TPMS Sensitivity

Whiplash Willy

New member
I got a nail in my tire and am running my spare while I wait on a new tire. I am surprised at how long the TPMS system takes to give me a light that is an issue (no TPMS in spare)

It takes about 30 min of driving before the light comes on. I would imagine that with a moderate leak the TPMS wouldn't notify you in time. I figured with fancy TPMS sensors in the wheels it would notice an issue quicker... My VWs abs based TPMS even seems more responsive.

When hooked into TIS I can see real time fluctuating PSI values for my tires, so the sensors do keep the system constantly up to date, I just wounder why it takes so long to update the driver.
 
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It took 30 minutes after you got a nail? Or it took 30 minutes after it was flat? When I air down to go off road using Staun tire deflators (1 for each wheel, deflate tires in about 2 min) the TPMS is on when I get back in my Truck.

David
 
Did you check to see how many PSI was left when it finally came on? I've read on here that the TPMS light comes on ~26 PSI, so it's very possible that a nail puncture would leak slow enough for it to take that long to finally lose enough pressure and trigger the warning light...I've had nails in my tires that have gone unnoticed by me for months because sometimes they just leak so slowly, lol.

I can assure you the TPMS system is not too slow to react if you actually got a nice sized puncture. Once I picked up house key right through the treads (don't ask me how this is even possible) and the light came on early enough for me to pull off the next exit, and slap on the spare without ruining my tire by driving on it under inflated. By the time I had the jack out of the trunk the tire was completely flat, so you can imagine how fast it was leaking out.
 
It took 30 minutes after you got a nail? Or it took 30 minutes after it was flat? When I air down to go off road using Staun tire deflators (1 for each wheel, deflate tires in about 2 min) the TPMS is on when I get back in my Truck.
This. I will put my deflators on and get back in the truck when it's cold (or mosquitoes out), and the TPMS light is always on within a few seconds of getting in.
 
I got a nail in my tire and am running my spare while I wait on a new tire. I am surprised at how long the TPMS system takes to give me a light that is an issue (no TPMS in spare)

It takes about 30 min of driving before the light comes on. I would imagine that with a moderate leak the TPMS wouldn't notify you in time. I figured with fancy TPMS sensors in the wheels it would notice an issue quicker... My VWs abs based TPMS even seems more responsive.

When hooked into TIS I can see real time fluctuating PSI values for my tires, so the sensors do keep the system constantly up to date, I just wounder why it takes so long to update the driver.
the spare should also have the sensor.

maybe it took that long for the leaking tire to get low enough to set it off.
 
Eddie's post is correct. I just had to deal with a tire with a fast leak.
The TPMS is very sensitive and works just as it should.
It will only go off after the tire is under a certain psi. I believe that psi is 26...
If its 27 or over, it will not go off.
 
[MENTION=52619]Whiplash Willy[/MENTION]

This would be very easy to test. Get a gauge, be near a compressor, deflate to 25-26# and see what happens.

If you are concerned about your tpms' accuracy, test it. easy peasey.
 
Sorry for my confusing post...

The tire got the nail in it, holds air, and is at proper PSI, however, I don't' trust driving on it until the tire is replaced, so I put my spare on for the time being. The nail is too far to the side to safely patch....

America's tire hooked me up and got Bridgestone to get me a new tire for free, as long as I buy road hazard for all of my tires. So for $108 I am getting a new tire mounted, and a warranty for my others, since I seem to like to run over nails... I am pretty happy for that. I also got them to confirm the weight of the Cooper ATP (P-Rated) for the OEM size, which is 41LBS, incase anyone wanted to know.

So, I put on my spare, which is a steel wheel, with a rubber valve stem (No TPMS). So I am now driving with 3 TPMS Sensors. It takes 30 min of driving now before the TPMS system notices there are only 3 of them. Maybe it is more sensitive to losing PSI, then it is to a missing TPMS sensor. I will try the air down test though to make sure my system isn't defective. It is good to hear from others, that it picks up low PSI quickly.
 
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I have read from other members here that it does take quite a while for the TPMS ecu to realize that sensors are missing...I think someone here posted that they thought the shop had put in and programmed a new set of TPMS sensors for "free" on some new wheels they installed, only to find out that it was just the light that was slow to come on, lol.
 
From what I understand, the sensor reports to the rec'r at certain intervals and/or conditions. The warning light came on because the sensor failed to report, not because it reported a low pressure situation. I have also heard that some sensors go into sleep mode when not in use. Not sure exactly how this happens but it explains why you sometimes get an error code after a tire has been serviced and the tech has not re initiated the sensor.
I'm still looking for a website that explains this stuff.

Edit: http://www.tirepressuremonitoringsystem.com/tire-pressure-sensors.html
http://www.toyotatpms.com/index.html
 
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From what I understand, the sensor reports to the rec'r at certain intervals and/or conditions. The warning light came on because the sensor failed to report, not because it reported a low pressure situation. I have also heard that some sensors go into sleep mode when not in use. Not sure exactly how this happens but it explains why you sometimes get an error code after a tire has been serviced and the tech has not re initiated the sensor.
I'm still looking for a website that explains this stuff.

I think I recall what you are talking about...I believe it was blackworksinc that explained this before. It was something along the lines that a new sensor needs to be "woken up" after being installed or else it might not start reporting the data. I think he had mentioned letting air out rapidly at a certain rate to accomplish this.
 
interesting. so it comes with a non-matching spare?

why would they go backwards like that?
According to the dealership service manager when I asked ,it was because the spare tire getting low ,mainly in winter, and setting off the TPMS light was the number 1 service call for them.I owned a 4th gen and never had it go off for the spare but then I did check it's air pressure regularly.The 5th Gen TPMS ECU won't even accept a 5th sensor now.

I personally think it was more of a cost trade off.Some things were cut to add other things and keep the cost about the same thanks to the bean counters.

Here were the things that are upgrades(trade offs) from 4th to 5th gens IMO having owned both.

Per Toyota...Extensive frame and body reinforcements with braces have been added using high-tensile strength materials(aka new LC J150 frame),reworked engine mounts and a completely newly designed and much stronger rear 8.2" 12 bolt differential were added in 2010 .That's where the majority of the 300lbs of added weight in improvements over the previous generation are if I were to venture a guess.

Improved interior comfort with higher h-point and better headroom

New Off-Road options: Crawl Control, Multi-terrain Assist, KDSS (Kinetic Dynamic Suspension System), Active Traction Control

Standard- Star Safety System 8 airbags, which includes new knee airbags and full side curtain air bags

LED Optitron gauges that take a page out of the Lexus playbook

Engine improvements.... https://docs.google.com/open?id=1VJY...JM6fxIHLu18VuE

Limited Edition has push button start with Smart key keyless entry

Rear Gate Speakers and a sound optimization mode for tailgate listening aka the "Party Mode" switch

Sequential shift transmission shifter

Puddle lighting underneath side mirrors/LED Turn signals in mirrors

120V AC power outlets, one in the center console and one in the cargo area

LED footwell lighting, interior door handle lights and shifter lighting from roof mounted console LED's

Windshield wiper and mirror de-icer

Rear view monitor system

HomeLink universal transceiver standard on all models

USB port located in glove box

A compass has been included on the accessory meter display

LED high mounted rear stoplights

Available Safety Connect

Active head restraints

Rear seatback angle adjustment(recline)

Auto up/down switches for all windows

Two 12V power outlets up front

Hidden rear wiper underneath rear spoiler, spoiler standard on all models

Inside door handle and switch lighting

All models use the 13.3" front brake rotors

10,000 mile oil change intervals using synthetic 0W-20 oil

Min. Running Ground Clearance 9.6", the increase over the 9.1" 4th gen

Probably left out a few and I admit they did delete some things from the 4th Gen that were insignificant to me and added so much more.That's why I bought another 4Runner as they keep making them better IMO,a 5th Gen and have loved every single minute of it! Still Smilin' every time I drive it and it's almost 4 years old now
 
According to the dealership service manager when I asked ,it was because the spare tire getting low ,mainly in winter, and setting off the TPMS light was the number 1 service call for them.I owned a 4th gen and never had it go off for the spare but then I did check it's air pressure regularly.The 5th Gen TPMS ECU won't even accept a 5th sensor now.

I personally think it was more of a cost trade off.Some things were cut to add other things and keep the cost about the same thanks to the bean counters.

that makes sense. on both accounts.

but, i do think knowing if/when the spare is low, BEFORE you actually need it would be good informatin to have. considering the system is already in place for such a thing.
 
I would like to see real-time readouts of each tire including the spare and different levels of warnings. Obviously, after reading the thread about having to hold the key too long to start the car, I think any kind of information like that is just gonna confuse people.
 

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