ECU Pinout and Wiring Harness Help(s)

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Mar 3, 2021
Hey All!

Here I am dinking around with ecu wiring due to o2 sensor shenanigans after a long-tube header install.. I can't find ox1b or ox2b at the ecu and the pinout instructions(second plug, 21 and 29) that I do have are not correct. Those were related to knock sensor territory. 🤔🧐🤯


Searched the forum to no avail, so here is a thread for anyone looking for ECU connector pinouts, wiring harness color codes, and all that kind of fun stuff.

That out of the way, can anyone tell me where ox1b and ox2b are connected at the ecu on an 06 GX470?
This is 2005 electrical wiring diagram.
Should be fairly similar for O2 sensor


  • 2005 GX 470 Electrical Wiring Diagram (UZJ120 Series).pdf
    6 MB · Views: 60
This is 2005 electrical wiring diagram.
Should be fairly similar for O2 sensor
Ooh.. This is a gem! Looks like ox1b is on plug A #18(black) and ox2b is on plug B #33(white). This also verifies the knock sensor related wires I found on the GX, including color and fault codes that popped up after following instructions from urd for their RB-U.

Unlike the 4runner diagrams everyone(including urd) is working with, it also only shows 5 plugs on the ecu vs the 6 plug design of the 03 4runners.

Looks like I'm going back in for some brain surgery!! 🤩 I'll keep everyone updated how goes it.

Thanks, back on track again thanks to @Jstawgn. Keep up the good work!!

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Alrighty! Test drove the rig, no codes.. Worked perfectly.

Thank you all!
Update on the cat delete and the Doug Thorley Long tube Headers..

Everything still works like a charm. The headers arent loud with the stock Lexus y-pipe, muffler, and resonators; Barely noticeable sound wise. Sounds a tiny bit throaty, just barely. Kind of like the stock growl intensity..

I'm seeing better mileage too(~20mi more per tank), she runs like a charm, and has noticeably more power from 2200rpm up. Especially when passing on 2 way highways. Noticebly less transmission kick downs as well when you hit those steep hills on pavement at cruising speed, but that needle climbs pretty quickly if you do decide to goose it.

Now I want to play around with the o2 sensor settings(filter/gain) and see if I can trim up the fuel mapping a little... There arent any cats to keep hot so maybe pinch out a few more mpg? Find most efficient setting perhaps. Anyone ever try this with good and feasable results?

Just wondering if I can save me some time and heartache.. Not all ideas are good ones over here, just ask my neighbor with the torched beard and brows. 🤣

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