GX460 & GXOR B.S. thread

[Splat]

Here's what ChatGPT says:

Based on the pattern you described, this sounds much more like an intermittent electrical or wheel speed sensor issue than a mechanical brake problem.

The key clues are:
No warnings until you hit the brakes over a rough patch.
Warnings change with bumps and vibration.
Most warnings clear after sitting still for ~30 seconds.
ABS and TRAC remain illuminated.
The warnings flicker on/off rather than staying consistently on.

On the GX460, the ABS/VSC/Traction Control systems are the foundation for many other safety systems. If the ABS module loses a wheel speed signal or has an intermittent electrical fault, it can temporarily disable:

ABS
Traction Control (TRAC)
Vehicle Stability Control (VSC)
Crawl Control/Multi-Terrain Select (if equipped)
Sometimes even PCS, LDA, or 4WD-related warnings depending on model year.

Most likely causes (in order)

1. Loose or damaged wheel speed sensor or wiring (most likely)
A bump or braking can flex the suspension enough to momentarily open a broken wire.

Common locations:
Front wheel speed sensor harness where it bends near the steering knuckle.
Rear axle sensor wiring.
Connector that's partially unplugged.

This is probably the first thing I'd inspect.

2. Failing wheel speed sensor
An internal crack in the sensor can cause intermittent operation that shows up when the suspension moves.
The ABS computer sees one wheel suddenly disappear and throws multiple warnings.

3. Loose ground or battery connection
Since every warning briefly appeared, it's also worth checking:
Battery terminals
Main chassis grounds
Engine ground strap

A voltage interruption can light up almost every warning lamp.

However, if the battery or charging system were the problem, I'd expect additional symptoms like:
Radio rebooting
Clock resetting
Dim lights
Slow cranking

If none of those happened, I'd lean toward an ABS-related issue.

4. ABS actuator/module connector
Less common, but a loose connector at the ABS hydraulic unit could react to bumps.

5. Damaged tone ring/encoder
If the magnetic encoder in the wheel bearing or tone ring is damaged, bumps can make the sensor signal drop out.

What I'd do next - Read the ABS codes. This is the most important step.

A generic OBD-II scanner usually won't read ABS codes.
Use:
Techstream
Autel
Launch
Topdon
Any scanner capable of Toyota/Lexus ABS diagnostics

The stored code will often identify the affected wheel, such as:
Left Front Speed Sensor
Right Rear Speed Sensor
Wheel Speed Signal Missing
Inspect visually

Look at all four wheel speed sensor wires.

You're looking for:
rubbed-through insulation
stretched wiring
broken clips
corrosion
loose connectors

Because the problem changes with bumps, I'd physically wiggle the harnesses while looking for obvious damage.

Check battery voltage
Measure:
Engine off: around 12.6 V
Engine running: 13.8–14.7 V
Low voltage can cause strange electronic behavior.

The fact that the warnings disappear matters

If this were:
bad brake pads
bad rotors
bad wheel bearing (unless very severe)

the warnings generally wouldn't come and go exactly with bumps. An intermittent electrical connection is a much better fit.

My best guess - I'd estimate the odds roughly as:
60% intermittent wheel speed sensor wiring
20% failing wheel speed sensor
10% loose battery/ground connection
10% ABS module or connector issue

 

[Rednexus]

Here's what ChatGPT says:

There has been a lot of AI-generated content posted on these threads lately. When I ask it questions related to my specific field of (non-Toyota) professional expertise, it often gives a great-sounding answer that has multiple factual errors in it. Since I'm a subject matter expert in my esoteric and highly technical field, I can quickly spot the errors and know that it's BS. If you are using AI for something where you are not a SME (like troubleshooting the electrical system in a complex vehicle), you'll have no way of knowing where it's giving you BS or not, or which of the steps are BS. It seems to me (at least anecdotally) that the more technical a question, the more BS in the AI output. That's personally while I avoid relying it for areas where I'm not a SME - I'm in no position to know if it's right or wrong.

For this particularly query, I certainly agree with AI's assessment that this could very well be a loose electrical connection in the rig (I had that same thought somewhere earlier in this thread, maybe it drew from my own post). But, some of the other things it mentions - loose speed sensor wire/tone rings etc. - may cause some of the symptoms (TRAC/ABS lights) but would definitely not cause the KDSS or trans temperature lights. Those are actually separate computer modules the GX uses, rather than a single unit. AI seems to miss that point, probably because @Roody's symptoms are frankly very unique (multiple errors across multiple unrelated systems) and there are probably few cases of them out there on the internet. AI is, after all, nothing more than an probabilistic text generation machine that reads the entire internet and generates text based on how often various words/phrases go together. With Roody's probably being a bit of an outlier, it starts going in some strange directions instead of realizing that there is not a clear answer to the problem (i.e, "I can't find any instances of this specific problem").

 

[Hiluxforever]

There has been a lot of AI-generated content posted on these threads lately. When I ask it questions related to my specific field of (non-Toyota) professional expertise, it often gives a great-sounding answer that has multiple factual errors in it. Since I'm a subject matter expert in my esoteric and highly technical field, I can quickly spot the errors and know that it's BS. If you are using to to do something where you are not a SME (like troubleshooting the electrical system in a complex vehicle), you'll have no way of knowing where it's giving you BS or not, or which of the steps are BS. It seems to me (at least anecdotally) that the more technical a question, the more BS in the AI output. That's personally while I avoid relying it for areas where I'm not a SME - I'm in no position to know if it's right or wrong.

For this particularly query, I certainly agree with AI's assessment that this could very well be a loose electrical connection in the rig (I had that same thought somewhere earlier in this thread, maybe it drew from my own post). But, some of the other things it mentions - loose speed sensor wire/tone rings etc. - may cause some of the symptoms (TRAC/ABS lights) but would definitely not cause the KDSS or trans temperature lights. Those are actually separate computer modules the GX uses, rather than a single unit. AI seems to miss that point, probably because @Roody's symptoms are frankly very unique (multiple errors across multiple unrelated systems) and there are probably few cases of them out there on the internet. AI is, after all, nothing more than an probabilistic text generation machine that reads the entire internet and generates text based on how often various words/phrases go together. With Roody's probably being a bit of an outlier, it starts going in some strange directions instead of realizing that there is not a clear answer to the problem (i.e, "I can't find any instances of this specific problem").

Yep. I completely agree with that.

AI is best for Senior Engineers.

 

[Rednexus]

Yep. I completely agree with that.

AI is best for Senior Engineers.

It can be downright dangerous if it's used by the wrong hands in my field (engineering design of critical structures). I'm waiting for the first AI-caused engineering failure to occur; figuring out liability/responsibility between the engineer, their employer, and the AI company will certainly be interesting. However, I have found it's awesome and generating funny illustrations for PowerPoint presentations, and awesome for shortening the excessively-long text I tend to write into something more palatable.

In all serious I'm the most worried about younger folks in my field. I could delegate most staff engineer work to AI agents and save quite a bit of money. But, when I retire in a decade or two, there would be no one to replace me who has enough experience to know if AI is right or wrong. So I'm training all of my staff engineers on "old school" techniques and developing their engineering judgement, but certainly encouraging them to use AI to make mundane/non-valuable tasks more efficient.