New GX 550 wiring harness and modules compatibility for electronic options - MTS, crawl, Rear locker?

[GXXR]

I didn’t see a thread on this yet, and if I missed it, I apologize.

The topic I would like to investigate is if the wiring harness, including the auxiliary harness being pre-wired is the same for all GX 550 models bound for the USA market. If it is the same harness, I want to confirm if Toyota/Lexus uses modules for this new model to control special features, or if it is done through a body control module/main computer.

I am trying to figure out if like the previous generation of GX 460, you can add MTS, Crawl control, adding factory auxiliary switches, and possibly a rear diff locker to a new GX 550, If the wiring harness has the place to plug in the modules, and the modules are available to purchase.

I am looking at buying a premium base model and possibly adding a few of these features to customize some things “ala carte” to get more of the Overtrail capabilities, without the limitation of being without a 3rd row seat.

 

[Garauld]

This begs another question - has anyone seen/bought a factory repair manual as well as factory wiring diagrams? The diagrams would be useful for ala carte mods.

 

[Wayne]

I would be interested if anyone has found a part number for the pigtails that plug into the 3 plugs that are controlled by the switches they added to the 2025 OT. I have found the connectors, one under the dash near the switches and one on either side under the hood and under the plastic trim panel that is over the front of the engine compartment. These two are hard to access. Their general location is shown on page 453 of the user manual.

 

[Garauld]

Wayne - got some photos of them?

 

[Wayne]

Here are a couple, one blurry.

 

[Garauld]

You have both sides of the connector there already and can be separated. I believe the colored dots are just filler plugs that could be removed and then wires run from your new device with the appropriate mating pin or socket would be inserted. The different size plugs denote different wire gauges and pin/socket sizes. I would think Lexus, being a Toyota subsidiary, would use similar wiring connectors. The Lexus wiring diagram guide should list the connector p/n's although a sharp Lexus parts dude should be able to get that also. Maybe it's online too.

 

[Garauld]

I suggest that once you disassemble that connector take it to a shop that installs stereos or car alarms and see if they can attach some pigtails to it