rb25 wiring help

[keith]

I'll start out by saying if anyone has an uncut rb25 series 2 harness, pm me a price, it not, this is my issue...

My harness, the part inside the car, has all the plugs cut off except the ecu plug, colors don't appear to be the same on my rb20 harness to switch the plugs over, anyone have any experience in doing this? Thanks

[RR32GTRR]

I'll start out by saying if anyone has an uncut rb25 series 2 harness, pm me a price, it not, this is my issue...

My harness, the part inside the car, has all the plugs cut off except the ecu plug, colors don't appear to be the same on my rb20 harness to switch the plugs over, anyone have any experience in doing this? Thanks

The R32 has 4 plugs that go into the chassis. 1 goes to the fuse box inside the engine bay and 3 near the ecu for the dash plugs and wiper. The R33 however has the fuse box in the back and has 1 big plug for the fuse box and the the dash plugs. Kiinda like the s13 and the s14.

The easiest thing to do here is make a hybrid Rb20/25 harness. What this means is use you rb20 harness but wire in the rb25 injector harness, rb25 or 20 igniter and coils, rb25 vct, and since you have a s2 you will have to mod tou throttle body harness.

[keith]

but will a r33 rb25 power fc work properly with a rb20 harness?i was told before it wouldnt so thats y i wanted to do the r33 harness, thanks

[jdms13rhd]

when I do rb25 swaps in R32's I always use the RB25 harness and sensors. When you swap that S2 harness for a R32 you dont need any of those plugs anyways. You just need to hard wire your dash/cluster wires and fuel pump ect. I normally cut off the plug from an R32 harness so that I can pin them into it so the 25 harness plugs into the R32 Dash plug. All you need is a ecu pin out to figure most of it out then track down the wires for your temp sensor, tacho, fuel pump ect. easy as pie. So with that said, dont waste your money on another harness. once you get into it you will understand. You just need to wire it up from in the front pass side of the engine bay like the 32 harnesses. Its like 2 wires and she will run. Then splice the lower batt harness with the origonal R32 lower batt harness to make it all work. I think its just the knock sensors and oil pressure sw in the 25 harness you keep and the 32 harness still drives the starter and alt and trans stuff.

[keith]

ok, i have both harnesses outside the car now, i looked at them, remembered how much i hated wiring, and then came here, lol, ill look for some pinouts and try to get this done then, thanks for the input

[RR32GTRR]

but will a r33 rb25 power fc work properly with a rb20 harness?i was told before it wouldnt so thats y i wanted to do the r33 harness, thanks

Ya. it will. The Rb25 and 20 have the exact same pinouts minus the vct and injectors 6 and 4.

[jdms13rhd]

Ya. it will. The Rb25 and 20 have the exact same pinouts minus the vct and injectors 6 and 4.

The main reason I dont like using the 32 harness is cuz then you have to use the 32 coils and some sensors. Theyre old and, well theyre old. Since you got the S2 everything would look much nicer with the newer coils in there. Sure you can mod it to work but then thats a job on its own. Plus, one less wire to power up the ecu and injectors. The harness on a rb25 is just a more clean, more advances harness with newer bits that are not breaking.

For the easy, fast way, use the 20 harness by all means. It will get it running easy enough with very little work.

[keith]

well.. i sold my rb20 with coils and everything on it, so looks like im going to use the rb25 harness, thanks

[jdms13rhd]

well.. i sold my rb20 with coils and everything on it, so looks like im going to use the rb25 harness, thanks

Thats good. Better way to do it imo

[keith]

well, i have most of the wiring done, theres a couple spots i have to look into a little more

1- rb20 didnt have a wiper module? i have wires running to that instead of going into the dash plugin
2- the loom that comes off the side of the main part of the harness is cut off (one that goes to o2 and other plugs around it)
does anyone know what wires go to which plugins? i believe i have the maf and 02 part figured out, but im not sure of the others

thanks!

[jdms13rhd]

1:strip the wiper harness out of the R32 engine harness. Its attached by one or two wires inside the 32 harness. I think it just gives it power. you can find out what to do with a little messing around with your ohm meter. I think the car end has 8 wires and the wiper motor end has something like 6 wires. Ther are 5 wires for the wiper switch, one ground and then two wires that are inside the harness that you will have to pin out to find what to give it. Pretty sure it gets its power from the power up plug that powers the harness inside the engine bay. Probe that plug with the 32 harness to figure out what those wires will be for.

2: That part, you needed. Since its gone you will have to add that part. What I normally do anyways, is strip the rb25 harness from the engine bay on the firewall section to the ecu. Anything missing, you can add in, loom up, tape, done. If you have a pin out you can use that to find out what cut wires are what. If its not for AC, maf, o2, power steering, you can just leave it out. there are a few things in rb harness that are for emissions ect and you dont really need them. when I do RB harness, they are pretty bare when I am done.

[keith]

well, the car runs, the problem is it runs on 3 cylinders? lol, anyone know what i messed up?

[keith]

as random as it is... i had 3 bad injectors... lol

new problem, is the rb25 s2 maf the same as the rb20? from searching i found that the s1 and rb20 are the same, but didnt find much about the series 2... does anyone have one if not?

[keith]

also im not getting a reading from my coolant temp sensor, would that put it in limp mode as well?

[RHDskyline]

rb25det series 1 going into a rb20det powered cefiro


use rb20 harness and just switch over the injector clips from the 25 harness over?

or else it looks like it will be a hell of a time cause all the body clips on the 20 harness and the 25 harness has none.

i was told this is the easiest way.

just solder all the 25 injector clips on the 20 harness, swtich the two pins for the ecu and you are on yours way