Yellow tyre pressure warning.

[AlexS]

Specific question. Is it possible to detect or show which tyres are detected as deflated according to the sensor after the yellow deflation warning light comes on? If so how?

I appreciate I can measure tyre pressure via the usual methods.

Thanks

Alex

[TnTkr]

No it isn't. Basically the system detects that there is difference (above set tolerances) in wheel rotating speeds calculated as average on certain time and measured from abs-sensors on each wheel. I doesn't give any additional information which wheel speed is causing the warning.

[Jocko]

The Jazz system doesn't measure tyre pressures, it only measures the difference in the rotation rate of wheels, so unfortunately no, you have to check which tyre is deflated.

[Jocko]

As TnTkr stated before me. 

[ColinB]

The Jazz system ... only measures the difference in the rotation rate of wheels, ...

I suspect it doesn't even do that. If it monitored individual wheel speed differences, it would be able to indicate which wheel was deflating. But that requires monitoring four parameters (one for each wheel). The efficient way to design the system would be to have the computer calculate a single checksum from all four wheel speeds and sound the alarm if that checksum value was outside the values calculated during the calibration. That monitors just one parameter, and would indicate there was a problem but couldn't tell you where the problem was ... which is exactly what happens.

[TnTkr]

That sounds feasible. However, I haven't done any recalibration after seasonal tyre changes, and I have different size and different rolling circumference in summer and winter tyres. So if there is single checksum, then the tolerance must be quite wide.

[jazzaro]

That sounds feasible. However, I haven't done any recalibration after seasonal tyre changes, and I have different size and different rolling circumference in summer and winter tyres. So if there is single checksum, then the tolerance must be quite wide.

Same for me if I keep the exact position (tires that were in front position placed again in front), I must recalibrate if I change front position with rear.

[TnTkr]

I even rotate tyres, but that way the tread depth remains pretty equal.

[richardfrost]

My Toyota RAV4 has pressure sensing valves on all the wheels and still doesn’t tell me which one has dropped. To be honest, it doesn’t matter. It’s good practice to check them all anyway. Last time I had an alert, three tyres needed air. Back in 2003 I got a Renault Laguna top of the range and that could tell you which tyre was low. The graphic used to show the car with a wheel missing. It was very prone to false alarms and every time it showed us that graphic we’d all sing “Three wheels on my wagon”. I’m

[Lord Voltermore]

When I changed from 185/55/R16  summer wheels to 185/60/R15  (on all seasons)  and took care that the tyre pressures were the same as before,  the system didnt notice the difference.

 Although one set may have rotated faster or slower than before at any given road speed  the system 'assumed' it was just a change in road speed. All 4 tyres still rotated at the same relative speed to each other.  Same happens if you adjust tyre pressures. If you adjust them all by exactly the same amount   the system wont need to relearn the settings. 
 
   The system did trigger after about 200 miles  but this was because the brand new tyres had bedded in.  The same happened when the car was brand new on original tyres.     A quick relearn and no problem since.

I dont see it as a  problem that you dont know which tyre (if any) has lost pressure or been over inflated.  I would want to take the opportunity anyway to check the pressures are ok on all 4.
     The Honda indirect system has the advantage that you dont need to buy or periodically replace  expensive monitor valves ,if for instance its transmitter battery runs low. 

[Downsizer]

I’ve always assumed the system compares the rotation of the two front tyres, and separately compares the two rears, as front and rear tyres generally have different pressures. Either way, it only takes a few minutes to check all four by hand to find the culprit.

[jazzaro]

I’ve always assumed the system compares the rotation of the two front tyres, and separately compares the two rears, as front and rear tyres generally have different pressures. Either way, it only takes a few minutes to check all four by hand to find the culprit.

No, the system compares the rotation of all tyres; when you reset the system, the ecu in some kilometers will "learn" how all tires rotate and the slight difference that every wheel could have, then the ecu will check if one or two wheels increase this difference.
The yellow warning on our Jazz does not mean "check that specific tyre because it could be punctured", it means "check your tires because one or more of them could be not ok".

[AlexS]

Thanks for your help folks!

[Lord Voltermore]

 The system learns what is normal wheel rotation and triggers if any tyre changes compared to the other three.  It doesnt matter what pressure each tyre is at when it learns its rotation speed compared to the others.  Its a change in any one tyre that matters.    This also allows for the fact that tyre pressures will go up as tyres warm up, or up and down depending on ambient  air temperature.   Crucially they will all change by about the same amount  so they still rotate  the same  compared to the others.  Unless a tyre fault does indeed cause one  to overheat more than the others. 

I think the system can also allow for the fact that  when cornering  each  wheel may follow  a different  arc to the others ,slightly altering relative rotation speeds. (the outer wheel has further to travel than the inner so has to rotate faster) )      I think it takes an average over a period rather than immediately triggering  to any change.   

[jazzaro]

The system learns what is normal wheel rotation and triggers if any tyre changes compared to the other three.

or if any couple of tires changes compared to the other couple. The trigger is the change.

It doesnt matter what pressure each tyre is at when it learns its rotation speed compared to the others.  Its a change in any one tyre that matters.    This also allows for the fact that tyre pressures will go up as tyres warm up, or up and down depending on ambient  air temperature.   Crucially they will all change by about the same amount  so they still rotate  the same  compared to the others.  Unless a tyre fault does indeed cause one  to overheat more than the others. 

Correct!

I think the system can also allow for the fact that  when cornering  each  wheel may follow  a different  arc to the others ,slightly altering relative rotation speeds. (the outer wheel has further to travel than the inner so has to rotate faster) )      I think it takes an average over a period rather than immediately triggering  to any change.

All car's ECU are connected each other using a CAN-BUS network, so the ABS/ESP ECU (in our case the ECU performing the TPMS service) knows if the car is steering or if it's driving straight because the Electric Power Steering ECU shares the instant steer angle value to all other ECU such as ABS and NAVI. The system knows also HOW MUCH the car is steering and how much every wheel should rotate when you are curving, the front-external will be the fastest and the rear-internal the slowest, so the TPMS can detect a puncture also when the car drives on a long and slight curve.