New GX 550 wiring harness and modules compatibility for electronic options - MTS, crawl, Rear locker? (1 Viewer)

[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

 

[Wayne]

I separated the connector and this is what the removable part looks like. I took out a couple of the rubber plugs. The connector shell would need some female contacts to mate with the two different sizes of blades in the connector that is wired to the car. This part has no metallic components, it is just plastic. I tried Googling these photos and found lots of connectors that looked slightly like this, but not the real connector. I will try the Lexus dealer. I couldn't find anything on the parts diagrams online which seem to just be for 2024 GX550s which don't have the AUX switches.

 

[Garauld]

Does the white piece come out? A photo showing the pins on the switched connector would be useful.

 

[Wayne]

Sorry I didn't take any photos of the male end. What I did to power my radio was to use two 0.25" female disconnects to mate to the two larges blades on the connector. That is a 15A circuit, which is enough to power my Icom IC2730B amateur radio.

 

[jmercer46]

I found a seller on EBay that has been very receptive and I have sent him pics from this thread and the owner’s manual. He builds the pigtails for the Tacomas and has built a pigtail to try on the GX550 Overtrail. He is looking for someone to try them out. I purchased one, but I have my name on the allocation list and probably will not have my Overtrail for several months. I feel like they will be perfect. He is in NC and I will share a screen shot of the listing and his contact information. If you order, he said to put a note on the order that says you are trying out on a GX550 and he will make the changes and include instructions.

 

[jmercer46]

Here is the listing

 

[jmercer46]

Here s the link: Auxiliary Switch Connector/Wire Harness for 2024 Toyota Tacoma AUX Plug Adapter | eBay

Here is the company:
Shade Sound and Security
5101-H Unicon Drive
Wake Forest, NC 27587
1-844-SHADE-55 (1-844-742-3355)

If anyone is able to try on their 2025+ Overtrail and let the group know, that would be awesome!

 

[chris.gio]

What have folks used the switches for so far?

 

[Rosco]

I was wondering if there has been any progress on this? Considering buying a Premium Plus and interested in the possibility of adding MTS and Crawl Control.

 

[jps8460]

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.

It’s all available on Tech Info. You can buy a 3day, week, and annual subscription I reckon.

TIS

 

[roaniecowpony]

I would approach this from the other direction. Buy the more complex system options you want. Buy the OT, then put in a 3rd row seat. That has to be easier than all the module and wiring BS. In the end, probably cheaper too not to mention the hundreds of hours dedicated to this kind of project. Then when you end up with a late model frankenstein that nobody wants, you're really just wasted time and money. I've seen a lot people buy less than they want and modify it one part at a time. I'm a jeeper and I have friends that do this. I used to be a forum moderator for GM trucks and watched this over and over.

 

[48Njim]

Any tech savvy Linux coders. github users or capable script writers out there?

My plan for this long dark winter is to attempt a DYI download of the complete OEM repair /service manuals - but I'm old and slow.

The solution seems to be buying a short term Toyota Tech Stream subscription and using some scripts to download the entire service/repair and electrical manuals (estimate 40Gb?).

Then make an functioning iso. And of course, share via torrent to the rest of us GX550 owners. Sorry I don't fully understand all this stuff. But I'm in if you understand and can help.

DM me for a github link, or how it was done for Land Cruiser service/repair manuals.

Remember: we own these vehicles, and we need (have the right) to maintain, repair (and modify) them.
Cheers!

 

[roaniecowpony]

Sharing the entire manual online would expose you and the site owners to copywrite and proprietary data infringement big time. It's that little thing you acknowledge before you can use these types of data. A few pages here and there is much less likely to get the attention of them. But, when you post the whole document, you cut into their revenue stream or cut it off. That gets their attention. Imagine if you posted the latest Stephen King book online in its entirety.