tyre pressure monitors
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Thread: tyre pressure monitors

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    Default tyre pressure monitors

    On my 2009 c5 x7 comfort the service light comes on after driving for about 30 minutes to say tyre pressures are not being monitored. How can i install monitors on to the wheels ??

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    1000+ Posts Kim Luck's Avatar
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    Quote Originally Posted by cee5 View Post
    On my 2009 c5 x7 comfort the service light comes on after driving for about 30 minutes to say tyre pressures are not being monitored. How can i install monitors on to the wheels ??
    Certainly not without some expense! If the vehicle was originally fitted with a set, they are usually coded per wheel location. A set of genuines will costalotta. After-market units can be fitted to any vehicle but can come as a $1k plus set, and won't work with your built-in system, having their own reader.
    Don't it always seem to go that you don't know what you've got 'til it's gone............

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    1000+ Posts robmac's Avatar
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    FWIW some manufacturers, who shall remain nameless, sense tyre pressure without the bs add on pressure sensors.

    indirect TPMS
    Indirect TPMS do not use physical pressure sensors but measure air pressures by monitoring individual wheel rotational speeds and other signals available outside of the tire itself. First generation iTPMS systems are based on the principle that under-inflated tires have a slightly smaller diameter (and hence higher angular velocity) than a correctly inflated one. These differences are measurable through the wheel speed sensors of ABS/ESC systems. Second generation iTPMS can also detect simultaneous under-inflation in up to all four tires using spectrum analysis of individual wheels, which can be realized in software using advanced signal processing techniques. The spectrum analysis is based on the principle that certain eigenforms and frequencies of the tire/wheel assembly are highly sensitive to the inflation pressure. These oscillations can hence be monitored through advanced signal processing of the wheel speed signals. Current[when?] iTPMS consist of software modules being integrated into the ABS/ESC units.
    iTPMS cannot measure or display absolute pressure values, they are relative by nature and have to be reset by the driver once the tires are checked and all pressures adjusted correctly. The reset is normally done either by a physical button or in a menu of the on-board computer. iTPMS are, compared to dTPMS, more sensitive to the influences of different tires and external influences like road surfaces and driving speed or style. The reset procedure, followed by an automatic learning phase of typically 20 to 60 minutes of driving under which the iTPMS learns and stores the reference parameters before it becomes fully active, cancels out many, but not all of these. As iTPMS do not involve any additional hardware, spare parts, electronic or toxic waste as well as service whatsoever (beyond the regular reset), they are regarded as easy to handle and very customer friendly
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    1000+ Posts Kim Luck's Avatar
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    Quote Originally Posted by robmac View Post
    FWIW some manufacturers, who shall remain nameless, sense tyre pressure without the bs add on pressure sensors.

    indirect TPMS
    Indirect TPMS do not use physical pressure sensors but measure air pressures by monitoring individual wheel rotational speeds and other signals available outside of the tire itself. First generation iTPMS systems are based on the principle that under-inflated tires have a slightly smaller diameter (and hence higher angular velocity) than a correctly inflated one. These differences are measurable through the wheel speed sensors of ABS/ESC systems. Second generation iTPMS can also detect simultaneous under-inflation in up to all four tires using spectrum analysis of individual wheels, which can be realized in software using advanced signal processing techniques. The spectrum analysis is based on the principle that certain eigenforms and frequencies of the tire/wheel assembly are highly sensitive to the inflation pressure. These oscillations can hence be monitored through advanced signal processing of the wheel speed signals. Current[when?] iTPMS consist of software modules being integrated into the ABS/ESC units.
    iTPMS cannot measure or display absolute pressure values, they are relative by nature and have to be reset by the driver once the tires are checked and all pressures adjusted correctly. The reset is normally done either by a physical button or in a menu of the on-board computer. iTPMS are, compared to dTPMS, more sensitive to the influences of different tires and external influences like road surfaces and driving speed or style. The reset procedure, followed by an automatic learning phase of typically 20 to 60 minutes of driving under which the iTPMS learns and stores the reference parameters before it becomes fully active, cancels out many, but not all of these. As iTPMS do not involve any additional hardware, spare parts, electronic or toxic waste as well as service whatsoever (beyond the regular reset), they are regarded as easy to handle and very customer friendly
    So, what this fancy system you describe basically does is give you the same information you can obtain from a walk around your vehicle; i.e; Yup none of them are flat!

    "iTPMS cannot measure or display absolute pressure values". Not much chop if you are running 16 PSI in sand.....but I guess you don't need that information on an autobahn....
    Don't it always seem to go that you don't know what you've got 'til it's gone............

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    So how does iTPMS tell the difference between a deflating tyre (which has a smaller diameter) and a worn tyre (which has a smaller diameter)? It seems that it is making a whole lot of guesses to arrive at a result that is way dodgier than that given by in-tyre pressure sensors.
    Stephen
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    '16 Renault Master

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    Quote Originally Posted by cee5 View Post
    On my 2009 c5 x7 comfort the service light comes on after driving for about 30 minutes to say tyre pressures are not being monitored. How can i install monitors on to the wheels ??
    I'm guessing you have changed to aftermarket wheels so you don't have any sensors installed now. Or you have changed to a spare and that one is now not monitored. Do you have a wheel display that shows all 4 wheels?

    I've seen on flea bay you can buy spare transponders but you need to match them via Lexia.

    Sent from my GT-I9195T using aussiefrogs mobile app

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    Easy, off to ebay pay less than $100.

    Unscrew dust cap, screw on the sensor

    Display shows which one is going flat

    Also shows temperature and actual pressure in tyre

    Wireless Car TPMS Tire Tyre Pressure Monitoring System LCD + 4 External Sensors | eBay

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    C5 devices look like this - tyre pressure monitors-tyre-pressure-sensor.jpg
    Each is coded to a wheel, and the BSI stores the info.

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    Quote Originally Posted by Kim Luck View Post
    So, what this fancy system you describe basically does is give you the same information you can obtain from a walk around your vehicle; i.e; Yup none of them are flat!
    [/COLOR]
    About the same data that a "walk around" shows with an absolute pressure measurement system too.


    Quote Originally Posted by Kim Luck View Post
    "iTPMS cannot measure or display absolute pressure values". Not much chop if you are running 16 PSI in sand.....but I guess you don't need that information on an autobahn....
    I would imagine the tyre diameter would be reduced, at 16psi inflation on both sand or on the autobahn. So presumably iTpms would detect an issue.

    And FWIW absolute tyre pressures is not important. Being alerted to a potential issues with the tyres is quite sufficient.

    Just like a humble oil light, the pressure is not the key factor. They fact that the pressure is low is the purpose of the warning.

    And both monitoring systems comply with the European requirements. However one is inherently less complex and therefore more reliable.
    Last edited by robmac; 28th February 2017 at 04:22 PM.

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    The C5 ABS system also reports tyre inappropriate rpm problems (ie diameter) - usually because one has reduced pressure.

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    1000+ Posts Ken W's Avatar
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    You can swop the wheels around on an X7 without any tyre pressure sensor issues. But put a steel spare on and it will bong at you that it can't monitor that wheel position. It also monitors wheel rotation, air temp and its sender battery condition. The sensor will only transmit when the car is moving or if the tyre is inflated to some ridiculous pressure.

    I solved the spare tyre problem by buying a mag off a wreck with a sensor and then logging the sensor MAC address into the tyre ECU with a LEXIA. You need to convert the decimal number on the sensor to a hexadecimal number to enter into the ECU via Lexia. Diagbox may do this better. So now I can put a spare tyre on and not get any messages on the dash. The Tyre ECU has space for about 10 different wheels so you can have a set of summer and winter tyres.

    Cheers, Ken W
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    Hi Cee5,

    Need to start at the beginning.......You car is obviously fitted with a factory tyre pressure monitor system, so the replies about aftermarket sensors need to be disregarded.

    If you not sure if they are factory fitted (it has to be if its coming up in the dash), give me the last 8 digits of you vin & I'll look up your cars specifications on Citroen Service? Or you can do it yourself if you are registered.

    There is obviously something going wrong with the system, and probably not at the wheel end if its not being specific.

    I think that you probably need Diagbox, and do a global test, and see what's happening under tyre pressure monitoring.

    It will come up with a fault code, which will be a start?

    Best regards,

    Greg
    We Have:
    C5 HDI Exclusive 2.7 '09, Pluriel '09, Berlingo 1.6 HDI '10, C4 VTS coupe. C4 Picasso '08, 2CV Charleston '84 Grey, 2CV, '55 Australian delivered. 15/6 H '55, SM '74 BVM, DS21 EFI BVH, DS21 '67 BVH.
    We Had:
    1930C6F, '73 GS1220 wagon X 2, '75 G special, '75 GS panel van, '74 GS Birotor, '82 GSA panel van with factory AC, '85 CX25GTI BVM, 2002 C5 V6, 2006, C5 S2 HDI, '86 BX19GT, '72 DS21 BVM, '55 15/6H, '54 Lt 15,'73 Dyane, '82 Visa Super X, with Chrono Mecs & factory AC, 1972 SM.

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    BTW,

    There is an under inflation receiver, that receives the signal from the sensors..... This may be what's your problem, but again, you'll need diagbox.

    Greg
    We Have:
    C5 HDI Exclusive 2.7 '09, Pluriel '09, Berlingo 1.6 HDI '10, C4 VTS coupe. C4 Picasso '08, 2CV Charleston '84 Grey, 2CV, '55 Australian delivered. 15/6 H '55, SM '74 BVM, DS21 EFI BVH, DS21 '67 BVH.
    We Had:
    1930C6F, '73 GS1220 wagon X 2, '75 G special, '75 GS panel van, '74 GS Birotor, '82 GSA panel van with factory AC, '85 CX25GTI BVM, 2002 C5 V6, 2006, C5 S2 HDI, '86 BX19GT, '72 DS21 BVM, '55 15/6H, '54 Lt 15,'73 Dyane, '82 Visa Super X, with Chrono Mecs & factory AC, 1972 SM.

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    You guys should also be aware that it is (well certainly was) possible to buy the threaded metal neck as a separate part to the sensor. So, if the neck was damaged, the very expensive sensor could be reclaimed. Check the parts listings.

    Plenty of cars had wheel swaps at dealers depending on whether the buyer did/didn't want the larger rims sizes, so what is supposedly on the car is not necessarily what it has fitted. Some cars may also have gained or lost sensors, depending on the wheel swap performed.

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