Does The Rx 400h Hybrid Harbours A Dangerous Design Fault

[BobBass]

Since we're discussing the 400h steering, here's what CNET had to say about the '06:

The power steering on the RX 400h sometimes feels a bit rough, an issue we've noticed on other hybrids. Conventional cars obtain constant hydraulic pressure for the power steering system by running a pump off the crankshaft pulley. Because the gas engine on the RX 400h isn't always on, its power steering runs off a 42-volt electric motor that is always operational, preventing interruptions in power assist. The downside we noticed was a decidedly notched feel to the steering at times, almost as if the initiation of assist could use a little more damping. It's not a big issue, but in a vehicle of this caliber, we notice it more than we would in, say, the Toyota Prius.

I guess I can generally agree with their observation, but it doesn't bother me in the least. Of course, if the steering operation REVERSED, that would be a real "bum steer."

CNET link

[nick49]

I haven't posted or even been here in months, but just happened across this post and had to check the steering on my wife's 400h first hand. I looked under the dash and found the steering column where it enters the firewall, then crawled underneath and found where it enters the gearbox on the rack housing. I observed movement at this point while my wife turned the steering wheel R & L. This system is purely mechanical from the steering wheel to the rack housing. Turn right and the rack moves to the left pulling the steering knuckle behind the pivot to the left and the front of the tire to the right.

What the original poster claimed with the vehicle moving opposite to the direction the steering wheel was turned is not possible with a mechanical system like the Lexus. If the steering was electrically controlled thru servos and was poorly designed it may be possible for this to happen, but certainly the engineers would have forseen this possibly and engineered it such that it couldn't happen.

[RXREY]

Yes, this story smells like a bad piece of fish, or stinky European cheese. I am a bit skeptical about this post but as I said, if there's a serious defect with our Lexus, I'd just get something else. As I said in a previous post, it's a CAR, not a person or a pet. I would not hesitate to just buy something else. I happen to think I bought the best car that I could get and it has been flawless for me. Outside of the irritating fact that I had to get new tires after one year,10,000 miles, it's been an amazing machine.... amazing. Thanks for listening, Rey

[SW03ES]

Not to downplay the situation, but you should peruse the MB forums some time...

Never one to miss an opportunity to bash MBZ, eh?

I grow more convinced by the day that you're a Lexus employee.

I don't think anyone would have doubts about that. Lexus is THE BEST, MB, BMW- BAD BAD ;)- well it' not so hard to figure out who's here ;).

Why are you surprised that on a Lexus enthusiast club forum you have members who are staunch fans of Lexus vehicles. Go on any forum, you'll find the same thing. Post in a MB forum you think Lexus is a better car. You will get REAMED.

RX400h doesn't work for Lexus. He's just a Lexus fan. If you don't want to read what Lexus fans have to say, don't post on a Lexus enthusiast site.

Thats not a request either. We're not going to tolerate anybody's opinion being devalued or our members being rideculed for being fans of this car company. You're welocme to your opinions, and you're welcome to express your opinions. However, you've got to swallow the opinions of others too.

[jkatsoudas]

Not to downplay the situation, but you should peruse the MB forums some time...

Never one to miss an opportunity to bash MBZ, eh?

I grow more convinced by the day that you're a Lexus employee.

I don't think anyone would have doubts about that. Lexus is THE BEST, MB, BMW- BAD BAD ;)- well it' not so hard to figure out who's here ;).

Why are you surprised that on a Lexus enthusiast club forum you have members who are staunch fans of Lexus vehicles. Go on any forum, you'll find the same thing. Post in a MB forum you think Lexus is a better car. You will get REAMED.

RX400h doesn't work for Lexus. He's just a Lexus fan. If you don't want to read what Lexus fans have to say, don't post on a Lexus enthusiast site.

Thats not a request either. We're not going to tolerate anybody's opinion being devalued or our members being rideculed for being fans of this car company. You're welocme to your opinions, and you're welcome to express your opinions. However, you've got to swallow the opinions of others too.

I have no problem with someone being a fan of something. However, RX400h's dig on MBZ in this thread in particular (but not unique to this thread) came completely out of left field. If you can't be a fan of something without taking pot shots at something else to support your opinion that doesn't seem like a very well-defended opinion. If you can't tolerate someone coming onto this forum and not being all starry-eyed over everything Lexus it seems to me that you're the one thats intolerant of peoples' opinions. If this is jus too inflamatory for you, please feel free to ban me.

[Jim Clark]

I haven't posted or even been here in months, but just happened across this post and had to check the steering on my wife's 400h first hand. I looked under the dash and found the steering column where it enters the firewall, then crawled underneath and found where it enters the gearbox on the rack housing. I observed movement at this point while my wife turned the steering wheel R & L. This system is purely mechanical from the steering wheel to the rack housing. Turn right and the rack moves to the left pulling the steering knuckle behind the pivot to the left and the front of the tire to the right.

What the original poster claimed with the vehicle moving opposite to the direction the steering wheel was turned is not possible with a mechanical system like the Lexus. If the steering was electrically controlled thru servos and was poorly designed it may be possible for this to happen, but certainly the engineers would have forseen this possibly and engineered it such that it couldn't happen.

Nick:

Thanks for doing that little bit of research for us. As I stated in an earlier, I seriously doubted Lexus would eliminate the mechanical link from the steering wheel to the rack, it would be too risky, the potential for total loss of steering or reversed steering could have dire consequences.

[RXREY]

I hope that I didn't sound negative in earlier posts. I am not aligned to any company. I do well but not so well where I have more than one car. So whatever I do have, I like. It's been a long time since I bought whatever I can buy with the little money that I had and in those times I did find used Toyotas were fabulous. When I wanted my first luxury vehicle I opted for Lexus after reading and asking friends about their Lexus,BMW,MB, anything that they had. It's my first Lexus and it's been great. As I said, I am not aligned or married to the thing so if anything starts to feel funky, out it goes! I would probably get another Lexus though. I've seen what other people have too deal with with other luxury brands and I feel comfortable with my Lexus dealer and my car...after two years it's been great. I know there are many great cars out there, I have one! I just felt that the original post here was a little off base. Not because he said anything negative, every car has it's issues, but it was just so off. How can a car company make a car that would turn the opposite direction? Anyway, I'm not a Lexus man, I merely own a Lexus. I am a "Life" man and have many other things that fill my life with joy. I do love my car, I aint gonna lie! Anyway, just be grateful that we can get a nice car,eh? Many people won't even eat today or sleep indoors! warmly, Rey in L.A.

[RX400h]

Not to downplay the situation, but you should peruse the MB forums some time...

Never one to miss an opportunity to bash MBZ, eh?

I grow more convinced by the day that you're a Lexus employee.

I don't think anyone would have doubts about that. Lexus is THE BEST, MB, BMW- BAD BAD ;)- well it' not so hard to figure out who's here ;).

Why are you surprised that on a Lexus enthusiast club forum you have members who are staunch fans of Lexus vehicles. Go on any forum, you'll find the same thing. Post in a MB forum you think Lexus is a better car. You will get REAMED.

RX400h doesn't work for Lexus. He's just a Lexus fan. If you don't want to read what Lexus fans have to say, don't post on a Lexus enthusiast site.

Thats not a request either. We're not going to tolerate anybody's opinion being devalued or our members being rideculed for being fans of this car company. You're welocme to your opinions, and you're welcome to express your opinions. However, you've got to swallow the opinions of others too.

I have no problem with someone being a fan of something. However, RX400h's dig on MBZ in this thread in particular (but not unique to this thread) came completely out of left field. If you can't be a fan of something without taking pot shots at something else to support your opinion that doesn't seem like a very well-defended opinion. If you can't tolerate someone coming onto this forum and not being all starry-eyed over everything Lexus it seems to me that you're the one thats intolerant of peoples' opinions. If this is jus too inflamatory for you, please feel free to ban me.

Well, let's look at a similar situation to see if you would view it as off base.

Back in the late 80s, Chrysler was having a torrid time with failing automatic transmissions. (Check any number of websites to verify this). Now let's say that an owner of an 89 Chrysler New Yorker and an Lexus LS400 posts (in a Lexus forum) that his New Yorker has been more reliable and even handles better than his Lexus. In fact, he states that he would NEVER buy another Lexus again.

What type of response do you think he (or she) wll receive? Should he get upset and battle the Lexus owners, insisting that since his Chrysler has been trouble-free, our opinon of Chrysler New Yorkers should change dramatically?

[SW03ES]

I have no problem with someone being a fan of something. However, RX400h's dig on MBZ in this thread in particular (but not unique to this thread) came completely out of left field. If you can't be a fan of something without taking pot shots at something else to support your opinion that doesn't seem like a very well-defended opinion. If you can't tolerate someone coming onto this forum and not being all starry-eyed over everything Lexus it seems to me that you're the one thats intolerant of peoples' opinions. If this is jus too inflamatory for you, please feel free to ban me.

As I told you before, I absolutely have no problem with your opinions. You put them forward in an intelligent, coherant, and respectful way.

My only issue is your repeated attempts to call RX400h out into an altercation. You do it all over the place, not just here.

If you want to disagree with RX400h or anyone else, then do that. But can saying incendiary BS like "I grow more sure that you're a Lexus employee by the day" or "If RX400h were here he'd say blah blah" in threads he's not even posting in.

If you're incapable of dealing with RX400h's opinions, simply stop reading his posts.

[jkatsoudas]

I have no problem with someone being a fan of something. However, RX400h's dig on MBZ in this thread in particular (but not unique to this thread) came completely out of left field. If you can't be a fan of something without taking pot shots at something else to support your opinion that doesn't seem like a very well-defended opinion. If you can't tolerate someone coming onto this forum and not being all starry-eyed over everything Lexus it seems to me that you're the one thats intolerant of peoples' opinions. If this is jus too inflamatory for you, please feel free to ban me.

As I told you before, I absolutely have no problem with your opinions. You put them forward in an intelligent, coherant, and respectful way.

My only issue is your repeated attempts to call RX400h out into an altercation. You do it all over the place, not just here.

If you want to disagree with RX400h or anyone else, then do that. But can saying incendiary BS like "I grow more sure that you're a Lexus employee by the day" or "If RX400h were here he'd say blah blah" in threads he's not even posting in.

If you're incapable of dealing with RX400h's opinions, simply stop reading his posts.

Just so I'm clear on the rules of the forum- it's OK to post that MBZ or BMW or (insert make here) are pieces of *&$% in every thread I post in, but if I point out that someone else does this repeatedly, that's not OK. Gotcha.

[SW03ES]

You can post any opinion you want as long as its posted in a respectful manner.

You CANNOT make personal attacks or make postings that are derisive or that are the basis for drawing another member out into a flamewar.

Your continued attempts to call RX400h out fall into the latter category.

If you can't deal with some anti-Mbz or BMW opinions on a Lexus forum maybe you shouldn't belong to one. I have never seen RX400h post his opinions in a disrespectful way or try and make personal attacks towards you or anyone else.

As for him posting things in "every thread you post in", I've seen you respond to opinions he's voiced AFTER he's voiced them as well as calling him out in threads he's not even participating in, so the whole "he posts wherever I do just to get at me!" argument won't work here.

[rgray]

Thanks SW03ES for making the effort to reduce the trash talk. If we go back to the topic of this thread, I hope most people would find it difficult to believe that a mechanical linkage, all of a sudden works in reverse. That defies logic. I think what the German engineer is really meaning to say is he had to overcome the steering wanting to assist in the opposite direction of where he wanted to turn. So now it would be interesting to see what controls the electronic power steering, and can it get a reverse signal that would force the rack in the opposite direction.

This seems highly possible if you look at this for an example

Electric Power Steering

It seems like the only way to really engineer against all failure types would be to have an over current type of cutout to make the car revert to manual steering. But that is just common sense as I have no engineering training.

[williz]

Thanks SW03ES for making the effort to reduce the trash talk. If we go back to the topic of this thread, I hope most people would find it difficult to believe that a mechanical linkage, all of a sudden works in reverse. That defies logic. I think what the German engineer is really meaning to say is he had to overcome the steering wanting to assist in the opposite direction of where he wanted to turn. So now it would be interesting to see what controls the electronic power steering, and can it get a reverse signal that would force the rack in the opposite direction.

Hi all!

Let me suggest that we all stop guessing around here. Fact is that the incident happened and it is verified by a lexus dealer. The german lexus user forum is waiting for a statement from lexus.

rgray is right, the mechanical steering was not turning in the opposite direction but the car was moving not in the direction his driver wanted.

Again let’s wait for some official response and more facts.

[RXREY]

I will go along with what you guys are saying. I just took the original post literally and it didn't sound right. I didn't know that there were issues with certain members and felt that I might have been the one that was coming off strong or dismissive or even negative. Anyway, yes, lets wait and see what happens at this point regarding the steering issue and by all means, lets all be civil and respectful of one another...darnit! Warmly... and respectfully, Rey

[pitti2]

Good Evening!

It has been stated that during my driving the steering suddenly happened to be kind of „erratic“ while driving in town, causing me to stop immidiately. Road condition: dry

If this malfunction would have happend 3 min later, a desaster at German Highway could have been the consequence. I have been on my way to the Highway.

During my 3 visits at the local Lexus Dealer Hamburg East during repair they confirmed to me as it has been stated also in a posting in the EU Lexusownerforum:

At the lifting ramp any movement at the steering wheel however slight to one direction causing the tyres to powerfully run to the opposite end stop.

As asumed in several postings the reason could have been originated in a malfunctioning of the VDIM el. steering management

Even after 4 weeks neither did I got an official report from LEXUS GERMANY HQ, nor have I been successful to negotiate in a repurchase of the car at a price I have been willing to compromise.

The LEXUS DEALER who has repaired the car did a marvellous job.

Very obviously there happened to be quite a gap comparing customer treatment here in EU with the US. Certainly equivalent to differences in customer rights in both regions....we are living miles away from US customerfriendly conditions.... eventhough the consumer price for this piece of car is EUR 60.000.--

Thats my first experience with a Lexus and as I asume, my last one also. I am going to sell this car because I lost my confidence.

[wwest]

There is no 2005 400h.

Something is up here. For one what he is saying happened should not be possible. The steering is a mechanical rack and pinion, he says its the power steering steering in the direction opposite his steering inputs. That should not be possible since the steering rack is just that, a mechanical rack. All the power steering does is help with the effort.

Makes no sense...

Sorry, I just researched this issue at techinfo.toyota.com. At the bottom of the stearing shaft, the very bottom, is the torque sensing assembly. Between the upper stearing shaft and the pinion gear is a torsion rod. There are two rotational position sensing devices, one at the top of the torsion rod portion of the stearing shaft and one at the bottom. the idea is to sense the level and direction of torque being applied to the stearing shaft and provide DC motor drive levels and polarity accordingly.

Were either of sensors to come loose and rotate ever so little, or the torque sensing rod/shaft take on a permanent "twist", the sensing signal could very easily get out of phase and that might result in reverse polarity being applied to the drive motor. It isn't likely that the DC drive motor could bias the stearing very much opposite the position of the stearing wheel but it could clearly do so to the extent of the level, amount, of twist the torsion shaft could accept before reaching it's "twist" limit.

It would certainly make it hard, VERY hard, for a driver to keep the vehicle in the center of a lane of travel. It would be like having a rubber wind-up band between the stearing wheel and the rack and pinion mechanicals, lots of hysterisis between left and right stearing. Maybe as much as a 1/4 turn of the stearing wheel and all the while with the DC motor "torqueing" the rack and pinion in the opposite direction you wish to turn.

NOT fun...??

[wwest]

Yes, this story smells like a bad piece of fish, or stinky European cheese. I am a bit skeptical about this post but as I said, if there's a serious defect with our Lexus, I'd just get something else. As I said in a previous post, it's a CAR, not a person or a pet. I would not hesitate to just buy something else. I happen to think I bought the best car that I could get and it has been flawless for me. Outside of the irritating fact that I had to get new tires after one year,10,000 miles, it's been an amazing machine.... amazing. Thanks for listening, Rey

Now go back and see how much "twist" the torsion rod within the sensing unit will take. Turn the stearing wheel as far to the right as you can without applying enough force to actually move the front wheels and now repeat the same procedure to the left. However many degrees of "slop" you have just measured is how "loose" the overall stearing coupling would be were the electronics to fail in the manner described in my previous post. Additionally, with power applied, while you're turning the stearing wheel, "correcting", to the left the DC motor drive will be oposing you.

[RX400h]

There is no 2005 400h.

Something is up here. For one what he is saying happened should not be possible. The steering is a mechanical rack and pinion, he says its the power steering steering in the direction opposite his steering inputs. That should not be possible since the steering rack is just that, a mechanical rack. All the power steering does is help with the effort.

Makes no sense...

Sorry, I just researched this issue at techinfo.toyota.com. At the bottom of the stearing shaft, the very bottom, is the torque sensing assembly. Between the upper stearing shaft and the pinion gear is a torsion rod. There are two rotational position sensing devices, one at the top of the torsion rod portion of the stearing shaft and one at the bottom. the idea is to sense the level and direction of torque being applied to the stearing shaft and provide DC motor drive levels and polarity accordingly.

Were either of sensors to come loose and rotate ever so little, or the torque sensing rod/shaft take on a permanent "twist", the sensing signal could very easily get out of phase and that might result in reverse polarity being applied to the drive motor. It isn't likely that the DC drive motor could bias the stearing very much opposite the position of the stearing wheel but it could clearly do so to the extent of the level, amount, of twist the torsion shaft could accept before reaching it's "twist" limit.

It would certainly make it hard, VERY hard, for a driver to keep the vehicle in the center of a lane of travel. It would be like having a rubber wind-up band between the stearing wheel and the rack and pinion mechanicals, lots of hysterisis between left and right stearing. Maybe as much as a 1/4 turn of the stearing wheel and all the while with the DC motor "torqueing" the rack and pinion in the opposite direction you wish to turn.

NOT fun...??

Boy, I would hate to be a mechanic who tries to pull the wool over Double - U's eyes! "Technical Analyst" is a good nickname for W!

[williz]

remember our discussions about the first thred here!?

if your car was manufactured between 04/03/2005 and 06/10/2006 expect a recall to replace the power steering of your car.

here is the customer satisfaction campaign for europe power steering replacement

[riwyle]

wwest- Been missing you. Good to read your often thought provoking, usually insightful, frequently passioned comments/analysis again.

[RX400h]

I noticed that the statement includes "if necessary". That may indicate that only certain conditions will merit the replacement of the steering rack. Of the many tens of thousands of RX400hs on the road here in the US, I haven't heard of more than one that has had power steering issues, and I've been on this forum for more than 4 years now.

remember our discussions about the first thred here!?

if your car was manufactured between 04/03/2005 and 06/10/2006 expect a recall to replace the power steering of your car.

here is the customer satisfaction campaign for europe power steering replacement

[williz]

I noticed that the statement includes "if necessary". That may indicate that only certain conditions will merit the replacement of the steering rack. Of the many tens of thousands of RX400hs on the road here in the US, I haven't heard of more than one that has had power steering issues, and I've been on this forum for more than 4 years now.

remember our discussions about the first thred here!?

if your car was manufactured between 04/03/2005 and 06/10/2006 expect a recall to replace the power steering of your car.

here is the customer satisfaction campaign for europe power steering replacement

in europe we had three, china had some. the recalls started in china and please note that this problem is affecting IS and GS as well, but see yourself here Toyota to highway administration

[s10]

I noticed that the statement includes "if necessary". That may indicate that only certain conditions will merit the replacement of the steering rack. Of the many tens of thousands of RX400hs on the road here in the US, I haven't heard of more than one that has had power steering issues, and I've been on this forum for more than 4 years now.

remember our discussions about the first thred here!?

if your car was manufactured between 04/03/2005 and 06/10/2006 expect a recall to replace the power steering of your car.

here is the customer satisfaction campaign for europe power steering replacement

in europe we had three, china had some. the recalls started in china and please note that this problem is affecting IS and GS as well, but see yourself here Toyota to highway administration

So, from what I read the potential defect could lead to some loss of power assistance when turning, not inverting.

But it was fun to read this thread again...