jgamze

Does anyone know yet if they fixed/revised the tire pressure readout system to specifically tell you which tire is low in pressure so that you don't have to guess which tire actually needs more air. On my wife's Honda Odyssey, the readout specifically tells you which tire needs air, so there is no guessing. It's a really nice feature. Thanks!

boxcarfan

there is no fix or revise for anything on TPMS for Lexus

jmcraney

I have given this a lot of thought and I have come to the conclusion that Lexus has taken the correct approach to displaying the tire pressures.

The Lexus tire pressures are displayed is a a 5 position display. If it is important to you to know exactly which pressure corresponds with which tire location, you can establish a convention to tell you exactly where each tire is displayed. For instance, you can let your convention be LF, RF, LR, RR, SP (top to bottom). Each wheel has a pressure sensor, it is part of the valve stem, and each sensor has a unique ID. You have to have a technician enter the sensor IDs into the TPMS in your car - the Lexus LS460s require a special piece of electronic equipment to enter the sensor IDs via the OBDII/CANbus - in a manner to support your convention. But, once you rotate the tires the display convention no longer applies unless you reenter the sensor IDs to the correct locations in the TPMS in your car.

Having the display labeled with the tire locations has the illusion of telling you what the pressure is for a tire location on your car but in reality it is just telling you what the pressure is from a tire ID and the tire with that ID may be in a different location from what the display indicates if the TPMS was not programed after the tires were repositioned due to rotation or replacement.

Is it really important to know exactly where the readings are coming from? After careful thought, I think not. If I had a low reading on my display I don't think I should base my response on which tire was leaking. If you base your response on where the display shows the problem is and you just checked that tire, and the tires were not displayed correctly, and it checked okay, and you proceeded with a low tire under the assumption that the sensor is defective, that might be a setup for disaster. So maybe it is better to not have that illusion that you know absolutely where the problem is.

Of course if it is important to you to know exactly which pressure is from which tire location then your Lexus can do that for you too. The maintenance effort required for absolute certainty is just about the same for either type display but the unlabeled display does not have the potential ambiguity for the unsophisticated that might mislead them to check the wrong tire.

jmcraney

If knowing which display item is associated with which tire is important to you then there is another way to deal with this without any specialized equipment other than an air source and tire pressure gauge. Either increase or decrease the pressure in one tire at a time, up or down 3 PSI should work fine, and create a display map by noting which item in the display is affected. You will have to do four tires to be sure where each is displayed, then you can assume that the last one is the spare. You will have to redo this after rotation.

Mike_TX

But, Jim ... isn't that a kind of stupid and unnecessary job, given that MOST other TPMS systems tell you which tire is which? I mean, here we have one of the most luxurious cars on the market (excepting the exotics, of course), and the damn thing won't even tell you which tire is low. If you get a warning - or see that one is low - you have to grovel around on your hands and knees at all four corners of the car to figure out which one it is.

I have had a number of cars with TPMS that identified each tire individually, and each of them reset themselves if rotated ... that is, your postulation above about getting false information isn't correct. If any one of those cars' systems told the left front tire was 2 lbs lower than the others, it would always be the left front tire, regardless if the tires had been rotated a dozen times. They use unique identifiers that synch up to the position they are on the car.

I personally think it's cheap and cheesy to do it the way Lexus chose to. Even my relatively inexpensive '06 Acura TL told me which tire had which pressure, and it's embarrassing that my $75,000 LS460 makes me guess.

I might add I'm **** about tire pressure, and I keep that display up at all times. It makes me crazy to see one tire that's a pound or two different from the others and have to spend a half-hour of experimentation to figure out which one it is.

I compare this to Lexus' woefully sub-standard voice recognition system ... the king of cars has chosen to cheap out on some key systems to the extent that cars costing half as much do these things twice as well as Lexus.

Lexus should be ashamed.

jmcraney

Mike,
I am going to have to yield to you on this because you seem to know a lot more about this than I do and you obviously have a lot of experience with TPMS.

My understanding is that there are two main technologies being employed by the car manufacturers to satisfy the NHTSA mandate: Direct measuring TPMS and indirect measuring TPMS. Toyota and many others are using the direct measuring scheme in most new cars although they have used the indirect scheme until about 2006 or 07. Each technology has some unique advantages and disadvantages. One of the advantages of the indirect measurement system is that it does not require resynchronization after the tires are repositioned. The indirect measurement works by measuring tire rotation, usually through the ABS and detecting low tires through differential rotation counting scheme. As far as I know most direct measuring systems are not capable of knowing if the display is synchronized with the tire positions and that has to be determined by the user or his agent. Any way thanks for keeping me humble. It looks like I may be wrong, again.

Jeff

Mike_TX

LOL. You're probably right, but I just know I enjoyed systems like the one in my Infiniti M45:



and my (3) Acuras:



... far more than the one in my LS460 (and my IS350, as well), which give you less information.

The only thing I CAN say about the Lexus system is that it is better than the one on my friend's '08 Mercedes, which merely displays a red warning light in the instrument cluster if a tire is low. THEN you go looking for it.

LS600guy

Can the TPMS system be retrofitted, anyone know?

--------------------------
2007 LS600hL, 5 seat
2000 Lexus LX470 (traded and missed)

Mercedes SL500 AMG (garage queen)
Mercedes SLK 230 (wife's toy)
Suzuki Grand Vitara (rain & runaround)

jgamze

Its unfortunate that a luxury car manufacturer such as Lexus that symbolizes "the relentless pursuit of perfection" can not simplify and make it both easier and more useful and user friendly and helpful the tire pressure monitoring system such as Infiniti or even Honda. The way it is right now, the system is very user unfriendly and unhelpful. Its a shame that despite this, and the negative feedback that I am certain Lexus has received about the TPMS that they have not modified the system for the better.

jmcraney

Do you think it would be better to have no TPMS as opposed to what we have now? Do you think what we have now provides no useful information?

Johnny

So, you're slamming the car because of TPMS? There's a lot more to this car than tire pressure monitoring. Lexus's system may "arguably" not be the best, so that makes it subjective. I am very happy with it. When a warning comes up, as it did on my previous LS, I get out and check all the pressures. This gives me an opportunity to verify all the tires - as I would any other TPMS system. All rim/tire configurations are known to leak in immeasurable ways. After all, we're dealing with materials and conditions that are dynamically loaded, so the MTBF can be relatively short.

Lexus is not the only company to suffer this fate - tires and wheels, and monitoring systems are prone to fail, no matter what car they are mounted on. I'm sure there are compelling reasons why Lexus went this route, after trying the other, but your complaint should be directed to them instead, as you're unlikely to gain satisfaction on this board.

jgamze

The sad part is that I did complain to them through the 1-800- 25LEXUS telephone number. I talked to a live person who took my complaint. I was told that someone would follow-up with me regarding my feedback. No one ever called me back. This feedback was given to them by me several months ago.

jgamze

Also, why would I want to check all the tire pressures when it is only one tire that is low in pressure? When I get a low tire pressure on my wife's Honda Odyssey, I go right to the tire with the low pressure, and in a quarter of the time, and without any guess work on my part, the tire is filled back up and I am back in the car driving again in minimal time. It just seems like common sense. I don't get what the advantage is of the Lexus system over the system in my wife's Honda.

Johnny

I understand and sympathize with your situation. However, your posture seemed to imply a strongly failing grade based solely on the TPMS, which puzzles me. In spite of their marketing bravado, "The relentless Pursuit of Perfection", we need to be realists. Define perfection... Cars are far from being perfect, and we all have a different interpretation of that assertion. However, some of the best measurements we have at our disposal, are the ratings published by JD Power or Consumers Guide and other trusted organizations, and on that score Lexus rates near the top in many categories. Perhaps better monitoring systems will evolve over time, just as they did with Edison's humble light bulb. Hope springs eternal!

Mike_TX

But, Burnaby ... don't you have to admit that when technology of certain kinds is readily available, and in fact in use by lesser manufacturers, it's odd that someone like Lexus chooses to cheap out and use inferior stuff?

No, a TPMS system isn't enough to disqualify a car, or many of us wouldn't own one today. But add the primitive Lexus TPMS to the primitive Lexus voice recognition system, the Lexus navigation system that is far surpassed by others, etc., and one has to begin wondering why Lexus isn't firmly in the 21st Century along with other carmakers, especially in their flagship sedan.

The LS is a great car, no question, but Lexus needs to do a lot of catching up on the "extras" that make driving these nice cars more pleasurable and engaging. We are in the Information Age, and yesterday's info systems are obsolete.

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