So TPMS learnings this week - Playing with Autel MX Sensors for TPMS and the second set of wheels/tyres.
I got to the bottom of my crossed over views from my last post above ... the Right Front and Right Rear were recorded wrong on the Grenadier OBD versus their actual location (this was as the Dealer had delivered that car - they have learned their mistakes too which you can read below).
Now I have my new wheels on, I started with wheels with Autel MX sensors automatically activated to some random code generic codes (not the codes from my old wheels) and I went through each wheel in turn and cloned the old wheel sensor code on to the new wheel Autel MX sensor and then read the sensor (with the Grenadier Ignition on) and then checked the screen. I used the fact that my pressures differed from previous reading by enough to trigger the warning screen as well so I could have both. And correlate where Grenadier through each wheel was an straight off it got confused with the right rear and put it in two places (and on one view neither was the Right Rear which is still showing blank)
Wheels RR and LF done (RR is showing up in multiple locations - this is the indication of in the wrong place on the Grenadier OBD versus the actual Tyre location) - This was a deliberate choice - I stayed clear of the locations where there was ambiguity (which was everywhere but the LF wheel) and in the two views I have the tyre in 3 different locations:
To help with my process these were important steps:
1) I set all tyres to be slightly different pressures (by at least 4kPa) and went through checking.
2) I set the units to kPa on my Autel MaxiTPMS TS508 and on the Grenadier (cause its more sensitive and then I didn't have to change the tyres by as much as the Grenadier doesn't show psi with decimal places) ... note that Autel and Grenadier may differ by up to 3kPa as their maths for conversion must be slightly different (and the sensor will hand out a reading converted by the software to the unit of choice). So within 3kPa it is the same tyre, and I note the temp seems to agree between both Grenadier and my TPMS tool (And also there is a fraction of time difference between the two measurements as I can't be in two places at once) .
3) I also set the Autel TS508 to be able to program ignoring that the sensor has pressure allowing me to recode the inflated wheel sensors (this is a safety feature on a Autel unit set by default to stop you inadvertently wiping out the wrong tyre when doing sets of wheels, where once the wheel is inflated to above 8psi the programming of the sensor is blocked by the tool).
Result back at delivered location settings (with the new wheels) but not matching physical placement: And I can see that two wheels are swapped RR & RF (versus my TPMS tool measure round the car) - I used the kPa as the Grenadier view doesn't show the TPMS ID
I recognised the issue of the wheel swap and recoded the sensors to the match what the OBD i trying to show (rather than swapping the newly mounted wheels) and all is good with the world. All 4 tyres correct and with a simple cold pressure reset, the warning screen will go away.
@MossyIG suggests that 75F is the limit at which you can't perform a cold reset (well my tyres started today at 24C and I was able to do the cold reset at the end) - I can't find the value documented anywhere through. And later I can do a successful reset with a tyre at 39C 103F)
Final result (after a short drive as the cold reset doesn't show immediately): (I could also have trigger the sensors with the TPMS tool I suspect... and the pressures have change due to the drive so I now have two same kPa but different temp so can still tell them apart)
I do note though that it is not a high enough threshold for an on-road pressure change and its low enough also that some days on my last road trip a cold tyre reset at the beginning of the day didn't work either.... still a bit to work out here:
Discussion with one of the techs at Ignition Car Center gave me some insight on TPMS relearn from their end today.
- Its actually easy, if you know the trick - you must start with the Right Hand Front Wheel and work around finishing with the spare (99% of TPMS ops starts with the LF not RF wheel). And the Grenadier does hold the spare tyre too in its learn procedure... so I am going to test whether it uses that info or not.
- Note: The Grenadier will NOT self relearn from a swap of wheels (fronts to backs) - you need to use the Ineos Test Tool and do the TPMS Relearn procedure (or if you are liked me with an Autel TPMS tool and Autel Sensors that can be reprogrammed note all the tyre sensor IDs down and put the sensor IDs back to the right place after a wheel swap)
So talking my new learnings, I will do some new tests:
1) SPARE test My next test will be "put the spare on to one of the drive wheels and the drive wheel to the spare) - using Autel MX Magic rather than physical tyre/wheel changes
2) Find the cold relearn limit (I will test by leaving the vehicle out in the sun and checking the cold rest option until I can confirm the upper limit in Celcius where it stops.
Number 2) test today thinking why not after my short drive- I managed a tyre cold pressure reset today at 39C (when I took the final photo above - front right was 39C) (so perhaps my answer to pressures is to do the cold reset a little higher than cold but not too high to not work) - ambient had got up to 29 degrees on my driveway so that maybe outside temp might play into it too for the cold pressure rest op... hmmm
And lastly I would like to gather data on the issue because under Australian drive conditions towing on summer days I can't stay within the magic TPMS variation so I get alerted to death on the trip by the TPMS every 20-30s or so flashing up on the main screen (this with with the OEM KO2 tyres at full vehicle GVM at max recommended pressures). I'll see whether the Yokohama GO16 LT285/70R17s are any different on my next tow outing on freeways ~ 90-95kmh.
So questions out to anyone: For the rear tyres - are you running in to TPMS alerts?
| Tyre manufacture & size | Rear axle weight / total vehicle weight (including towball weight) | Rear Cold Pressure | Alerts (max observed) |
|---|
| KO2 LT265/70R17 | 2000 / 3550 (incl 200 towball) | ~340kPA cold (I inflated to 50psi which is a shade over 340) | 410kPA high pressure alerts (Amber) max temp at 57 (but green still) |
| | | |
