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Discussion Starter #1
An hour into my trip driving under "straight and level" cruise control conditions, the TMPS warning came on. On closer inspection I found a 1 psi difference between the rear tires. Even after the tires were cooled down the tire with the lower pressure was at 30.5 psi, the other side was at 31.5 psi. The fronts both registered 32.5 psi. Two questions: (1) Would the TPMS be that sensitive? (2) Would the OBDII data for TPMS identify the suspected tire?
 

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In my experience a true TPMS alert generally requires a pressure loss of 7-10 lbs (vs normal inflation pressure) in at least one wheel. This assumes the TPMS is calibrated for the current set inflation pressure.

You can sometimes get a false positive on this new passive TPMS used in gen5 CRVs. I got one early on.. freeway driving, mixed road surface, and curvy driving. I think in my case, something in the road convinced the traction control system to attempt to prevent a wheel slip... and that triggered it. I pulled off the road, checked my wheel pressures (all normal) and simply set the system to re-calibrate and it never gave me another alert.

I honestly do not know if TPMS alerts show up in the OBDII.
 

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Discussion Starter #3 (Edited)
Thanks williamsji. I guess it was also a false positive in my case. I have just placed my order for a BlueDriver. Will leave the TPMS alert on,investigate any potential TPMS reporting and provide the feedback here.
 

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@4WheelSpyder

Hello,
Below is some information on this topic, I posted in another discussion that I believe will help here as well.

Cheers!




Here is a partial reprint from a Honda Job Aid published in September 2017 (Version 2) to help clear up some misunderstandings and conjecture about indirect TPMS.

Indirect TPMS Calibration

INTRODUCTION

Indirect TPMS, first introduced in the 2013 Accord, provides the same function as direct TPMS but does it differently.

Here is what it covers:
  • A Few Basics
  • Calibration
  • Low Tire Pressure/TPMS Indicator Functions
  • Calibration Comparison Logic
A FEW BASICS
Unlike a direct TPMS, an indirect TPMS does not use tire pressure sensors mounted in the tires. Instead, the system is integrated into the VSA modulator-control unit and uses the following inputs to monitor and compare tire characteristics while driving and determine when one or more tires are significantly underinflated.
  • VSA/ABS wheel speed sensors
  • Yaw and G sensor
  • Brake pressure
  • Steering angle
  • Outside temperature (measured from the front bumper)
From these inputs, the system calculates tire pressures. To determine tire pressure loss, the system uses these two methods:
  • Wheel Speed Differential - This method is used to detect if one, two, or three tires have lost pressure. It compares the two left tires to the two right tires, the two front tires to the two rear tires, and the left front and right rear tires to the left rear and right front tires.
  • Peak Tire Resonance - This method is used to detect if all four tires have lost pressure. A good example: if the tire pressures have not been checked for over 9 months.
An easy way to tell which type of TPMS a vehicle has is by looking at the valve stems. Vehicles with indirect TPMS have black rubber valve stems. Vehicles with direct TPMS have gray alloy valve stems.

CALIBRATION
In order to calculate tire pressures, the system must first be calibrated. The system relies on the tire pressures being set to the cold inflation values listed on the driver’s doorjamb label and the calibration process started. This process must be done at PDI, and also at scheduled maintenance and anytime you do the following:
  • Adjust pressure in one or more tires
  • Rotate tires
  • Replace or rebalance one or more tires
Keep in mind if the Low Tire Pressure/TPMS indicator is not on, you just need to start the process; the system will finish it on its own as the customer drives the vehicle.

If the tire pressures are not properly set and/or the calibration process is not started at the right time, the tire pressure calculations are tricked, causing the Low Tire Pressure/TPMS indicator to possibly come on, resulting in a possible customer comeback and wasted troubleshooting time.
Starting calibration is very easy. Here is how it is done. You will also find these procedures in the PDI bulletins, owner’s guides, owner’s manuals, and service information.
Before You Start
  1. Make sure the vehicle is completely stopped with the transmission in Neutral (M/T) or Park (A/T or CVT).
  2. Make sure all of the tires are the same type and size. The system will not work right otherwise.
  3. Set the tire pressures to the cold inflation values listed on the driver’s doorjamb label.
  4. Turn the ignition to ON.
  5. See the owners manual on how to start TPMS calibration on the specific vehicle you are working on.
NOTE: The above steps vary, depending on the vehicle and how it is equipped.

CALIBRATION COMPARISON LOGIC
Whenever calibration is started, the TPMS control unit learns the tire characteristics during the calibration drive. Should those characteristics change for any reason from what it has learned (for example, there is a sudden drop in tire pressure), the Low Tire Pressure/TPMS indicator comes on as a reminder to check the tire pressures.
If the tire pressures are properly set and calibration is started, the indicator goes off, the control unit learns the proper tire characteristics during the calibration drive, and all is well. But what if nothing is done about the tire pressures, but calibration is started? The indicator will still go off, but now something called calibration comparison logic steps in.

The control unit then compares the tire characteristics that caused the indicator to come on to the tire characteristics during the calibration drive. If the control unit sees that there has been no change in tire characteristics, the indicator comes on again within 20 minutes as a reminder to check the tire pressures.

It is not uncommon for customers to experience this situation and, when they do, they are often confused and think there is something wrong with the TPMS and end up back at their dealership. Here is common a scenario:

The Low Tire Pressure/TPMS indicator comes on while driving. The customer, not wanting to stop and check tire pressures, starts calibration knowing it will turn off the indicator. The control unit’s calibration comparison logic sees there is no change in tire characteristics since the last calibration and the indicator comes on again within 20 minutes.

The truth is this scenario can easily be avoided by simply heeding the indicator and taking proper action (setting the tire pressures and starting calibration).

LOW TIRE PRESSURE/TPMS INDICATOR FUNCTIONS
The Low Tire Pressure/TPMS indicator does a variety of things, depending on conditions and circumstances.

Normal Conditions
  • The indicator comes on for a few seconds when you turn the ignition to ON. This is just part of the system check.
  • The indicator comes on for 2 seconds, then goes off, if the vehicle is not moved within 45 seconds after turning the ignition to ON. This just means the system is still calibrating.
Abnormal Conditions
  • The indicator comes on and stays on if one or more tire pressures are very low or the system has not been calibrated. If this happens, the vehicle should be stopped in a safe place, the tire pressures checked and adjusted as needed, and the calibration process started.
  • The indicator blinks for about 1 minute, then stays on if the compact spare tire is mounted or there is a problem with the TPMS.
    If the spare is mounted, the regular tire should be repaired or replaced and mounted as soon as possible, and the calibration process started. If the spare is not mounted, the calibration process should be started and the system checked.
 

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I recalibrate TPMS every time I check/add air, rotate tires, or have a flat repaired. I've never had a false reading since I started doing this.
 

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Thanks williamsji. I guess it was also a false positive in my case. I have just placed my order for a BlueDriver. Will leave the TPMS alert on,investigate any potential TPMS reporting and provide the feedback here.
You don't really need to scan the codes here. Since there's no component specific to TPMS, there's nothing to fail or replace. You just kick off a re-calibration and call it a day. I suppose there might be a code stored somewhere in the system, but it's almost certainly something generic and won't have any action other than "Verify tire pressures and re-calibrate."

I bought myself one of those aftermarket system with transmitter valve caps and a little solar-powered display that sits on the dash, and I feel much better than wondering if TPMS is going to catch a problem in time, and I can safely ignore false-positives until I have a chance to re-calibrate.
 

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You don't really need to scan the codes here. Since there's no component specific to TPMS, there's nothing to fail or replace. You just kick off a re-calibration and call it a day. I suppose there might be a code stored somewhere in the system, but it's almost certainly something generic and won't have any action other than "Verify tire pressures and re-calibrate."

I bought myself one of those aftermarket system with transmitter valve caps and a little solar-powered display that sits on the dash, and I feel much better than wondering if TPMS is going to catch a problem in time, and I can safely ignore false-positives until I have a chance to re-calibrate.
@sirwired
The logic for indirect TPMS lives in the ABS/VSA modulator and there is lots of supporting values provided in the TPMS data stream to help diagnose challenging TPMS problems (i.e. When the last calibration was started?, What judgment was reached by the TPMS logic to turn the TPMS indicator ON and store a DTC?, How many times it has been triggered, etc.).

But what you and others here have mentioned will solve or prevent the overwhelming vast majority of TPMS problems... start the recalibration immediately after performing anything related to wheel or tire maintenance!

DO NOT recalibrate just to "turn the light out"! This will only compound things and lead to deeper frustrations.

If the TPMS indicator is ON, it's trying to tell you something 👍🏼

Cheers!
 

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Discussion Starter #9
Thanks to all who have responded.

I just came back from the dealer. They hoisted the car and inspected all the tires for any damage or sharp objects, none found. So they topped the tire up with nitrogen (the actual reason why I went there) The service rep stated that the TPMS is "very sensitive"; "even pothole could trigger it". Not sure if he meant damage caused by a pothole.

Last night I tried my new BlueDriver OBDII scanner and no TPMS related issues were reported. (The alert was still active) However, I could not see any of the "extended" parameters.(such as transmission oil temp) in the list. Maybe it was finger trouble on my end. As some others have stated transmission oil temperature can be monitored with a ScanGuageII, so it is available on the interface. The BlueDriver is still a cool device though.
 

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The service rep stated that the TPMS is "very sensitive"; "even pothole could trigger it". Not sure if he meant damage caused by a pothole.
No.. not damage from a pothole.. just that a pothole could trigger a false positive. I can believe that, based on my one false positive early after taking delivery. It was apparently triggered during driving on a windy road, with some mixed road surface.

Basically, anything that can trigger the AWD or traction control to react to driving conditions, could cause a false positive on the TPMS. Clearly it does not happen too often or we would have an OD thread sized discussion about it. :)

Heh, so apparently it is allegedly very sensitive to being jostled around in certain conditions, but in terms of tire pressure difference between tires, it appears to not get worked up about it until a tire is 25% below spec PSI. :p I think Honda knows all of this, and that is why the user has a calibration feature. :)
 

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Discussion Starter #11
The initial TPMS calibration on my car was initiated when I drove off the lot. The car had 30km on the ODO with a new set of winter tires and rims. I am now beginning to wonder if there was not some form of bedding in that happened over the first couple of thousand of kilometer that caused the sensor parameters to shift enough to trigger a warning. As I have mentioned. I was driving in a straight line and a constant speed on a smooth asphalt surface when the TMPS warning came on. Anyway. No TPMS related concern at this point. I just love driving the CR-V. It is such a comfortable car.
PS I agree, 25% below spec sounds just too much. Maybe some eager owner can deflate a tire and to see when the TPMS triggers. :cool:
 

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Thanks to all who have responded.

I just came back from the dealer. They hoisted the car and inspected all the tires for any damage or sharp objects, none found. So they topped the tire up with nitrogen (the actual reason why I went there) The service rep stated that the TPMS is "very sensitive"; "even pothole could trigger it". Not sure if he meant damage caused by a pothole.

Last night I tried my new BlueDriver OBDII scanner and no TPMS related issues were reported. (The alert was still active) However, I could not see any of the "extended" parameters.(such as transmission oil temp) in the list. Maybe it was finger trouble on my end. As some others have stated transmission oil temperature can be monitored with a ScanGuageII, so it is available on the interface. The BlueDriver is still a cool device though.
Supposedly the BlueDriver will be adding more functionality over time, so I'm told. I asked them if they were planning to add some bi-directional functions and was told they're "working on it" but not to expect anything in the near future. It's a cool device though lacks a lot of what I can do with my professional scantool, like programming new keys into my anti-theft system, etc. Saved a bunch of money as my remote failed twice on my 2012 and I just swapped out the remote portion with those cheapy ones from Amazon and reprogrammed them into the system. Otherwise, you'd spend almost $200 each at the dealer for a new key and programming.
 

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The initial TPMS calibration on my car was initiated when I drove off the lot. The car had 30km on the ODO with a new set of winter tires and rims. I am now beginning to wonder if there was not some form of bedding in that happened over the first couple of thousand of kilometer that caused the sensor parameters to shift enough to trigger a warning. As I have mentioned. I was driving in a straight line and a constant speed on a smooth asphalt surface when the TMPS warning came on. Anyway. No TPMS related concern at this point. I just love driving the CR-V. It is such a comfortable car.
PS I agree, 25% below spec sounds just too much. Maybe some eager owner can deflate a tire and to see when the TPMS triggers. :cool:
Consider the possibility also of a simple signal glitch that triggered a false positive. Many of these modern vehicles will get a glitch here and there for no apparent reason. Nature of the advanced electronic beasties in these modern vehicles.

As for testing when the TPMS will trigger.... I already have three data points in my home on two different Hondas with the new passive system (2017 CRV, 2018 Accord). All valid TMPS triggers were due to a nail in the tire. On my CRV, one time... set pressure of 33lbs (front tire) and the TPMS popped at 24lbs. I literally could not see by looking at the tire that it was low.. but my pressure gauge confirmed it. On my wifes Accord... twice now, each time a nail.... TPMS when off on the first one when she just got home and I checked the tires and found one at 22lbs (32lbs is spec for the Accord), and the second time, it went off when she was driving home on the freeway, and when I checked it at home, it was 21lbs.

All in all.. and amazingly for a passive system monitoring wheel rotation speeds ... pretty consistent in my experience. And while it seems like low 20s is a bit far for the TPMS to go off, if you think about it.. for a passive system making it tighter will result in a lot more false positives, simply because many people do not check and inflate their tires as regularly as they should. In addition, on both my CRV and the Accord, there were no apparent handling problems before the TPMS went off, and in each case it was difficult or impossible to figure out which tire was low from just visual inspection. So, I think that Honda has it about right from my experience.
 

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FYI , for what it's worth I have had 2 TMPS events in my '17 CRV in 3 years. #1 was while on a 1200 mi. road trip. Came on while I was at my visit location. Went to nearest dealer but could not tell them which tire it was? Dealer went through it and said it was just low pressure/ no charge/ warranty. Drove home 600 mi. and after it was parked for a few days without driving R/R rear tire went flat? Pumped tire up, went to my local shop (much closer than the dealer). Problem found was a small nail in the corner edge of the tread line and pluggable. With respect to the dealer the nail was hard to find as the head was gone and they had 4 tires to deal with an hour before closing time? But what can I say, in the end I didn't get stuck on the road. #2 activation was a 10 mile stretch of rough worn out "washboard" road surface. When I got home I kept eye on the tires over a few days without a low tire problem. Only had to reset TPMS and it reset without doing anything else as I figured it was the road condition in the first place..
 

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Discussion Starter #15
Wow, these are all good info and data points! Thank you Garfy, williamsji and bucch33 for sharing. I now have a pressure gauge in the glovebox. "Cubby-hole" if you are from the Barbados, South Africa, Zimbabwe, parts of southern Minnesota or northwest Wyoming ;)
 
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