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Thread: TPMS activation, reset, and disable coding with VCDS - mk6 VW

  1. #11
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    Quote Originally Posted by PetrolDave View Post
    I think you're misunderstanding how indirect TPMS works - it doesn't have pressure sensors so it cannot measure/store any pressure values.

    It measures the rotational speed of each wheel using the ABS sensors, and with some weird software compares that, with tolerances, against values of rotational speed for each wheel that get stored after you use the TPMS reset button/menu.

    When you change wheel sizes or pressures all you have to do is set all the tyres to the correct pressures and reset TPMS. Since you can't see the pressures (as they're not measured) if you're unsure of the set values being used by indirect TPMS then just assume they're wrong and reset TPMS yourself when you know the pressures ARE correct.
    Thanks for the reply PetrolDave. That makes complete sense, unlike what I was thinking. I knew it measured rotational speed (especially differences between tires) but had believed wrongly that it then used that data to calculate (estimate) a corresponding pressure to match to a stored value. I was too hung up on the word PRESSURE in tire pressure monitor system.

  2. #12
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    What does the "Tire Pressure Monitoring (TPMS - PR-7K3/7K4/7K5) Installed/active" bit enable/disable exactly?

    I ask because it's OFF in my 2012 Tig with direct TPMS, but it seems to be working just fine.
    MFD has a Tyre Pressure menu in settings, and working pressure monitoring screen.

    What am I missing, if anything, by having it OFF?

    My full scan is here (on forum).
    These are probably the most relevant bits:
    Code:
    Address 09: Cent. Elect. (J519)       Labels:. 1K0-937-08x-09.clb
       Part No SW: 5K0 937 086 M    HW: 5K0 937 086 M
       Component: BCM PQ35 M    021 0064  
       Revision: BC021001    
       Coding: 40180A3B88251AC0408800C8340011644B550008776D8DF0E4800000A048
       Shop #: WSC 01357 011 00200
       VCID: 3E253EA490712777F85-806A
    
    Address 17: Instruments (J285)       Labels:| 5K0-920-xxx-17.clb-SRI1
       Part No SW: 5N0 920 882 B    HW: 5N0 920 882 B
       Component: KOMBI         H04 0417  
       Serial number: 00000000000000
       Coding: 111F01
       Shop #: WSC 00117 211 00000
       ASAM Dataset: EV_Kombi_UDS_VDD_RM09 A04114
       ROD: EV_Kombi_UDS_VDD_RM09_004_VW32.rod
       VCID: 323D1A9454A9F3170CD-8066
    
    Address 65: Tire Pressure (J502)       Labels: 3AA-907-273.clb
       Part No SW: 3AA 907 273 D    HW: 3AA 907 273 D
       Component: RDKBERU30     H09 0010  
       Serial number: 10000000107439
       ASAM Dataset: EV_RDKBERU30 003012
       ROD: EV_RDKBERU30_003.rod
       VCID: 35372188A5C7E42F29F-8060
    TIA,
    Mark.
    Last edited by markdv77; 10-19-2019 at 09:24 AM. Reason: Bad code tags.

  3. #13
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by markdv77 View Post
    What does the "Tire Pressure Monitoring (TPMS - PR-7K3/7K4/7K5) Installed/active" bit enable/disable exactly?

    I ask because it's OFF in my 2012 Tig with direct TPMS, but it seems to be working just fine.
    MFD has a Tyre Pressure menu in settings, and working pressure monitoring screen.

    What am I missing, if anything, by having it OFF?
    You're not missing anything. You have a direct system that uses actual pressure sensors in the wheels.

    The rest of this thread is about an indirect system that uses some insane amount of signal processing of the pulses from the wheel speed sensors instead of actual pressure sensors.

    There are benefits and drawbacks to both approaches. A direct system can show you actual pressures, but requires additional hardware (i.e. it adds cost to the vehicle when new) and some of that hardware (the sensors) will surely have to be replaced at least once during the lifetime of the vehicle.

    An indirect system is really just software in the ABS module, so there's no incremental cost on a new vehicle, and nothing to wear out or need replacing, but it cannot show you actual pressures, and it will be somewhat slow to pick up a condition in which all four tires are equally under-inflated.

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

  4. #14
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    Thanks Uwe, but I am familiar with the difference, had VAG mobiles with both systems, understand how both work.
    What confuses - or raises a question with - me, is that the original post seem to indicate that the Direct system is enabled by the "TPMS 7k3/7k4/7k5 installed/active." bit in CECM.
    Half way through starts to explain "How to swap from the direct to the indirect TPMS system or disable the TPMS system"
    And the swapping instructions boil down to: disable 7k3/7k4/7k5 in CECM and enable 7K6 in ABS.

    Thing is that I have BOTH disabled, yet my Direct system seems to work as intended.
    Maybe I have another variant that's enabled/disabled in a different way?
    Or that bit does something (subtly) different then just outright enable/disable?

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