peasodos

iTrader: (1)

Try disabling the Pre Collision System, button is under dash, driver side, near TPMS Reset button.

Osmann

These are the only two buttons I have there, I have read that the AFS has to do with the way my headlights work, that’s it. So unfortunately I don’t think that’s the fix, I was exited for a moment there. I love the car but the driving “drives” me nuts….

Saadq12

did you check your sway link stabilizer and other suspension components thoroughly?

is there anyway someone can record a video of this steering issue problem. Strap a couple phones or go pros or something around the vehicle.

I know it will be hard to tell exactly but would love to see the delayed input since there’s been so many complaints. I haven’t experienced anything similar in the 70k miles I’ve put on since owning the car so makes me wonder if this is just particular to the GS’s with rear steering. Would also love to know the milage of everyone experiencing the issue.

elbow

I've been experiencing the same issue with my 14 RWD Luxury Package and I replaced the LCA's with the GSF ones. Definitely made an improvement to the reactiveness of the steering as well as improving on the overall feel of the front end. But it did not eliminate this issue. Replacing the struts and shocks next but still undecided on the route I'm taking as far as those are concerned.

I recently had my wife sit in the drivers seat and turn the steering wheel with the car on but engine not running. Looked to me like the steering rack had some play in it but there don't appear to be any replaceable parts like steering bushings. On previous models, these were a wear item that produced similar symptoms when worn. But, with this model, it requires an entire rack replacement. Thinking that may be my next recourse if replacing the dampeners doesn't solve things.

Di66er

In my 2013 GS450h I started experiencing the same problems described here. This Tuesday, the car’s steering was so unstable it wasn’t drivable. I jacked up each corner of the car and attempted to wiggle the wheel up and down then side to side. The passenger from had significant play side to side. To fix I replaced the lower ball joint, upper arm, and shocks (my car has 145k miles on it and if I’m taking the knuckle off, I’m replacing shocks and upper arm as well).

This fixed my problem. No sloppy steering and no shimmy above 60mph. I hope this helps some of you.

elbow

Still dealing with exact issue and it is rendering an otherwise perfect vehicle, nearly undriveable on the highways...where it should shine the brightest. I found an article on here where someone corrected this issue with a new steering rack ($1300 in parts alone) and this will likely be in my future as I cant see anything else causing this. Multiple tires, (Michelin, Pirelli, Continental) multiple wheel setups (staggered, squared, 18", 20"), multiple alignments, new suspension components and nothing has put a noticeable dent in this issue. Some days the car tracks straight, others it's like a confused old man not sure if it wants soup or salad and this happens on the same roads so it isn't road conditions, not that the road should ever influence a car at this level this much. I have other vehicles (MDX, Silverado, Civic Si, Tundra, Pilot) that I travel this road with and have never felt this before. My last Lexus had some steering issues but nowhere near this bad. My wife loves the car but refuses to drive it on the highway because of this unpredictability. 220k miles and I can let go of the wheel on my 16 year old Pilot and never worry about where it will stray. If I glance at the GS' heated seat control, I could look up and be in another lane. That is just unacceptable. I'll continue to investigate and diagnose because I love so many things about this car and there must be a fix somewhere. But if the steering rack doesn't fix it, I'm pretty much lost after that.

7eight

I've been dealing with this close to a year since getting the car, new tyres and alignments have not done anything. Will try the vgrs reset at dealer and see what they say.

Seems my steering defaults slightly left on the steering wheel no matter if it's kept perfectly centred during an alignment, so am hoping maybe it's some software or sensor glitch that they could fix with a reset.


But not sure if anybody has been able to resolve it 100% without replacing the steering rack?

Mangsailor

I'm going to look at how the power steering assist motor is coupled to the column later today. Maybe there's a bad lovejoy in there or its something else.

My wife's Elantra had a clunk in the steering I hunted for years, could never find it until I stumbled on that there was a rubber coupling snubber between the motor and column. So then I googled Elantra rubber coupling and there were several videos on it, and even a guy sources new ones that were made out of a different material.

I thought though the column motor had position feedback on it. Maybe it's just how the PID is tuned.

petr4271

Who did your alignment ? Lexus ? Its important its done within proper specs of front toe inwards of 0.2 degrees or 4mm. If your toe is out, car will be all over the place. If you drive straight and move steering any direction and let go off steering wheel it should correct itself to wery straight, if not your alignment is off, nothing to do with VGRS. No matter what, if your car pulls to side or wont correct itself stright from turning its 100% alignment, tire pressure, bushings within suspension, road bank, road imperfections.

Reason why it seems better when in sport+ mode is because it sets rack in tighter mode, but thats all.
Also reason why some people claim only replacing whole rack solved the problem is because if inner tier rods go bad you cant replace only those as lexus dont make them, you have to replace whole rack, same with rack bushings. The way lexus designed it. There is aftermarket option for bushing but not inner tie rods.
Someone also sugests lower control arms and ball joints are loosed. Yes they will definitely contribute to steering wobblesness as suspension and steering in GS is super tight and even tiny looseness will cause problems. Its chain reaction. The play within suspension or steering will be detected by many sensors of VGRS and it will react acordingly ****ty.

7eight

So you think an alignment at a lexus dealer and not tyre shops could solve the issues? They didn't notice any issues at my last servuce besides inner tyre wear on the rear, so I assumed that should fix it.

not sure if it would be worth going to a Toyota dealer 5 mins away from me first before driving or booking in my car an hour away at the lexus dealer. (I'm not in usa and my car is RHD so this issue seems to be a global 1)

any idea if there are seperate alignment specs for F Sport cars compared to the non F sports (I've looked and I can't seem to find anything) or whether alignment should be done in sport+ mode?

Honestly most of the tyre shops around here have probably never seen 1 of these cars and I'm not sure if specs for a 2015 gs350 would differ from 2014 F Sport? (1 shop had to update their systems to even show lexus vehicles)

petr4271

Ad 1: yes absolutely

"any idea if there are seperate alignment specs for F Sport cars compared to the non F sports". YES, f sport is RW STEERING with staggered wheels. This has different alignment set up than AWD non f sport.

regular tire shops know basic stuff how to do alignment, not special ones like f - sport. You can do even better job yourself at home by using string and measure manualy your front toe, that will at least give you an idea what your situation looks like. Plenty of videos on youtube , search for DIY alignment.

As per your rear tire wear, that indicates camber issue and worn upper control arm link bushings, this also contributes to steering performance.

7eight

Thank you, I don't think mine has the rear wheel steering just a F-SPORT RWD (not 100% sure though) and on my alignment printouts I always got gs350 4x2. Which I assume means RWD over here.

is there a printout of an F Sport alignment specs somewhere so I could compare with what I have?

also would this explain why my steering wheel seems to default to an almost imperceptible slightly left position?
​​​​​
You're starting to give me hope that it's fixable! . Maybe during the servuce they didn't inspect the suspension/steering components as good as they should have to report no issues.

Mangsailor

OK, screw all that. The motor is built into the housing of the horizontal assembly of the rack. It's recirculating ball, and the shaft inside is threaded and is thus shifted left/right as you steer the car.

It receives it's input based off of torsion sensed by two sensors in the "vertical" part of the rack.

From the manual:

(5) If the vehicle is driven straight and the driver does not turn the steering wheel, the specified voltage that is output at this time is determined by the power steering ECU assembly to indicate the neutral position of the steering wheel. Therefore, the power steering ECU assembly does not apply power current to the motor.

(6) When the driver turns the steering wheel, a relative angle difference is created between the rotor portions of the resolver sensor 1 and resolver sensor 2, only in the amount that is equivalent to the twisting of the torsion bar.

(7) The stator portions of the resolver sensor 1 and resolver sensor 2 receive the angles of the rotors in the form of electric signals and output them to the power steering ECU assembly. Based on these input signals, the power steering ECU assembly calculates the relative angle difference between the angles detected by the 2 resolver sensors.

(8) The power steering ECU assembly calculates the torque value based on that difference. Then, the power steering ECU assembly calculates the assist power current based on the calculated torque valueand vehicle speed. Based on the information obtained from the rotation angle sensor, the power steering ECU assembly actuates the motor at a predetermined current.

See attached

richard203

iTrader: (1)

i wonder if we can replace the power steering ecu to another power steering ecu to make the steering wheel more stiffer.

bclexus

@Mangsailor - Look at THIS It may be of interest to you an maybe others...