Dolphin

I installed an OBD II BT dongle to my 13RX350 computer port (near steering column).... all works well, but it seems tire pressure does not register on any of the Android apps I downloaded. Anyone know how to access the tire pressures?

For those unaware, its a dongle you plug into the computer port of car, and your phone or tablet, can display nearly all pertinent data on a dashboard that you design for your liking, example screen below...

vlad_a

The tire pressure may be a 450h feature. We have it available to be displayed on the cluster, while the 350 doesn't. I figure the data is not exposed or not measured the same way.

Dolphin

the 350 monitors tire pressure and alarms us if pressure drops below the mysterious threshold value......therefore, the tire pressure has to be in the cars brain somewhere... I realize its not going to appear on the cluster, hence why I bought the OBD dongle, so I can display all the 350's missing cluster data, such as Voltage, Oil Pressure, tire pressure, etc.

vlad_a

It may be monitoring all 4 wheels and is looking for one or more out of range with the others. I know it monitors it somehow - it is mandatory in the US, after the whole Explorer fiasco.

BTW, I noticed 450h even has a sensor in the spare tire, as it was picking up one reading of 60PSI when I had winter wheel set on. I don't bother with TPMS for those.

bill77056

Thanks for posting. I must check to see if this will work with a 2010 RX. It is nice to actually see the tire pressures - my 05 Tahoe does this and it has saved me more than once by showing a low pressure tire.

Dolphin

Oh, it will work with your RX... and it's cool for sure, the more apps, the more cool things you can do. I like the feature that allows you to view a trip, showing fuel economy the entire route... certainly not mandatory, but definitely neat toy



but I learned on the ScanNet forum (which is the make of the dongle I bought on Amazon, ScanTool $149), OBDII dongles only cover engine / emissions. Argggg....

Hard to fathom in 2013 Lexus doesn't let give us a scroll-through feature in the dash cluster, for information such as tire pressure, voltage, oil pressure, etc. Seems in some ways, they miss the most obvious things, which would are not costly to display, heck, cars costing half this much offer these features years ago. Maybe it was another feature that Lexus decided to take away through the years.

Vlad, yep, I have read this a few different places, sometimes tire pressure is monitored by changes in the differential, as, lower tire pressure = smaller diameter, drag on the differential...so the low pressure alarm, could be a "relative pressure" drop through this calculation, vs. an actual psi sensor inside the tire. At least for the 350, 450's seem to have real pressure sensors in the tires. If this is the case, arggggg... did not think I would have to buy aftermarket pressure sensors for tires on a 13 Lexus...this is what happens when one "ASSumes"....

vlad_a

It doesn't look like going aftermarket is going to help.
Sewell has the same TPMS sensor part number for both 350 and 450h:
http://lexus.sewellparts.com/accesso...2013/4529.html

Personally, I wouldn't worry much about it. I guess I must be old school - grab the tire gauge and the compressor and set the tires to the desired pressure. If I had an option of not getting TPMS, I sure would not. It becomes a hassle, especially with 2 sets of rims and incurred cost.

Dolphin

Interesting, so the same pressure info (350+450) from each tire is being fed to the computer... now, need a way to extract it. I find this a must-have feature, as more roll overs on freeways occur due to loss of tire pressure vs. accidents or falling asleep....the alert system seems to "after the fact" for my taste...if I suspect something, I would like to check the tire pressure on the fly...vs. stopping, getting a gage and checking 4 tires in the rain, snow, wind, side of road, etc. ...

vlad_a

Well, you will know if a tire is running low. The car will handle differently. It will start wobbling if the rear tire is going or the steering will get spongy in the front.

I had a rear 16" tire (55 profile) blow out on my IS when I hit a sharp object on the freeway. And nothing happened. Really. I just kept driving, in the snow too. Took the exit and parked the vehicle. No drama whatsoever. Took the wheel off and found a big hole in the tire and a crack through the whole rim.
When a 17" low profile deflated due to being worn out, again, nothing major had occurred. I pulled over and put a spare on.
Had another rear go out on a full size van fully loaded with cargo. It started wobbling and I pulled over. That one I definitely felt, but at no point was I loosing control.

None of the above would have been prevented by TPMS. IMHO, there is no way tire pressure drops are causing accidents at such a rate. Just stay away from Explorers running on Firestone tires. I have seen one of those hit the wall.

If it is a concern, a run-flat tire would be a much better option. Those will keep their shape and will keep going.

BertL

Dolphin. Don't get too excited. While the RX450h can show the tire pressure of the 4 tires using real TPMS, it shows 4 numbers in a row, and you don't know which one goes with which tire as nutty as that is -- so even if some OBD program was written to get to the numbers if they are accessible, who knows if it could tell which tire it was for. If the TPMS monitor goes off in my 450h that pressure is low, you can use the display accessible from the steering wheel to see one of the tires is at some low PSI, but then have to stop and whip out a real pressure gauge testing each one to find where the problem tire is.

As a side note, and eluded to by other posters, TPMS implementation is not a requirement in all countries, and implementations vary widely. E.g., I found just yesterday that MBZ does not have real TPMS on their SLKs in the UK or Canada, but does for those in the US... and my to-be-new SLK will show the pressure for each tire, such that I'll know which number goes with which one. How wonderful. Those smart Germans. ...and Dolphin, to your earlier point, I can provide concrete proof that MBZ does the "reducing pressure approximation" method you describe on their SLKs in countries that don't have real TPMS implementation, such as the UK. I'm learning a lot about some of these country-difference things participating on a primarily European forum about my new SLK, and find it all very interesting how auto mfgrs have to abide by so many different country laws, and therefore sometimes create completely different implementations for things we take for granted... Not just different hardware/software for some countries, but all the supporting customer and service manuals. I'm finding headlights are another big difference in what is and is not offered and deployed in varying countries. It sure makes one wonder if its more costly to manage all the variations or to have one standard deployed that would work around the globe... if such a thing is even possible. Hopefully the mfgrs are making the best decision to hit the right price points in eqch geo while providing maximum functionality for us all... . ...but my new found knowledge at least in part explains perhaps why the TPMS implementation on my 450h is incomplete from my perspective -- I'm confident it meets federal requirements, but still hope Lexus catches up with their German competition in their continuous pursuit of perfection. I hate having my Lexus outdone by MBZ with something that would have taken just a little more work to fully deploy and then have become a non-issue we would not even be discussing here.

Dolphin

Everyone puts different value on safety issues. Often this is based on your experience, as you have expressed in your post. You have concluded based on your limited experience, tire pressure monitoring is a non-issue. You have also concluded that loss of tire pressure is always noted by a change in the cars reaction... this is not always true, as often it can happen quite fast, long before you suspect a problem. Its easy to confuse road noise, wind, etc, with a short 10-20 second tire issue.

I base my positions on a good friend who spent 20 years on Highway Patrol... watching 2-5 SUV non-accident rollovers per week, due to tire issues, including blow-outs, which often occur as tire pressure drops quickly at high speeds. He is the most vigilant tire pressure control freak I ever met... I am following his safety lead. I wanted to simplify tire pressure monitoring...u would think in the year 2013 this would be standard feature on a Lexus, but, obviously not... gotta read the fine print...as in theory, the RX is monitoring tire pressure.

Bert...arggggg... encrypted read-out of tire pressure? huh? u gotta be kidding me? (I know ur not) Once again, its frustrating when you can buy after-market kits that do all this so well for relatively low cost. But who wants all these after market gadgets all over your dash when this is simple technology that should be integrated into a cluster read-out... frustrating for sure... Glad the SLK offers this in a usable fashion...

kryten

My 2010 Acura TSX I had showed the pressure per corner on the dash overlaid on a car graphic. I do miss that! It has always annoyed me if a car has TPMS but does not show you which corner is low on pressure and how low it is!

Dolphin

Kryten, fully agreed, this all seems so simple to implement in our modern electronic era. I too would miss such a feature, specially if you upgrade to a much newer luxury car.

Long ago, I put one of these after market TPM kits on my Motorhome...it worked great for a few years, till one of the caps failed, and it created a flat. Hence why I wanted a factory system vs. these after-market generic systems. You would think factory systems are more reliable. Hopefully technology has improved.... all these after market products are a crap shoot...
Here is a sensible unit (Hawks Head system) which looks quite small, and shows all 4 pressures in a sensible layout. $245 with shipping in N.A. For an extra $40 can have it display the spare tire pressure as well, although no pix of where its displayed...

vlad_a

Dolphin,
TPMS is not a means to an end of a tire blow-out issue. It will let you know if a tire has been running low. A tire with low pressure will not necessarily cause a blow-out. Even if it deflates rapidly, the vehicle will not roll over. If you don't believe me, keep an eye for vehicles on the side of the road that have flats. How many of them are parked on their roof?

TPMS is intended to prevent a very specific problem from reoccurring, as it has in the past. Ford Explorers were prone to roll-over in panic maneuvers, so the engineers had them running at low tire pressure (26 PSI) to somewhat mitigate this problem. However, a very specific 15" tire manufactured by Firestone, did not react well to this change. The sidewall disintegrated and entire tread separated. Other brand of tires (Goodyear) did not have this issue.
http://en.wikipedia.org/wiki/Firestone_and_Ford_tire_controversy
I came across a moose test video for Jeep Cherokee in this forum. Don't mind the test itself. What is interesting is that they show the front tires pop 6 times during this test, yet the vehicle does not get unstable or looses control more than it would otherwise.

If your tire is suddenly deflating, you may never get a warning from TPMS. To preserve battery life, the data is sent in intervals and it takes a while for it to register.

IMHO, a larger size rim along with run-flat-tire would address tire blow-out safety concern much better. I'm not saying get rid of TMPS, just that by itself it has limited use and should be treated as such.

Dolphin

>A tire with low pressure will not necessarily cause a blow-out. Even if it deflates rapidly, the vehicle will not roll over.'

maybe, and maybe... lots of variables here, too many to mention... my point is, this is relevant information for safety. You are discounting a high speed blowout that creates a quick steer into close cars, causing an accident. So maybe I should have mentioned accidents as well, not just blow outs and roll overs. Yes, I have seen that Jeep video many times...its different going 80 mph though....

> If your tire is suddenly deflating, you may never get a warning from TPMS. To preserve battery life, the data is sent in intervals and it takes a while for it to register.

This is a valid point vlad :-) I just got an email response from the company.... updates are every 4 minutes, but ALARMS are sent immediately, no delay. User settable low pressure value. Nice feature, this is what I would think Lexus would offer, but no dice. Certainly not complex or costly to implement.

I do have 19" rims, that helps for sure. As for run flat tires... I prefer the feel and shock absorbing ability of inflatable tires. Remember here, this is a very low cost safety enhancement feature. It's not $2k, its $200 :-) And IMO, it offers a lot of safety value for the cost. I still find it hard to fathom its not built into the car... I will prob. order it.