Ducato TPMS : Series 10

[Robinhood]

Over recent years there has been some discussion on forums about the TPMS system fitted to the Ducato (and its near cousins) revolving about the fact that pressures have been factory set, with no (easy) way for an end-user to determine/set their own preferred settings.

This has been of particular concern to those users who prefer (rightly or wrongly) to run CP rated tyres at below the high recommended pressures (c80psi) in order to improve ride and retain their fillings. Such practice has been difficult with the factory-set values, as the reduced pressures have often been below the "alarm" threshold, and they need dealer-level diagnostics to adjust (and many dealers have been reluctant to do so).

I've yet to validate the following, but from the owner's manual the Series 10 Ducato appears to have migrated to indirect TPMS (that doesn't rely on actual pressure sensing via valve sensors, but on the signal from the ABS sensors to calculate variation wheel revolution speed resulting from a drop in pressure, and the change in associated circumference). The manual also details the fact that the "reference" value can be reset after adjusting the tyres to the correct/desired pressure. The latter is a fairly logical requirement of the different TPMS method, and would be a great improvement.

It would be interesting to see if all is as the manual describes (as it sometimes isn't in such manuals). 

[Steve928]

That's an interesting development should it turn out to be the case.

I guess I've been lucky because I've not had an issue with Ducato/Boxer direct TPMS across 2 vans, 10 years and around 120k miles; 7-8 year old sensors continue to broadcast correctly and I've yet to see an error condition. The one time I had a loss of pressure (not a puncture but a cracked steel wheel) the TPMS reported it in time for me to exit a very busy northbound A1 and find a quiet place to change the wheel.

Equally the indirect TPMS in my VAG and PSA cars has been good and reported the only puncture correctly in time for me to stop and change the wheel, despite it being major tyre damage.

There are of course plusses and minuses to both systems, for example:

- if you run direct TPMS trigger values close to the actual pressure then it will often raise an alarm following pressure changes due to temperature changes and/or serious descending; alpine cols etc.

- only direct TPMS can report a road wheel's actual pressure and temperature (not easy on the Ducato, but do-able) 

- indirect TPMS often needs resetting upon tyre changes even though the tyres are of ostensibly the same size (not a big deal..)

Personally I'd take direct TPMS every time but then I'm an IT geek and find it interesting.

[Derek Uzzell]

This link provides details of the very latest Ducato (10)

https://www.fiatprofessional.com/uk/ducato/new-ducato/all-in-one

In the CONNECTIVITY/MAINTENANCE section is the following information

The display on the phone seems to show actual tyre-pressure values, which would imply that the TPMS is the 'direct' type.

Evidently this capability is one of the MOPAR CONNECT features

https://www.fiatprofessional.com/uk/mopar/connected-services

My 2024 Skoda Fabia has something similar (called SKODA CONNECT) that allows me to remotely check whether the car is locked, its mileage range, etc. I can remotely lock and unlock the car, flash its headlights and sound its horn, but I am unable to check tyre pressures as the car has 'indirect' TPMS.

The usual 'give-away' between the two types of TPMS is that a vehicle with 'indirect' TPMS will have a Reset button (or menu entry)that needs to be pressed,  whereas a 'direct' TPMS system will not have a Reset capability and will (should!) automatically reset itself once the tyre that has triggered a TPMS warning has been re-inflated to the correct pressure.

[Robinhood]

...extract from the latest (Series 10) Ducato Manual   (there is no documentation of any other type of TPMS therein, and the tyre warning light refers only to iTPMS)).

[Derek Uzzell]

OK, that's clear enough.

My Skoda Fabia's indirect TPMS is reset in a similar manner to that described above, but - if a warning is issued - no information is provided as to which tyre has been recognised as being under-inflated.

I can't see any particular reason why, when an indirect TPMS system identifies an under-inflated tyre (or tyres) via the wheel speed sensors, it would be impossible for a 'smart' system to indicate the wheel(s) involved. However, indirect TPMS systems never seem to do this,

I am unable to get sufficient definition on the image of the phone in Fiat adverts to read what the tyre pressure information is saying. It's possible that all that is being shown is that the TPMS system is (or is not - green tick) identifying an under-inflated tyre and showing the recommended tyre pressures for each wheel.

[Deneb]

My Volvo has indirect TPMS and does indicate which tyre is involved in the event of a fault. Of course the system knows because it alerts when an individual wheel sensor sends information out of sync with the other wheel sensors. Whether Fiat or other manufacturers implement that may be another matter.

Don't place too much reliance on iTPMS systems for timely notification of any faults. According to Volvo, the EU algorithm, which is more stringent than that adopted in other markets, only alerts when a pressure loss of more than 20% has been detected at a single wheel for a period of at least 10 minutes, or for more than one wheel, a pressure reduction of at least 20% + 7kPa over a period of at least 60 minutes.

They are by their very nature and the likelihood of false alerts at increased levels of sensitivity, less precise that direct systems which monitor the actual tyre pressures at each wheel through specific pressure sensors rather than relying on wheel rotational differences observed by the ABS system.

[Steve928]

1 hour ago, Deneb said:

According to Volvo, the EU algorithm, which is more stringent than that adopted in other markets, only alerts when a pressure loss of more than 20% has been detected at a single wheel for a period of at least 10 minutes, or for more than one wheel, a pressure reduction of at least 20% + 7kPa over a period of at least 60 minutes.

The actual text from ECE/TRANS/WP.29/2016/63, as adopted by the EU, is as follows and interestingly doesn't mention '20% + 7kPa' in the case of more than one wheel :

"The TPMS shall illuminate the warning signal described in paragraph 5.5. within not more than ten minutes of cumulative driving time after the in service operating pressure in one of the vehicle's tyres has been reduced by twenty per cent or it is at a minimum pressure of 150 kPa, whatever is higher.
The TPMS shall illuminate the warning signal described in paragraph 5.5. within not more than sixty minutes of cumulative driving time after the in service operating pressure in any of the vehicle's tyres, up to a total of four tyres, has been reduced by twenty per cent or it is at a minimum pressure of 150 kPa, whatever is higher."

Notably the regulation doesn't differentiate between direct and indirect TPMS so an EU type-approved vehicle should leave the production line set to those same values, irrespective of how it determines the reduction in pressure. Of course the beauty of direct TPMS is that you don't need to stick with the EU's 20% and (provided you have the equipment and ability to adjust the trigger values) can set the system to alarm at a percentage reduction of your own choosing.

[Robinhood]

6 hours ago, Derek Uzzell said:

I am unable to get sufficient definition on the image of the phone in Fiat adverts to read what the tyre pressure information is saying. It's possible that all that is being shown is that the TPMS system is (or is not - green tick) identifying an under-inflated tyre and showing the recommended tyre pressures for each wheel.

That screen is a "mock-up" Derek. The Fiat app supports various group vehicles, including cars. The pressure values in that display, which are wildly different to (lower than) those specified for any Ducato variant rather reflects that it isn't real.

[Deneb]

20 minutes ago, Steve928 said:

The actual text from ECE/TRANS/WP.29/2016/63, as adopted by the EU, is as follows and interestingly doesn't mention '20% + 7kPa' in the case of more than one wheel :

Thanks. I took my figures from the functional description in Volvo's diagnostic application, which is obviously not the ECE Regulation.

I have thankfully never suffered a fault, but in the event of an activation the instrument cluster displays an overhead view of either the whole car or front/rear as appropriate, with an amber marker against the affected tyre(s).

When calibrating the system, an overhead view of the car is shown in the infotainment screen, with yellow marks on all four tyres. The calibration progresses as the vehicle is driven until all four indications turn green.

Not a Ducato I know, but I mention it out of interest. They quote longer detection times and at least a 25% reduction in tyre pressure for other markets, and also state that in the US market the detection is calculated against the cold tyre pressure, whereas in the EU it is calculated against the heated pressure. The implementation could of course be a mix of relevant legislation and internal design decisions, as long as the latter complies with the former!

[Derek Uzzell]

16 hours ago, Robinhood said:

That screen is a "mock-up" Derek. The Fiat app supports various group vehicles, including cars. The pressure values in that display, which are wildly different to (lower than) those specified for any Ducato variant rather reflects that it isn't real.

I was aware that an identical phone display appeared on webpages relating to other Fiat vehicles, not just the latest Ducato. But, if 'remote viewing' of a Ducato 10's tyre pressure is possible (as the website says) as the TPMS system is indirect, what information will appear on the phone? As the actual pressure won't be measured, if a tyre is detected as being under-pressure, perhaps the Ducato's system can indicate which tyre is involved, as with Deneb's Volvo.

A few weeks ago, returning from an early morning shopping trip, our 2009 Skoda Roomster's TPMS issued a warning. I use a 32psi pressure for all four of the car's (near-new Falken) tyres and, when we arrived home 5 minutes later, the pressure in the front-left tyre was found to be 22psi and removing the wheel showed a small staple embedded in the tread. Once it was known that there was a problem, it was (just) possible to see which of the four tyres was down on pressure, but the 10psi pressure drop was otherwise not immediately obvious. I suspect that the staple was picked up two days earlier and had then worked its way through the tyre's carcass. Sadly (for my wallet!) the position of the staple right on the edge of the tread where it met the tyre's side-wall meant that the tyre could not be repaired. What did surprise me was that a 30% pressure drop  had been necessary to trigger the TPMS.

[Robinhood]

Of course, all this debate is on the basis of a Fiat manual, the contents of such historically not having been "gospel".

My Volvo (with iTPMS) is also capable of displaying which tyre(s) is/are suspect.

The point I was making about the app display being a mock-up is that, though it is clearly headed "Ducato", the pressures shown as correct/to spec are not suitable for any known version (by a large margin).

That particular bit of the screen layout could well be relevant for other group vehicles. For iTPMS equipped ones it might simply carry a tick or cross (the latter if a warning has previously been invoked, and no reset carried out).

In the s10 manual, the instrumentation part carries wording to the effect that, if the iTPMS system fails (as a whole), a warning graphic of the vehicle will appear with "---" shown against each corner (tyre location). So maybe under normal working the system can determine which tyre(s) are suspect?

Or maybe I've just started a long debate on the basis of flawed documentation 😉.

We'll probably have to wait until someone gets an S10 'van for a definitive answer.

[Steve928]

41 minutes ago, Derek Uzzell said:

A few weeks ago, returning from an early morning shopping trip, our 2009 Skoda Roomster's TPMS issued a warning. I use a 32psi pressure for all four of the car's (near-new Falken) tyres and, when we arrived home 5 minutes later, the pressure in the front-left tyre was found to be 22psi and removing the wheel showed a small staple embedded in the tread. Once it was known that there was a problem, it was (just) possible to see which of the four tyres was down on pressure, but the 10psi pressure drop was otherwise not immediately obvious. I suspect that the staple was picked up two days earlier and had then worked its way through the tyre's carcass. Sadly (for my wallet!) the position of the staple right on the edge of the tread where it met the tyre's side-wall meant that the tyre could not be repaired. What did surprise me was that a 30% pressure drop  had been necessary to trigger the TPMS.

I suppose it could it have been the case that the tyre's pressure dropped from 25.8 p.s.i (20% loss) to 22 p.s.i. (over 30% loss) within the 10 minutes of 'cumulative driving time' that the TPMS can wait after breaching the 20% threshold before triggering an alert, finally triggerring the alert at the point that the 150kPa minimum pressure was reached.

Edited November 27 by Steve928

[Derek Uzzell]

After I had removed the wheel with the punctured tyre and fitted the spare wheel, I re-inflated the punctured tyre to 32psi and stored it in the car's boot. 24 hours later, the punctured tyre's pressure had dropped to around 20psi.

I'm guessing I picked up the staple on a visit to the local recycling centre 2 days before as the car had not been driven since then until the shopping trip. I had checked the air leakage when I took the wheel off and it was very slow. I saw the inside of the tyre after it had been removed and just one of the staple's prongs had penetrated right through the carcass (I'd easily pulled out the other prong). It was just bad luck that the staple had gone in where it did.