https://www.clublexus.com/forums/rc-...50-fsport.html
Same issue but with the RC family

 

good news, after i've adjusted higher position, the issue seems goes away during highway drive, will test further and feedback again

 

Sounds like something you have a mechanic properly diagnose.

 

We've tried. It's pretty difficult to diagnose. It's something you have to drive with for a pretty long distance before it becomes noticeable, unless you know exactly what to look for. I took mine to the dealer and rode along with the technician, and he didn't feel anything. I even told him "Do a lane change here" or, "take this corner at 45 MPH"... stuff I knew would do it. But he claimed to be unable to feel anything.

The good news is it seems like some owners don't experience the problem to the same degree as others. In my case, for instance, ever since I adjusted my steering wheel, I haven't noticed it as much - maybe once or twice since then. Even then, I think the level of resistance was higher before I adjusted the steering wheel.

 

yeah....except the chance of you getting "Lexus tech tried to replicate it, but could not" outcome is very low... like 99% "low"
In other cases Lexus service center said the rack needs to be replaced. I am not a mechanical engineer, but when a device exhibits "failure" only at a certain time, at a certain speed, only when the steering wheel is not "wiggled" for a while, it gets "pinched" is not an indication of a faulty mechanical steering rack part, because it cant "know" when to break without any of those "inputs" somehow being provided to it. Some of it can be mechanical, sure, but not all of those are mechanical in nature consistent with what I have been seeing. To me it is a coding error or glitch in how the steering computer accepts input from, or how it handles certain conditions like "above certain speed" and "steering angle less than ... ".

What is a bit upsetting is that there is a ton of people here experiencing it, yet officially the problem does not exist and it is just mechanical and rare.

 

What was the adjustment?

Also, is there a way to somehow "unify" all the steering problem threads? Clearly it is either the same rack or the same computer module doing it.

 

Actually, as I read your initial post again, it sounds like lane keep assist is active. Turn it off in the settings and I bet your issue resolved.

 

1) my 2015 is350 does not have that option, no button to press to activate it on the panel, and an official lexus PDF doc does not state that the feature even installed on my car.

2) I agree in principle. That lane-keep feature would need some sort of lane position tracking method, generating an error from the ideal position, which would be used to "steer" the vehicle toward the smallest error by the ESM. In the absence of such error, but with the "auto-steering" still activated, the vehicle will have the resistance to any steering input. At least it is plausible.

 

I have experienced the issue only when the lane keep assist is already turned off. My former 2016 IS did not have lane keep assist either.

 

My 2014 IS 350 AWD doesn’t have that feature, but I do have the glitch after long straight drives. Someone that only drives the twisties would never see/feel it in my car.

 

yep, same for my 2015 is350 rwd. If you wiggle the steering wheel a bit when you begin experiencing it on the highway, you can sort of "reset" the "binding" for a bit... then it returns. This is why I say it is likely programmed (inadvertently) and ESM logic related and not just a mechanical defect. it is too "smart" for a mechanical defect.

 

Here is an idea - how about disconnecting the electric steering assist and trying to do the same highway run to see if it is gonna manifest. If it is ESM related, it wont manifest itself. If it is mechanical in nature, it will likely manifest at those exact speeds under the same conditions. ...

 

Well, guess what - I pulled the fuse out for EPS module (5A) and tested if the glitch is still there. The binding was still there even without the e-power steering assisting.
Also a fair warning - if you want to test it yourself - unassisted steering is VERY heavy especially at low speeds. make sure you do it safely. But if you do do it - this is how it will feel when your engine gets killed/dies while you drive, so you will get trained for this emergency situation. 😅

 

Thanks for taking the trouble to do that.

I guess this confirms it's not just some software glitch then. The question still remains as to what exactly it is.

 

Kudos for taking that on- my mom had a Hyundai Equus? The power steering went out while I was in the car, damn near threw out my back helping steer from the passenger seat. We got rid of that one quickly after that. Now she's in a GX.
This is the most annoying thing about this car for me- hopefully, someone figures it out soon. If my service contract covers it, I'll try to get the local dealership to take a look.