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PJSMITH
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Discussion Starter · #1 ·
Has anyone experienced a tire press warning when driving and it goes off after a while.
I had checked the tires and pressures were good all around 35 cold. Temp outside was about 48F.Yesterday.
In Yellowstone driving at posted speeds the warning came on.
Temp was about 42F and the rise in altitude over an hour of driving was to 7800 FT and the light came on.
About 2000 ft rise.
Stopped and the tires were all even at 39psi
Could the altitude change the pressure that much to light off the warning.
Was the temp so cold that it changed and lit the warning.

I normally have not been in cold temps while living in San Diego and the temp was cold.
But the altitude added. Was it just the "perfect storm"?

The light shut off on it's own after we dropped back to the 5500Ft level with not notice.

This also happened a second time driving today. Similar that it was 45F and altitude was about 6K and it shut off at below 5000FT.
I stopped at a dealership to check because the warning said to check the sensor system.

The dealer checked pressures and said all was perfect and did not have a warning code.

Just checking to see if anyone else has had this happen. Or any engineers have the temp and pressure charts to back up my theory?
 

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Premium Member
2021 Avalon XSE Hybrid
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+1 on a sensor maybe going bad... or possibly an issue with the TPMS computer.

I had intermittent lights on my '16 Corolla. Maybe once every 2-3 months the light would come on. I'd stop and check, and all tires were fine. Restart, the light was off.
I upgraded the head unit to a Pioneer and added a Maestro unit that provided a direct readout, and sure enough, intermittently, one of the sensors would drop by 30-psi. It was typically a short enough event that it would not trigger the light, but it was frequent enough that I could not leave the HU set to automatically switch to the TPMS screen on a fault, because this would happen 3 or 4 times every hour.

I figured it was a flaky sensor, so when I replaced the tires, I had the sensors replaced as well.
Nope... Same problem remained, and incidentally, always on the same "corner"... right rear.
I never did resolve the issue, but the TPMS light stopped coming on shortly after I replaced the HU, so I just lived with it and manually checked the TPMS screen twice a day.
 

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2008 Toyota Camry Base / CE
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+1 on a sensor maybe going bad... or possibly an issue with the TPMS computer.

I had intermittent lights on my '16 Corolla. Maybe once every 2-3 months the light would come on. I'd stop and check, and all tires were fine. Restart, the light was off.
I upgraded the head unit to a Pioneer and added a Maestro unit that provided a direct readout, and sure enough, intermittently, one of the sensors would drop by 30-psi. It was typically a short enough event that it would not trigger the light, but it was frequent enough that I could not leave the HU set to automatically switch to the TPMS screen on a fault, because this would happen 3 or 4 times every hour.

I figured it was a flaky sensor, so when I replaced the tires, I had the sensors replaced as well.
Nope... Same problem remained, and incidentally, always on the same "corner"... right rear.
I never did resolve the issue, but the TPMS light stopped coming on shortly after I replaced the HU, so I just lived with it and manually checked the TPMS screen twice a day.
I believe nearly all the threads here related to (direct) TPMS issues are in the wheel. TPMS ECU issues seem to be uncommon.
 

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2021 Avalon XSE Hybrid
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The TPMS system will trigger a light under one of two conditions:
1 - One or more tires are below the set point... typically 28psi
2 - Any one tire is more than 10psi different from any other tire

Since all of yours were at 39psi, that is both well above the set point, and all tires were the same pressure, so the problem is in the hardware somewhere.
 

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2021 Avalon XSE Hybrid
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I believe nearly all the threads here related to (direct) TPMS issues are in the wheel. TPMS ECU issues seem to be uncommon.
Exactly why I thought the problem was with a sensor, but it wasn't.
Even after rotation and resetting the corner, the problem remained on the same corner of the car.
That would not normally be visible since the '16 Corolla did not have a psi display option from the factory.
 

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2013 Toyota Avalon Limited W/Premium Package +
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Many things can set off the warning. Improperly set pressure threshold. Interference, Temp of tires. Low and failing battery will cause sensor to not always wake up and report to duty. That will trigger a 30+ second flashing before solid light when it hasn't reported to duty after 30+ minutes and sometimes set a TPMS DTC which can't be read by a standard scanner. If the originals sensors on a 2014 one might be going. But with 315mhz signal many things can cause interference and set the light off for nothing. When my right rear sensor battery was between low and dead it would sometimes not wake up and trigger the warning and slowing down or pulling over to manually check tire pressure the light would turn off.

I needed 4 for my new winter rims and 4 for the OEM wheels (when one goes chances are the others will follow) and the timing was perfect since the tires had to come off the OEM wheels to get them refinished so I bought an Autel MaxiTPMS TS-508WF kit with 8 programmable sensors with both metal and rubber stems. That gives me rubber valve stems for my winter wheels and metal stems for the OEM once refinished and a really cool and easy to use tool. Way easier to diagnose than the TS with laptop and Now I have 4 spare rubber and 4 spare metal valve stems just in case. For less than the price of 8 sensors. Cleared the stored DTC and only 1 PSI difference between my digital tire inflator gauge and the sensor pressure reported. I know my gauge is around 1/2 PSI off so close enough in all. No such animal as a perfect gauge or sensor reading. There's a % of variance.
 

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Short List:

The threshold is 25% under set pressure. I don't think the Toyota sensors will set off a warning when overinflated under the sensor's designed max PSI threshold.

If it's hardware related the light will flash 30+ seconds then light solid.
If it flashes 3 times or doesn't flash and the light goes solid a sensor is reporting a low pressure warning.

If an interference object is installed between the sensor and the antenna on the lo-line (no positional display) it can prevent the sensor's transmitted data from being read by the module.

The "reset/relearn" button when used and improperly inflated tires it will set the threshold to 25% of that tire pressure. There is no reason for it. Toyota has a flaw that will lock the ECU in and endless loop and the major cause is that button.

Bluetooth devices, phone charger and other things can also create interference with the system. Driving by something that generates electro-magnetic interference can also cause TPMS false triggers.
 

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2018 Avalon XLE Premium V6
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I think it was a "perfect storm". Did you do the last threshold reset yourself or did someone else?

Two things set off the light under normal opperation:
  • pressure below threshold
  • low battery
Low battery can only be determined by reading the ecu with a capable scanner or TechStream. If the battery is low, replace the offending sensor.

Pressure below threshold is more nuanced. When you go up in elevation the air pressure in the atmosphere decreases. This will cause a commensurate decrease in the tires. It's not much but it does happen. Pressure also drops at lower temperatures. If the pressure threshold happens to be crossed, the system will be set off. You didn't say whether or not you have done a threshold reset. Do it (and do it correctly). Here's why... If the thresholds weren't previously set correctly, the light will go off at an inappropriate time.

To set the thresholds correctly the tires must be cold and at the correct pressures. I suggest doing it in the morning. You'll need to do some set up the night before by slightly over-inflating them by about 5psi. In the morning, slowly release just a little air at a time until you reach your target pressure (Toyota says 33psi for 18" and 35psi for 17", but you may choose a different target). Once you've got all 4 tires at your target, perform the reset. The Toyota Owner's site didn't have a copy of your full manual a couple of minutes ago so here's a excerpt from the 2013 manual on the reset procedure:
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The light should turn on at ~15 to 20% pressure drop (I calculated that percentage by doing the math on my measured and threshold pressures in TechStream immediately after doing a reset). If the pressures were high when it was last reset, you will have less than a 15% margin. For example: If the reset was last done when one of the tires was at 45 psi, the light would come on for that tire at ~36-38 psi. My experience has been that tire shops and dealers like to set the pressures high. I think they do this to decrease the chance of a customer complaining that the light has come on. Unfortunately, if they actually do a reset while at this higher pressure and then you later adjust to the correct pressure your light will come on sooner than it should. If you choose 35 psi as your desired pressure, the light would come on when you drop below ~28-30 psi.

Anyway, I suggest going through the reset to at least remove an improperly set threshold as being the cause of your increased elevation situation. Besides, it's free and it's easy to do.
 

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2013 Toyota Avalon Limited W/Premium Package +
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I think it was a "perfect storm". Did you do the last threshold reset yourself or did someone else?

Two things set off the light under normal opperation:
  • pressure below threshold
  • low battery
Low battery can only be determined by reading the ecu with a capable scanner or TechStream. If the battery is low, replace the offending sensor.

Pressure below threshold is more nuanced. When you go up in elevation the air pressure in the atmosphere decreases. This will cause a commensurate decrease in the tires. It's not much but it does happen. Pressure also drops at lower temperatures. If the pressure threshold happens to be crossed, the system will be set off. You didn't say whether or not you have done a threshold reset. Do it (and do it correctly). Here's why... If the thresholds weren't previously set correctly, the light will go off at an inappropriate time.

To set the thresholds correctly the tires must be cold and at the correct pressures. I suggest doing it in the morning. You'll need to do some set up the night before by slightly over-inflating them by about 5psi. In the morning, slowly release just a little air at a time until you reach your target pressure (Toyota says 33psi for 18" and 35psi for 17", but you may choose a different target). Once you've got all 4 tires at your target, perform the reset. The Toyota Owner's site didn't have a copy of your full manual a couple of minutes ago so here's a excerpt from the 2013 manual on the reset procedure:
View attachment 351364

The light should turn on at ~15 to 20% pressure drop (I calculated that percentage by doing the math on my measured and threshold pressures in TechStream immediately after doing a reset). If the pressures were high when it was last reset, you will have less than a 15% margin. For example: If the reset was last done when one of the tires was at 45 psi, the light would come on for that tire at ~36-38 psi. My experience has been that tire shops and dealers like to set the pressures high. I think they do this to decrease the chance of a customer complaining that the light has come on. Unfortunately, if they actually do a reset while at this higher pressure and then you later adjust to the correct pressure your light will come on sooner than it should. If you choose 35 psi as your desired pressure, the light would come on when you drop below ~28-30 psi.

Anyway, I suggest going through the reset to at least remove an improperly set threshold as being the cause of your increased elevation situation. Besides, it's free and it's easy to do.
That's good advice except for one potential problem: If there is a sensor that doesn't respond in the 10 minute window after doing the procedure you'll put the system in an endless loop and the ECU in a locked state.

EDIT: When doing the following manual test. The car must be started and driven to wake up the sensors and also left running while deflating to verify if and when the light comes on!

Another no tool method is to inflate tires to door jamb pressure cold. Drive for a little bit and come home. Deflate one tire at a time, 2 PSI max each time wait 30 seconds or so and determine at what pressure your light comes on. if it comes on too high or too low then someone did the above mentioned procedure with incorrect tire inflation. If you get down to 10 PSI your sensor or something else is at fault.

BTW: This is not a tire gauge. It's as useless as a visual inspection or kicking tires.
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PJSMITH
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Discussion Starter · #11 ·
Today it came on again. After checking and setting pressures in the AM. Temp 42F. Set at 35PSI
After about 30 minutes of driving the warning flashed and then went solid and there was no driving difficulty and nowhere to pull over or check for about 35 miles. Driving in the back roads of Montana, Idaho and Nevada.
When I found a place to stop, the light was still on and I checked the pressures with a good quality gauge and all 4 were at 39PSI (Hot?) even tho the temps were 48 and had been driving in rain and sleet.
I believe the sensor detected (starting) temp/PSI and altitude made the tires rise in pressure more than at lower altitude. Not sure about the science of it but something triggered it.
All three times it came on were after 30-40 minutes of morning driving and the warning cleared after cooling down (stopping driving) or the altitude changed.

****Does anyone KNOW the upper limit on the sensors to trip the warning?
I now think, but do not know that the high temp was the warning trip.
****

Since all of the tires were same pressure before and after all driving and there is no differential between the tires, it's not a low PSI warning.

As for the battery it could be bad in a sensor and when I return to SD I will have the batteries changed if this persists, first.. And then get analysis of the computer if necessary.

I did get the system checked for a cade at a Toyota dealer the first time and there was no residual and the warning stopped on it's own. Since the light doesn't just stay on, it is not a disastrous warning.
Since the tires have been checked twice daily and have no differential, the car should be fine to finish the trip/vacation.

I expect that the tires are reaching the limits of tread wear after another 1200 miles, so will probably get new rubber after we return.
Change the battery in the sensors when we change the rubber and should be a new test of the system.
 

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The 30 minute delay is the average timeframe when the ECU realizes that a sensor hasn't sent back any info and initiates the warning procedure. I'm assuming that the warning light flashed for about 30 seconds before staying lit solid?
If so I'm quite sure it's a sensor. You have a 2014 so no position display. The car doesn't know or care where the tire is so rotation won't change anything.

Sensors are sealed for logical reasons. You can't just replace a battery... well you could but that is a long and useless hack job and I doubt whoever does the removal and install will wait for a couple days for you to have fun trying to replace 4 sensor batteries. You replace the complete sensor when the battery dies. If you want to know how "FUN" replacing a battery is in a sensor ask the tech to give you an old one and you can try and see what it's like, Ig you tell him why you want an old sensor he might smile or laugh. When one goes the others aren't far behind especially if they are the originals. So you replace them all. 39 PSI will not trigger anything, When hills are involved or mountains the braking will increase the brake temps and the tire through the rim through dissipation increasing the PSI. So very normal and some people actually inflate to 40 PSI.

If you need new tires then you couldn't ask for a more perfect timing.
New sensors in all 4 wheels at the same time.
 

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2021 Avalon XSE Hybrid
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****Does anyone KNOW the upper limit on the sensors to trip the warning?
I now think, but do not know that the high temp was the warning trip.
I do not know if the temperature will trigger the light. I've never encountered that happening in temperatures from 40 up to (sensor temperature) over 140.
AFAIK, it is only monitoring pressure.
The top limit is not the issue. I ran my Corolla at 45psi and the system was happy as a clam.
I run my Avalon at 38 cold, it hits 44 after an hour on the freeway. Wife's Venza runs about 40 cold.
Some light truck and SUV tires are designed to run at 60+, they use the same sensors.
 

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2021 Avalon XSE Hybrid
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Can Carista display the sensor pressure temp on the '14?
Might be worth having a BT dongle and pay for a month on the program to have it available for the next time it happens.
If a sensor is dropping out, that should show what's happening, but otherwise, the lithium cells used in the sensors have about a 10 year shelf life, anything over 5 years they may be simply dead.
Manufacturers probably assume that you'll change the sensors with the tires, and for most drivers, that's probably a good time to change them.
 

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The lo-line sensor reports ID, Pressure, Temp and Battery status.

This is why I love my TS508WF. Point trigger and read. This is just basic mode.
Pressures are low as it was hot when they were installed. And the spare I don't have a sensor (donut) and triggered the right rear twice accidentally. Was checking the gap between my digital guage and my sensors. When I go back for my summer wheels I'll try and see how my gauge compares with the shop's. Then compensate accordingly. I think my gauge reads 1/2 PSI higher and sensors 1/2 lower. Hence the 1PSI (more or less difference) since I inflated to 33 PSI before scanning.


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BeerSteakTxas
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... the warning flashed and then went solid
Flashing turning to solid light means no communication with a receiver. Most likely the battery is low and the sensor need to be replaced.
During summer temps and stop and go traffic my TP goes to 43-44 psi sometimes and that never triggered the light, so I believe there is no upper limit.
 

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If there is a sensor that doesn't respond in the 10 minute window after doing the procedure you'll put the system in an endless loop and the ECU in a locked state.
Good information to know.

I was not aware that any of the 4th Gen Avalons were susceptible to the "loop" issue that occurred on some of Toyota's previous models. I have a copy of the TSB for the 2007-2009 Camry that covered how to get it out of the "loop" if it should occur (a simple jumper in the OBD-II port would release the loop). I was not able to find a TSB for the Avalon (4th Gen). Do you have a copy of it?
 

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Good information to know.

I was not aware that any of the 4th Gen Avalons were susceptible to the "loop" issue that occurred on some of Toyota's previous models. I have a copy of the TSB for the 2007-2009 Camry that covered how to get it out of the "loop" if it should occur (a simple jumper in the OBD-II port would release the loop). I was not able to find a TSB for the Avalon (4th Gen). Do you have a copy of it?
I figured I'd post my findings since TPMS systems and sensors seems to be misunderstood by many and I was one of them and I hate dealing with something without understanding how it works. I'm no expert but this is what I have learned in a nutshell.
All info relates to direct TMPS systems only (have a sensor in each wheel)

1 - The TSB in question is from 2009 and Toyota isn't the best at updating.

2A - Good information is HARD TO FIND! And Toyota isn't the greatest at supplying proper information and updating it on an ongoing basis. Same as not dealing with issues until they have their neck in a noose. Flaws are usually referred to as an "As designed" feature.
2B - Incorrect information though is SO EASY TO FIND and often the first 200 results are in that category (I just used 200 randomly. We all know bad info is easy to find and too often is in the top search results)

3 - Real life results are easier here is a post from TN involving a 2010 Camry. Which confirms 2 things. A: The jumper unlock isn't as simple as most people think and B: The ECU will lock on a 2010 and hence proof that the problem did not end with the 2009 TSB models. 2010 Camry TPMS ECU Loop Lock? | Toyota Nation Forum

4 - The Toyota direct TPMS system is basically the same with some minor variations from 2007 to 2019. Different sensors with minor protocol changes but pretty much all the same ECU and module functionality. All models without auto relearn like your 2018 has, are OBD relearn. There could be some exceptions but I can't be bothered researching every model and year Toyota produces. Logic and the operation mode leads me to the conclusion that if they have a "set" button and it is pressed when all 4 (or 5) IDs are not reporting or before the relearn procedure has been done correctly the ECU will lock and entering new codes will be impossible without unlocking the ECU. Hence the reason Autel has added the Toyota unlock function as an automatic first step to the all their OBD capable TPMS tools when performing a relearn procedure. In the TS508 it was a separate option in previous software versions and after too many CS calls they've eliminated all these calls from the queue by just doing it automatically.

Defining the correct terms for each function:

Programming: This is the process when a blank programmable sensor (specific or universal) is programmed with the communication protocol for a specific vehicle and assigning it an ID. The term is incorrectly used to describe the relearn process by the majority of "professionals" and owners.

Relearn: This is the correct term and not "program" to describe the process of storing the correct sensor ID(s) into the ECU so that it knows which ones are installed. There are 3 possible methods. Stationary, OBD and Automatic. All makes have different steps and procedures to accomplish it. All Avalons to 2019 with TMPS without the positional display to 2019 are lo-line and are OBD relearn only. The 2016-2019 that have a positional display are hi-line and have both OBD and Auto relearn capabilities.

Set/Reset: Many Toyotas (other brands are irrelevant to me since I own a TAL) have a button under the dash or in the glove box. It should only be used when a different inflation pressure is used for example if you decide to put 17" wheels on an Avalon that has 18" wheels the pressure is 35 for 17" and 33 for 18" wheels. When pressed until the light blinks 3 times it will wait for each sensor with the ID stored in the ECU to report current inflation pressure. If after a certain amount of time (I believe it's 10 minutes) all sensors have not reported back the famous ECU lock loop will occur. If all is well it will store the current readings as the reference.

Rotating tires on a lo-line (light warning only) does not require a relearn or a reset procedure as the car has no idea where the sensor is and only cares that it's on the car and working. And there is no need to change the tire pressure threshold using the SET button.

BASIC DECODING OF THE FAMOUS "HORSESHOE" TMPS WARNING LIGHT
(It's supposed to be a tire but it actually does look more like a horseshoe LOL)

Flashes 3 times on ignition and turns off: System functioning properly (not sensors only the vehicles components)

Flashes then stays lit on ignition: Low tire pressure detected by comparing set threshold and reported pressure from at least one sensor. Can also be caused by improperly set threshold.

Flashes continuously for 30-60 seconds on ignition and stays flashing or lights solid: There is an issue with a component on the vehicle side (not usually the sensor)

Flashes 3 times, turns off and off you go... 30+ minutes of driving and the light flashes for 30+ seconds and comes on: Stop and restart car and all seems good till the time delay has elapsed and the same thing happens again. A weak sensor battery might report and not set the light every time (yet) One or more sensors has not transmitted it's data during that period of time. Sensor battery is low or sensor is dead. If more than 5 years old replace all sensors at the same time. If recently replaced sensor(a) first confirm that none are visually broken and that the relearn process was correctly done.

The period between reporting as OK to low then dead on these batteries is quite fast. A low means get them changed ASAP and check your tire pressure frequently. Also never assume the light off means tire pressures are OK. From what I have read the threshold is 25% to set the light off. 1PSI above it and the light stays off while you drive your expensive tires and wheels under inflated.

Hope this can help someone.... somewhere... someday.
 

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2014 Avalon Limited
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Sounds like tires and 4 new sensor's are in your future. Not that big of a deal for a 7 to 8 year old Avalon nearing 100,000 miles. It's a nice safety feature when the tire is really low on air. The colder weather can depleted just enough of the tpms battery life to trip a borderline tpms battery. You will be fine . Enjoy your trip home.
 
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