Tyre Pressure.

[Hans]

Does any one on the forum is informed how it works when connected to ABS.? When the light goes on at the dash?

[rayc]

Hans - 2020-09-08 7:31 PM

 

Does any one on the forum is informed how it works when connected to ABS.? When the light goes on at the dash?

 

The ABS is triggered by sensing the speed of the wheels. If a tyre has low pressure it can cause the ABS to trigger as its speed of rotation will not be the same as the remaining wheels. There is no connection between the TPMS and the ABS.

[Keithl]

Hans,

 

As you imply there are two very different methods for TPMS to operate.

 

The first has a transmitter inside each wheel and a receiver or aerial nearby to receive the signal which is then relayed to the dash display.

 

The second utilises the individual wheel speed information, taken directly from the ABS as you say. If one wheel is rotating at a different speed to the others, under specific conditions and tolerances, the dash display will alert the driver.

If you fit different size tyres to standard, run at none standard pressures or possibly even overload one axle there is a very high risk of a false alarm.

 

Keith.

[Hans]

Thanks rayc. Is this correct: I had a trigger My wife Monique said on bad soil yesterday who activate the tyre pressure light. But tyre pressures were correct. TPMS is real pressure. I do not have TPMS and was not even Aware i had a warning via the ABS sensors. Anyway it is warning to look at your tyres. The ABS has a RESET button in the Glove Box.

[Steve928]

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Keithl - 2020-09-08 8:38 PM

 

The first has a transmitter inside each wheel and a receiver or aerial nearby to receive the signal which is then relayed to the dash display.

 

Keith.

 

For info. on the X290 there is only one receiver (located above the rear of the front sub-frame as pictured) as opposed to individual receivers near each wheel.. The individual wheel sensor positions are then determined using WAL (Wireless Auto-Locate) which is based upon RF signal strength.

[Hans]

Thanks Keithl.

 

[Hans]

Steve nice capture picture. If looking front is it left or right. Is LHD Or RHD different? Huge questions coming from the club.

[Derek Uzzell]

As Keith has said, there are basically two types of TPMS - indirect (exploiting a vehicle’s ABS/ESC wheel sensors) or direct (using a battery-powered sensor fitted to the tyre valve). The two systems are described in more detail on these links

 

https://en.wikipedia.org/wiki/Tire-pressure_monitoring_system

 

https://www.johndow.com/two-types-of-tpms-systems/

 

The VW Group has historically fitted an indirect TPMS system to its vehicles. My Skoda car has this and there’s driver-operated press-button on the centre console that allows the system’s comparative wheel-speed parameters to be reset if (say) a new tyre were to be fitted. Although using the button affects the car’s TPMS systen, it has absolutely no effect on the ABS/ESC system itself.

 

When a Citroen Relay/Fiat Ducato or Peugeot Boxer has a factory-fitted TPMS system, that system is the direct type. The road wheels have tyre valves with a battery-powered pressure sensor on the valve’s base (ie. beneath the underside of the wheel rim) as shown in the attached example.

 

This type of system will have its pressure settings input when the vehicle is built and (normally) will NOT allow a driver to easily alter those settings. (There have been plenty of motorhome forum complaints about this - mainly relating to Peugeot Boxers - where owners have wished to reduce the high tyre pressures advised when ‘camping-car’ tyres have been factory-fitted.)

[Steve928]

Hans - 2020-09-08 9:30 PM

 

Steve nice capture picture. If looking front is it left or right. Is LHD Or RHD different? Huge questions coming from the club.

 

The picture depicts a LHD vehicle - you can see the steering column end of the steering rack - which should mean that the TPMS receiver is off-centre towards the left hand side of the vehicle (which would give different distances to all four TPMS valves, to allow WAL to function).

I'd expect it to be in the same place on RHD vehicles but I must admit that I haven't looked.

 

Here's a picture looking from the rear of the vehicle.

[Steve928]

Derek Uzzell - 2020-09-09 9:13 AM

 

This type of system will have its pressure settings input when the vehicle is built and (normally) will NOT allow a driver to easily alter those settings. (There have been plenty of motorhome forum complaints about this - mainly relating to Peugeot Boxers - where owners have wished to reduce the high tyre pressures advised when ‘camping-car’ tyres have been factory-fitted.)

 

I've now re-programmed the TPMS on both my previous Boxer and the current Ducato and although it's straightforward the kit isn't particularly cheap, although probably less in cost terms than an hours labour at a main dealer.

 

For Boxers and Relays a VMWare virtual machine image of the Diagbox software can be downloaded off of the web. Chinese clones of the Actia A.1281Z interface module and the S.1279 converter for Italian vehicles (which multiplexes the high and low speed CAN buses) can be had on Ebay. My Chinese S.1279 module didn't work but luckily it's a common problem and there are clear instructions on the web covering how to modify it.

 

For the Ducato I purchased the Multiecuscan package from Zendan which, although not the cheapest solution, is guaranteed to work as it doesn't use the cheaper ELM327 cable but uses a proven but much more expensive OBDlink SX cable instead. To switch between high and low speed CAN buses the software prompts you to insert or remove an additional cable that simply swaps some connections about.

 

In addition to the above AlfaOBD (which costs about the same as Multiecuscan) is reputed to work with the TPMS ECU on both PSA and Fiat vehicles, using the same cables as Multiecuscan. While Multiecuscan checks the ECU's ISO code, which differs between manufacturers, AlfaOBD doesn't (or so I've read, but not tried..) so will program what is after all the same TPMS ECU on both marques.

[Derek Uzzell]

I did say“easily alter”... ;-)

 

The underlying drawback of the TPMS system fitted to certain recent-ish coachbuilt motorhomes that are Peugeot Boxer-based is that many buyers of such vehicles have, in the past, been accustomed to reduce the high tyre pressures (70psi to 80psi) that are normally prescribed by Peugeot and/or the motorhome converter to significantly lower pressures having sought advice from the manufacturer of the tyres. Having reduced the pressures, the buyers then find that their motorhome’s TPMS system starts to issue warnings, that the TPMS system is not intended for ‘owner adjustment’, and that Peugeot dealerships will generally refuse to reset theTPMS system’s pressure settings according to a buyer’s wishes.

 

Plainly (as you’ve said) if a motorhome owner has the appropriate kit and the necessary expertise, it’s possible to alter the TPMS tyre pressure parameters, but there will be very few owners who willl be prepared to go down that route even if they have the skills. I believe the latest Ducato generation has the same TPMS system as standard, so it’s going to be interesting to see what happens...

 

This 2016 forum thread discussed the ‘joys’ of the TPMS system of your Boxer-based Bailey motorhome

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/More-TPMS-fun-games/43610/

[Steve928]

Derek Uzzell - 2020-09-09 1:42 PM

 

I did say“easily alter”... ;-)

 

Indeed - sorry, it wasn't meant to contradict what you were saying, rather just to add some information for those DIY owners who might like to explore the options.

[Deneb]

I don't know whether AlfaOBD checks the ISO codes of the ECUs it is connecting to or not, but I would be surprised if it didn't carry out specific checks as allowing programming attempts with an incompatible unit could result in serious issues.

 

The AlfaOBD developer has however made a conscious decision to support the Peugeot and Citroen variants of Sevel vans in his application, including specific ECUs on certain derivatives of those vehicles which are not shared with the Fiat versions, such as for the different engines.

 

MultiEcuScan is intended for FCA vehicles only, so the fact that the other manufacturers variants aren't supported is also a deliberate decision by the author of that program.

 

[goldi]

Good morning,

 

Things are getting really complicated now with camping

[Derek Uzzell]

Here’s the solution.

[Driventemple]

I too was finding the tyre pressures as set on my X290 too high for comfort. I purchased the Multicuscan software and appropriate connections then reset the fronts to trigger at 4000. I now run these fronts at 65psi and find the ride much better.

[Derek Uzzell]

Being an Apple-only user (iMac, IPad, iPhone) I’ve nothing suitable for running the Multiecuscan software on (and I can’t justify buying a cheap Windows laptop specifically for the purpose).

 

However, reducing my Rapido’s recommended tyre pressures (215/70 R15CP Michelin "Agilis Camping” tyres) from the advised 5.0bar (front) and 5.5bar (rear) to 4.5bar (F) and 5.0bar® did result in a noticeable improvement to the motorhome’s ride quality on rough roads and addressed the over-lightness (in my view) of the steering when the recommended higher pressures were employed.

[Deneb]

I thought Mac's could run a Windows emulator Derek? It doesn' t have to be powerful. I run MES on an old Windows 7 netbook, but I also have it running on an XP virtual machine on my desktop PC.

[Derek Uzzell]

Yes, that's possible

 

http://forum.multiecuscan.net/viewtopic.php?t=5902

 

and a version of MES is offered on the APP Store (with poor reviews).

 

However, I can't see me connecting my elderly (and hefty) iMac desktop to the Rapido.

 

I might have found some use for MES earlier this year when I provoked a batch of fault codes, but these all 'self-corrected' except for one that was cleared when the motorhome was serviced.

 

 

 

[Hans]

Derek it not wise to try to alter the software related to safety. Tyre pressure is one of them. Software was all around in our house for years .Look at the Boeing MAX what can happen. my VW dealer also reduced the pressure for comfort. And ABs sensors have no problem whit that. Back in the High Life Again for some time. Cheers.

[Steve928]

Deneb - 2020-09-09 5:16 PM

 

The AlfaOBD developer has however made a conscious decision to support the Peugeot and Citroen variants of Sevel vans in his application, including specific ECUs on certain derivatives of those vehicles which are not shared with the Fiat versions, such as for the different engines.

 

 

I was wondering if you had come across anyone who has used AlfaOBD on Peugeot/Citroen successfully, Deneb?

I downloaded both the PC and Android demo versions and there are some glaring errors in the modules selectable under Peugeot e.g. selecting 'Engine' brings up exactly the same list of engines/ECUs as for the Ducato including the 2.3 (never fitted to PSA) and the current BlueHDi units are not listed.

I suggested to my old friends on the Bailey Facebook group that they give it a try but they are reporting failure to connect to any modules on the Peugeot cabs.

It could of course be a problem with their chosen interfaces but I'm suspicious that perhaps PSA functionality in AlfaOBD is a work in progress.

[Deneb]

I haven't to be honest. The only observation I can make is that it does seem to require a decent OBD dongle such as the OBDlink MX or OBDkey devices recommended by the developer. I originally tried using a couple of cheap ELM devices that I'd already got and used successfully with other software, but couldn't connect to several ECUs on my Ducato. Everything works fine with OBDkey though, but OBDkey doesn't work well with my Volvo, yet the cheap ELM dongles are fine!