1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Tyre Pressure monitors - How do they work?

Discussion in 'Wheels, Tyres, Brakes & Suspension' started by dvb247, Feb 15, 2011.

  1. dvb247

    dvb247 Hardcore MB Enthusiast

    Messages:
    364
    Joined:
    Aug 1, 2009
    Location:
    Cheshire
    Car:
    AMG e55
    I have gained much notoriety on this site for my Rimstock wheel refurb tale of woe and the members wonderful support along the way, now I finally have my rims back I need to understand how the tyre preasure monitors work, the reason for this question was that when I removed my wheels some 5 weeks ago I wrote on each sensor which corner the wheels came off with tipex, now back the sensors are in a bag with the tipex rubbed off:dk:
     
  2. richard

    richard Authorised Forum Sponsor Authorised Forum Sponsor

    Messages:
    5,510
    Joined:
    Jun 10, 2002
    Location:
    Berkshire, UK
    Car:
    MY04 SL55, MY17 GLC250d AMG Sport
    Each sensor has a unique serial number. (When new, this is in a sticker on them)

    The control unit needs to know which serial number is for which wheel ..

    There is a procedure in Star Diagnosis to identify wheel sensors, because they only transmit when pressure changes, so the procedure involves leaving car for a period of time so the sensors go to sleep, reduce the pressure in one tyre so it starts transmitting, use Star to find out what the ID is and write it down, wait for a period of time so the sensor goes to sleep, repeat for all wheels. Once done, tell the tpm control unit which wheel is which ID.

    Remember they also have limited battery life !

    Richard
     
  3. OP
    OP
    dvb247

    dvb247 Hardcore MB Enthusiast

    Messages:
    364
    Joined:
    Aug 1, 2009
    Location:
    Cheshire
    Car:
    AMG e55
    Thanks Richard, totally understand that, one question though, "limited battery life" how long do they last as the car is 6/7 years old and these were fitted as standard?
    I do check the preasures on the dash sometimes so does that kick the battery into life for a couple of mins then shut off so to last for years?
     
  4. richard

    richard Authorised Forum Sponsor Authorised Forum Sponsor

    Messages:
    5,510
    Joined:
    Jun 10, 2002
    Location:
    Berkshire, UK
    Car:
    MY04 SL55, MY17 GLC250d AMG Sport
    Once initially activated (i.e first inflated) they then use battery slowly, and they transmit a burst of info for a few minutes after the pressure changes. Some types also transmit temperature. I think 6-7 years is potentially their life - but I am not 100% sure. I changed mine at around 5 years because I was putting different wheels on the car.

    Richard
     
  5. Alps

    Alps MB Club Veteran

    Messages:
    6,906
    Joined:
    Nov 29, 2002
    Location:
    London\Essex
    Car:
    E63 Weistec AMG, E55 2004 Silver(SOLD), C36 AMG 1997 (SOLD)
    dvb, a subject ive been getting fairly familiar with!
    #
    one of my sensors died (battery) just before xmas, another just after xmas, and whilst getting that one replaced another has gone! one was replaced 2 years ago, so essentially i now have 4 x newish sensors!

    the procedure on star is as richard has stated, my sensors have died after 7 years so not bad, what color were your sensors, if they were grey then they havent nbeen changed and are prob original, if orange they will have been changed at some point!
     
    1 person likes this.
  6. npuk

    npuk Hardcore MB Enthusiast

    Messages:
    4,239
    Joined:
    Nov 12, 2009
    Location:
    London
    Car:
    A180 CDI Avantgarde SE (2008)
    It is said they last around 5yrs but clearly can last longer. Many people dont replace them when they die but you will need to have the system disabled via STAR if you choose not to.

    You can get replacement sensors and valve kits a little cheaper from: Alloy Wheels Direct Ltd | TPM Sensors | Tyre Pressure Monitor
     
    1 person likes this.
  7. MrML

    MrML Active Member

    Messages:
    90
    Joined:
    Jul 15, 2010
    Location:
    West Sussex
    Car:
    ML350 Sport
    I am afraid I just put petrol in and wait for the service indicator to come on. This talk of tyre pressure indicators has made me curious enough to just go outside to check...
    On the computer display thing it says "Run flat indicator active". Does this mean my sensors are all up to scratch and can continue to kick the tyres ?
     
  8. npuk

    npuk Hardcore MB Enthusiast

    Messages:
    4,239
    Joined:
    Nov 12, 2009
    Location:
    London
    Car:
    A180 CDI Avantgarde SE (2008)
    Not all cars have the TPMS system. The TPMS system and the Run flat indicator are two different systems. Your car user manual will have info on how the run flat indicator works and how to reset it after adjusting your tyre pressure. It works off the ABS wheel sensor and doesnt have an actual sensor on the alloy wheel like the TPMS system.
     
    Last edited: Feb 15, 2011
    1 person likes this.
  9. MrML

    MrML Active Member

    Messages:
    90
    Joined:
    Jul 15, 2010
    Location:
    West Sussex
    Car:
    ML350 Sport
    Thank you - I will have a read tomorrow
     
  10. markjay

    markjay MB Club Veteran

    Messages:
    16,253
    Joined:
    Jun 24, 2008
    Location:
    London
    Car:
    W204 C180 Executive SE 2013 Automatic / COMAND NTG4.7 and Morel speakers fitted by www.comand.co.uk
    Indeed. On my W203 it was a simple STAR mod done by Alfie, activate the tyre pressure monitoring. As said by npuk, this is a simple system not based on TPMS sensors in the wheels, instead the system relies on the ABS sensors and detects if one wheel spins at different speed to the other three.

    It will not tell you what the actual pressure is because it does not know. It will also not know if the pressure is actually correct or not. And if all your tyres loose pressure at the same time, it will not detect it ether. All it can do is tell you that one tyre seems to have less air than its siblings.
     
  11. 350_Coupe

    350_Coupe Hardcore MB Enthusiast

    Messages:
    769
    Joined:
    Oct 31, 2010
    Location:
    Oxfordshire
    Car:
    2005 C350 Coupe SE
    That system Mark described will the the type on my C Class Coupe, which i'll get activated at some point, it would be nice to be able to fit the other system with the sensors as i think it is more acurate and more useful (even mercedes disable the non-sensor system on cars in this country)

    General question, is it possible to change the batteries n the sensors ? because i would have thought so, but someone mentioned the colour of the sensor as a way to tell
     
  12. npuk

    npuk Hardcore MB Enthusiast

    Messages:
    4,239
    Joined:
    Nov 12, 2009
    Location:
    London
    Car:
    A180 CDI Avantgarde SE (2008)
    It is disabled as standard as Mercedes listed it as an optional extra even though all they do to activate it is enable it in STAR! It was a £40 option in the pre-facelift W169. More recently though it comes activated as standard.

    The sensor batteries cant be changed. Regarding retrofitting in a car that didnt have TPMS as a factory option I dont think it would be possible in STAR to enable the system as it is not an option for your car. Best check with Alfie or Richard before you do it.
     
    Last edited: Feb 16, 2011
  13. 350_Coupe

    350_Coupe Hardcore MB Enthusiast

    Messages:
    769
    Joined:
    Oct 31, 2010
    Location:
    Oxfordshire
    Car:
    2005 C350 Coupe SE
    ok cheers, it was more a curiosity thing :D

    i'll probably get the non-sensor thing enabled when i visit them at some point
     
  14. OP
    OP
    dvb247

    dvb247 Hardcore MB Enthusiast

    Messages:
    364
    Joined:
    Aug 1, 2009
    Location:
    Cheshire
    Car:
    AMG e55
    Mine are indeed orange so they must have been replaced at some point, they work very well, when I got my double blow out last month from the now infamous pot hole the dash lit up straight away!
     
  15. zebmapara

    zebmapara Member

    Messages:
    56
    Joined:
    May 8, 2010
    Location:
    london
    Car:
    w203 2006 c180 avan
    NPUK, were was yo activated
     
  16. npuk

    npuk Hardcore MB Enthusiast

    Messages:
    4,239
    Joined:
    Nov 12, 2009
    Location:
    London
    Car:
    A180 CDI Avantgarde SE (2008)
    It comes activated as standard on the post facelift W169. If you need it done (assuming it was an option for your car) anyone with STAR can do it.

    Can highly recommend Alfie and Richard at Comand.co.uk based in Woking, Surrey. www.comand.co.uk
     
  17. Cabe

    Cabe Hardcore MB Enthusiast

    Messages:
    478
    Joined:
    Jul 29, 2010
    Location:
    Portsmouth
    Car:
    W202 C220 CDI
    [​IMG]

    Not sure where the battery goes in mine.....
     
    1 person likes this.
  18. 350_Coupe

    350_Coupe Hardcore MB Enthusiast

    Messages:
    769
    Joined:
    Oct 31, 2010
    Location:
    Oxfordshire
    Car:
    2005 C350 Coupe SE
    hahahaaha nice one Cabe !

    As for the dashboard lighting up when you hit a pothole, it's not good is it, when you know you don't even need to get out to see if there has been any damage caused by running through another pothole on one of this countries p*** poorly maintained roads, for what the government steals from the motorist each year, they should not need to build any new roads for the olympics, because we should already have a road system far in advanced of any other country.... but no, they waste that money supporting foreign free loaders instead of sticking a size 12 boot up their a*rse

    speaking of potholes btw, Check this site out for a laugh :)
     
  19. markjay

    markjay MB Club Veteran

    Messages:
    16,253
    Joined:
    Jun 24, 2008
    Location:
    London
    Car:
    W204 C180 Executive SE 2013 Automatic / COMAND NTG4.7 and Morel speakers fitted by www.comand.co.uk

    +1 :thumb:
     
  20. phaseone

    phaseone Active Member

    Messages:
    67
    Joined:
    Feb 12, 2012
    Location:
    Surrey
    Car:
    CLS500 AMG
    I know this is an old thread but does anyone know of a refit kit for these valves as I have one that is leaking air around the base
     

Share This Page