanks

Post by **lyon23** » Mon Jun 14, 2004 10:33 am

in this case the ecu's are for the s14. the only ecu for the rb20 is at the end the one that talks about the tape.... sorry for the confussion

Post by **goofynick6** » Mon Jun 14, 2004 10:33 am

Ok, I'm starting to understand a little more on that part, so you have to pull the smaller harness that goes thru the firewall from the larger one and keep it. Then the larger harness that goes to the KA is take out right?

Sorry for so many questions, but this is quite a task for me..heh.

Nick

Post by **lyon23** » Mon Jun 14, 2004 10:33 am

thats right the harness that went with the ka I took out. I passed bothe the ka harness and the f3 connector out to te engine bay and separate it from there then after I cut the ka harness from the f3 connector I passed the f3 back in the car.

Post by **Wulfgang** » Mon Jun 14, 2004 10:33 am

After you've pulled your engine harnesses and engines out, it helps to put them side-by-side on the floor and look at the harnesses. You need to make the RB harness look like the KA harness. The F3 connector will need to come out of the RB harness about 10" from the ECU connector, with about a 6" connection. When I get some time, I'll try to make a diagram (from memory... I don't think I took pics of that part).

Post by **goofynick6** » Mon Jun 14, 2004 10:33 am

So you remove the F3 from the RB harness and splice in the F3 from the KA...I'm getting closer and closer. I'm heading back to the garage to separate them.

Nick

Post by **Wulfgang** » Mon Jun 14, 2004 10:33 am

No, there is no F3 on the RB. There are several other plugs on the RB harness that will all be combined into the F3 plug that was on the S14.

The RB uses the O, P, and Q plugs to do such things as deliver power from the battery, run the gauge cluster, etc. On the other hand, the S14 uses the single F3 plug to do everything external to the harness (tach, power lines, tranny switches, A/C lines, PS switch, etc.).

What you have to do is combine the RB O, P, and Q plugs and run those wires into the F3 connector. Since the S14 also runs the wiper and cruise through the engine harness and F3 plug, you will have to keep those wires.

I'm working on some diagrams....

Post by **goofynick6** » Mon Jun 14, 2004 10:33 am

Thanks

Post by **Wulfgang** » Mon Jun 14, 2004 10:33 am

Ok, here's 1 step short of a step-by-step guide. If a picture is worth a thousand words, then here's 3000 words:

https://netfiles.uiuc.edu/dstaffor/www/ ... _guide.pdf

Two new pages at the bottom, so be sure to scroll down.

"eh?" feel free to update your link on rb25det.org.

Post by **goofynick6** » Mon Jun 14, 2004 10:33 am

Haha, you rock! That diagram is super nice!

The best part is, I spent 3 hours today playing with harnesses and I got it 90% figured out, but the diagram gives me the other 10% I needed.

Just so people know, there was an ECU pinout from rb20det.org or somewhere what I once posted, and I used it today and it has a typo, pin 43 and 53 are switched, so i accidentally cut the ignition control wire isntead of VSS..whoops.

Here are some pics for reference:

KA F3 Plug and wiper/ASCD plugs

R32 Harness with important plugs

Post by **goofynick6** » Mon Jun 14, 2004 10:33 am

Quick question, does the RB20 only use the o2 sensor on downpipe? Because I have the other one near the cat from the s14 harness and wasn't sure if it'll do anything.

Thanks

Post by **Wulfgang** » Mon Jun 14, 2004 10:33 am

Just the front O2 for the RB20. The rear O2 sensor on the KA just tells you when your cat has gone bad.

Post by **goofynick6** » Mon Jun 14, 2004 10:33 am

Thanks.

I did the whole wiring thing today, and I got the harness all reinstalled, every connection was soldered and wrapped

...however, there's a few questions I have left (small details)

Ok, on the "O" plug, the last line of connections, "H", on the connection to S14 side, it says "should wire separately to F3 (17) and F3(1) -- Wire ECU backup power to 17 and all others to 1

That saying connect H to 17 and E and F to 1?

Also, when I was done there was a LOT of leftover cut wires from the F3 plug..is that OK? There were 3 black wires especially that I wondered if they needed grounds?

Also, this picture is of a plug that goes RIGHT beside the F3 plug with the s14 harness...is it no longer needed?http://filebox.vt.edu/users/ni...2.JPG

And a small pic of my finished harness (looks oem)http://filebox.vt.edu/users/ni...s.JPG

Thanks again, I couldn't have done it w/o everyone's help.

Nick

Post by **BoostFab** » Mon Jun 14, 2004 10:33 am

I will start my swap this weekend, but it's going into a 91 S13. your diagram is definately a good start and clear up some confusion. Wulfgang; thanks for all your input and contribution.

Post by **Wulfgang** » Mon Jun 14, 2004 10:33 am

goofynick6 wrote:Ok, on the "O" plug, the last line of connections, "H", on the connection to S14 side, it says "should wire separately to F3 (17) and F3(1) -- Wire ECU backup power to 17 and all others to 1

That saying connect H to 17 and E and F to 1?

We had a thread about this a while back, and many people do not think it is necessary to separate these. The RB has the ignition coil relay (and thus the coils) and the injectors high sides (+) wired directly the the battery ("constant power"). These wires carry a lot more current than, say, the wire that provides backup power to the ECU.

However, on the S14 KA the coil and injectors are wired to the ignition switch, and only turn on when your ignition is turned to ON. This is an inherently safer design, since neither the injectors nor the coils can possibly have voltage if your engine is switched off.

So on your S14, the F3(1) wire was designed to carry all of that current, and as you have seen, it is a big wire. The ECU backup power wire (constant power) is F3(17) and is about a 22 gauge wire. You could route your RB injectors and coil relay power through this wire to keep the constant power setup that the R32 had, but F3(17) is hopelessly small for that kind of current. If you feel the need to do it this way, then you should probably fit a new, 14 gauge fused wire for the job.

In my opinion, it is better to keep it the KA way, splitting off the ECU backup wire and ECU relay signal side power and routing them to F3(17), while routing the other side of the ECU relay and the injectors and coil relay to F3(1).

Quote »Also, when I was done there was a LOT of leftover cut wires from the F3 plug..is that OK? There were 3 black wires especially that I wondered if they needed grounds?

Also, this picture is of a plug that goes RIGHT beside the F3 plug with the s14 harness...is it no longer needed?http://filebox.vt.edu/users/ni...2.JPG [/quote]

I have never seen this plug before. There were no plugs right beside the F3 on my car. Do you have ABS or an automatic?

As for the extra wires, you've got a few GST/CONSULT wires, the defogger signal, electric fan signals, ambient temp. sensor, 5th gear sensor, and a few additional A/C wires (such as recirc and part of the triple pressure switch) that the RB ECU doesn't care about. A pinout of the 1996 F3 can be found here to give you some idea of what is on that plug.

Post by **goofynick6** » Mon Jun 14, 2004 10:33 am

Hey, Thanks for the info...I did have an automatic, so that is probably what it was from. I guess I'll have to wait until I am trying to start the engine to find what I wired wrong..haha.

Nick

Post by **RBpower** » Mon Jun 14, 2004 10:33 am

Wolfgang, I'm still a little confused are you saying connect H to 17 and E and F to 1? Or do I connect H to 17 AND 1. By the way, I thank you for creating this guide.

Post by **goofynick6** » Mon Jun 14, 2004 10:33 am

That is what I did

...but then again I haven't started mine up or tried to..haha.

Nick

wiring a rb20 into s14

wiring a rb20 into s14

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