RB25 Unknown Engine Harness Plugs

[Jboogsthethug]

Hoping someone can help! I'm almost done with swapping the RB25 in and I'm at a loss for a few of the plugs on the harness. My guess is they go to things that I don't have connected but I'm hoping for clarification!

Here are the pics:

First: this is coming off the alternator, my guess was maybe the fans or something?




There's s 3 way split where the MAF and the Exhaust sensor lines split off with this last guy.


This 6 hole plug close to where the harness comes out of the firewall. Before the injector plug.



This 8 hole plug that comes directly from the firewall split.



These two cylinder shaped pieces, not sure.





Any insights? Eventually I plan on taking the harness out and removing things like this that aren't needed but I want to get it running first. I'm guessing one of these go to the transmission as there are a few plugs down there that I'm not sure where they end up. 

[Jboogsthethug]

Looking at https://www.wiringspecialties.com/rb25det3.html?sort=featured&page=2 May answer some of my questions.

I think this is a wastegate connector or the speed sensor? 

Wastegate: https://www.wiringspecialties.com/connectorj.html

Speed: https://www.wiringspecialties.com/rbspseco.html



And that's about it ha. ANy confirmation on this?

[wrcbonk]

Hey,

 

I have not checked the forum in a while. Just now seeing your post. Did you get your RB started?

 

Bill

[Jboogsthethug]

On 9/11/2021 at 5:01 AM, wrcbonk said:

Hey,

 

I have not checked the forum in a while. Just now seeing your post. Did you get your RB started?

 

Bill

Unfortunately not yet. I've been focusing on getting a few house projects finished. Moving forward I attached everything I could find a port for and I'll try to start it and just see what codes pop up. I'm thinking they are things that were deleted by the engine's PO but I'll find out for sure at that point. Once I get it narrowed down I plan on marking the unused ports and then rebuilding the harness to fit correctly while also getting rid of any excess plugs.

[mtnickel]

This might explain a few of them.

 

This guide is old and verbose and not great, but could help.

https://www.dropbox.com/s/bwjujmf4ixtzmhb/Final RB Guide Draft 4.docx?dl=0

 

If you're using the stock ECU, I have a nistune setup if you're wanting to tune it.

 

You are going down the right track as far as stripping the harness to make things fit...especially if you are converting to the Greddy style manifold. I originally just tapped into wires needed and bundled everything else up, but I got fed up with the mess after a while and did as you said. It was quite the rats nest, but I stripped the harness to whats needed and cut out all the excess.

 

Some of the big spade plugs were deleted completely once sorted

 

What gen is your RB25?

[Jboogsthethug]

On 10/20/2021 at 3:47 PM, mtnickel said:

This might explain a few of them.

 

This guide is old and verbose and not great, but could help.

https://www.dropbox.com/s/bwjujmf4ixtzmhb/Final RB Guide Draft 4.docx?dl=0

 

If you're using the stock ECU, I have a nistune setup if you're wanting to tune it.

 

You are going down the right track as far as stripping the harness to make things fit...especially if you are converting to the Greddy style manifold. I originally just tapped into wires needed and bundled everything else up, but I got fed up with the mess after a while and did as you said. It was quite the rats nest, but I stripped the harness to whats needed and cut out all the excess.

 

Some of the big spade plugs were deleted completely once sorted

 

What gen is your RB25?

Thanks for sharing that link, that may prove to be super helpful!

As far as the ECU, it is the stock ECU but I plan on upgrading at some point so no worries.

And unfortunately I'm not sure. It was pulled from a 240sx and has had all the identifying parts (that I know of) replaced with aftermarket parts. But I figure at that point it doesn't really matter regardless, does it?