[Swiller]

evnin all.

yes i have searched on here and cant find any specific answers to the problem.

I have ps2's on the motor, non rfts. since a huge downpour a week or so ago when i was on the motorway, teh tyre pressure sensor comes on every few days. i have checked the pressures and one did need pumping up, so i pumped it and reset the tyre pressure system.

since then, no air has left the tyres, but the ligght keeps coming on. I am thinking that there may be a specific method of re setting the sensor, rather than pressing it for a few seconds and waiting for the tick.

have read somewhere it may be alignment, but i think it is more to do with the drive home in some serious rain, when the car did hit a few puddles on the motorway at high speed.

any ideas?

cheers

[doughboy]

The pressure monitor uses the ABS sensors, so they are working or you would have more warning lights.

How do you know no air has been lost? are you checking the pressures?

Have you reset it properly? sounds ok if you have the tick in the intialising idrive box.

[HighlandPete]

Sounds as if you are not setting the system correctly. Do you run the engine, get the tyre check control and get the tick then hold until tick re-appears and drive off to initialise?

HighlandPete

[Swiller]

thanks guys. the process for resetting is via the indicator stick, dial the menu,press once, then press again and keep pressed until tick appears. this is a non i drive car.

I know no air has been lost as the light has been on 5 times and after time 1, i have been checking the tyres every day, with a consistant 38 psi. The light comes on every few days irrespective of tyre pressure.

All times that i have reset are after about 60-100 miles on mway. I just park up , and put auto gearstick into park, and do the resetting as described above. Is there more to it than that?

Thanks

Swiller

[zltm089]

hmm...i think you should reset it before you even drive the car....

check the pressure in all tyres, then press the reset button....and then drive off...

I had some issues aswell....


I recently changed a tyre....(replaced by kwik fit) and i didn't touch the reset ...i just drove off....the light came on after a few miles!!!....

I've reset it, and it hasn't been on since...

Do check your tyre pressures every 2-3 days, as these tyre pressure monitors aren't that reliable...

[carl_d]

Originally Posted by Swiller

thanks guys. the process for resetting is via the indicator stick, dial the menu,press once, then press again and keep pressed until tick appears. this is a non i drive car.

I know no air has been lost as the light has been on 5 times and after time 1, i have been checking the tyres every day, with a consistant 38 psi. The light comes on every few days irrespective of tyre pressure.

All times that i have reset are after about 60-100 miles on mway. I just park up , and put auto gearstick into park, and do the resetting as described above. Is there more to it than that?

Thanks

Swiller

38psi all round? Normally fronts are lower than rears! If not this is your problem as the ABS system compares the rotation size (circumference) of each wheel against each other wheel and against pre-set values, if any one wheel or group of wheels is out then the light will come on.

[Swiller]

Thanks for replies . All were 38 psi. Took it down kwik fit today, as I got up this morning and the back rear had deflated which is why the indicator came on yesterday. Still doesn't explain why even when tyre pressures ok, it still came on for the previous times. Kwik fit diagnosed a very slow puncture in back rear and pumped front and rears appropriately. They also checked the sensors and stuff to fix any loose connections. Just hope the bugger doesn't come on again, but have a suspicion it will.

[carl_d]

Originally Posted by Swiller

Thanks for replies . All were 38 psi. Took it down kwik fit today, as I got up this morning and the back rear had deflated which is why the indicator came on yesterday. Still doesn't explain why even when tyre pressures ok, it still came on for the previous times. Kwik fit diagnosed a very slow puncture in back rear and pumped front and rears appropriately. They also checked the sensors and stuff to fix any loose connections. Just hope the bugger doesn't come on again, but have a suspicion it will.

They should NOT be all 38 psi. Fronts should be lower!!! This is why the light is coming on after pressures are set. Check the sticker on the B-pillar for the correct pressures.

[Swiller]

Originally Posted by carl_d

They should NOT be all 38 psi. Fronts should be lower!!! This is why the light is coming on after pressures are set. Check the sticker on the B-pillar for the correct pressures.

After a 200 mile necessary geoff (hoon) today, all is well, no warning lights at all. Seems you were spot on Carl. Kwik fit did tell me they set the fronts lower than backs and all was spot on when I checked this morning. I thought the electronics were starting to play up, which has always been a right pita on beemers. So cheers ++. I never realised the pressures were different front and back, and rarely pump em up myself. When I did , that's when it went wrong lol.

[doughboy]

Originally Posted by carl_d

They should NOT be all 38 psi. Fronts should be lower!!! This is why the light is coming on after pressures are set. Check the sticker on the B-pillar for the correct pressures.

The system doesn't know actual pressures so it doesn't know if you are complying with the rating plate!!!!

It only senses a change in wheel speed / pressure since the last reset was done.

So if you put the fronts at 40psi and the rears at 20psi and reset it, the system would be quite happy with that until one tire speed / pressure changes.

Thats why its vital you reset it every time you adjust pressures or change a tire.

[carl_d]

Originally Posted by doughboy

The system doesn't know actual pressures so it doesn't know if you are complying with the rating plate!!!!

It only senses a change in wheel speed / pressure since the last reset was done.

So if you put the fronts at 40psi and the rears at 20psi and reset it, the system would be quite happy with that until one tire speed / pressure changes.

Thats why its vital you reset it every time you adjust pressures or change a tire.

It also has predefined min/max range values for speed differences between wheels and these are used in addition to monitoring the sampled values collected after reset. Both are used to determine incorrect pressures warnings. In the case above, over inflation of the front tyres would case the system to doubt correct inflation - out of normal range values will occur - this will trigger an amber warning light. In other words, the front wheels are rotating slower than the rear wheels. Built-in to the system, there is an acceptable range for the speed difference between front and rear wheels and this rule is being broken. In this case, it's all about comparing the rotational speed difference between the front and rear wheels. Both methods are used in the system.

[doughboy]

That can't be possible IMO? The car only knows reported wheel speed of each wheel, no more. It doesn't know wheel size.

Even if all the wheels were the size of hula hoops they would all have the same rotational speed, and the car only has this wheel speed as a reference so it could not find any fault.

Again, change the wheels for tractor tyres and the same goes.

It can only be a relative system, if ALL the tyres are equally flat it cannot know they are flat, same goes for over inflated or bald etc.

[chris330D]

I think people are getting a bit misled here. BMW calls the system TPMS, tyre pressure monitoring system but it does not monitor the tyre pressures in the UK. It is a different system in the US. The UK system using the ABS sensors, these measure the speed of each wheel. If a wheel is turning at a different speed to another it is assumed that is because it has lost pressure. It is a relative, inferrred measurement. It has no way of knowing the actual pressure. HTH

[HighlandPete]

Originally Posted by chris330D

I think people are getting a bit misled here. BMW calls the system TPMS, tyre pressure monitoring system but it does not monitor the tyre pressures in the UK. It is a different system in the US. The UK system using the ABS sensors, these measure the speed of each wheel. If a wheel is turning at a different speed to another it is assumed that is because it has lost pressure. It is a relative, inferrred measurement. It has no way of knowing the actual pressure. HTH

BMW now use the term TPWS, Run-flat tyres with Tyre Puncture Warning System... not TPMS.

Should help reduce the confusion. We still need to check pressues regularly.

HighlandPete

[acerboo]

has anyone tried the tyrepal monitoring system, am considering this as it gives tyre pressure for each tyre and the temperature, especialy useful if you are running non runflats

[hmi1750]

I have the warning coming on every few weeks. Normally after I hit a patch of mud or something and one wheel slips.. then short way down the road it warns me with a red tyre deflated symbol! Scares me and I carefully drive home, check and check again next day and all tyres are fine so I reset it. But it is a rubbish system! VAG one is far superior and tells you which wheel is deflated.

[doughboy]

Originally Posted by chris330D

I think people are getting a bit misled here. BMW calls the system TPMS, tyre pressure monitoring system but it does not monitor the tyre pressures in the UK. H

TPMS is a generic term used by the tire industry to signify any type of inflation monitoring AFAIK.

So the method it uses isn't too important.

[chris330D]

I agree it is a generic term but it seemed from the posts that people thought the BMW system fited to our cars was measuring the tyre pressure which it is not.

[e92_grn]

Originally Posted by HighlandPete

Sounds as if you are not setting the system correctly. Do you run the engine, get the tyre check control and get the tick then hold until tick re-appears and drive off to initialise?

HighlandPete

I'm surprised about the need to hold (the I-Drive controller?) until the tick appears - nothing about that in the owner's manual. Is this an undocumented feauture? I'm now concerned mine is not properly initialised either!

[HighlandPete]

Originally Posted by chris330D

I agree it is a generic term but it seemed from the posts that people thought the BMW system fited to our cars was measuring the tyre pressure which it is not.

I'd agree many have got the wrong idea of what the system does, I'm not even sure BMW have made it clear how important checking pressure really is. I've read in some of the trade info' that these systems have meant even more neglect, users now not even bothering at all, as "the car will tell them" when to pump up the tyres.

HighlandPete

[HighlandPete]

Originally Posted by e92_grn

I'm surprised about the need to hold (the I-Drive controller?) until the tick appears - nothing about that in the owner's manual. Is this an undocumented feauture? I'm now concerned mine is not properly initialised either!

Ah... I'm thinking of the resetting method using the indicator stalk and the check system. (Which is definitely documented in the manual). Using I-Drive how do you know the 'INIT' check is ready for drive off?

HighlandPete

[e92_grn]

Originally Posted by HighlandPete

Ah... I'm thinking of the resetting method using the indicator stalk and the check system. (Which is definitely documented in the manual). Using I-Drive how do you know the 'INIT' check is ready for drive off?

HighlandPete

Hi,
It says something to the effect of "Init complete" then a picture of all the wheels go green!!!...I'm going to have to go and do that now, just to check!