New Wiring Harness

For the past week I’ve been working on replacing my upper and lower wiring harnesses. While my original harness worked, there were a few items that I wanted to tidy up, and I always had a slight random hiccup with the vehicle. I could never determine if that was because of the AEM EMS not cooperating with my CAS wheel or if there was an electrical gremlin due to the hack job from an auto-5spd RB20 and then the RB25 swap.

I purchased a wiring harness with the ABS sub-harness and Auto->5spd from Wiring Specialties through RAW Brokerage. The harness arrived with an instruction manual, and it was super clean. All original plugs and wires, properly loomed, and basically ready to install.

They say this is a 15 minute job, and I think if you’ve done it a few times before then it quite possibly is a 15 minute job. My situation was a little different…

First I had to remove the original harness, which took longer than I had hoped, but that was simply because I was paying attention to where things were plugged in so that the install would be a bit easier. The original harness came off in about 30 minutes for me. pulling it through the firewall was surprisingly easy.

The new harness was a little more difficult. Various forums/posts on the internet suggest having two people work the harness plugs through the firewall and I can see why. That would have probably saved me 10-15 minutes easily because I had to keep going back and forth from under the dash to the engine bay to work the harness through. Where I started to run into trouble was matching up the plugs. Some of my OEM plugs have been removed, cut, spliced, changed, etc. and it wasn’t a direct fit. I expected this, and while I probably pestered RAW Brokerage, Wiring Specialties, and the various forums on the internet more than they would have liked, in the end we figured it out.



A quick list of my troubles:

  1. My OEM Oil Pressure Sensor used a different plug than the one provided. I probably don’t have the factory RB sensor. I just re-pinned the proper plug for the solution here.
  2. My ABS power plug was hidden in the wheel well and wasn’t where it should have been. It took me awhile to find this.
  3. My clutch switch (or Park/Neutral sensor)  was cut/removed and connected together so the vehicle would start after the auto to 5spd swap. I need to get a new plug for this to finish cleaning up.
  4. My S14 wiper amp is missing and I’ve been rolling with an R33 wiper amp for the past few years. I’m sourcing an S14 wiper amp just to be proper here.
  5. My fuel injectors are not OEM and I never knew that my injector subharness has been custom since day 1. The plugs didn’t match so I used my original harness here (It’s in fine shape).

Despite my few dilemmas here, the car is in surprisingly good shape having gone through 3 engines.


Here is the difference between my injector subharness plugs (Tomei plugs for Denso Injectors) and the OEM.

Wiring Specialties uses quality parts. Here is the main ECU plug.

New Harness

Old Harness

If you’re considering doing a swap and aren’t an electrical genius, do yourself a favor and buy the harness. You might also consider picking up a patch connector for the harness. It goes between the harness plug and the ECU (in my case the AEM EMS). You just find the wires you want to tap into and do it on the patch connector so you don’t damage your harness wiring in things like a boost solenoid or AFR sensor. It also lets you move your standalone a little further out of the way so it’s not right under your feet on the passenger side.


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