My 407 coupe had tyre pressure monitors (that seem to be behaving themselves). Washing the car today got me thinking about changing a wheel and how they actually work. I checked the manual and there was no mention of having to disconnect anything. It did say that with the spare on, I will get a warning that the wheel is effectively 'missing'. It also said (predictably) that I should consult my dealer when changing tyres.
So how do they work and can an old tyre fitter put new tyres on. (Cars only got 800 miles on it so far, so no worries yet)
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According to an Alfa forum, the valves are special and transmit the pressure wirelessly. I do feel slightly sceptical about that, though.
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BMW (and MINI) ones work by using the ABS sensors to detect changes in the rate of rotation of each wheel A tyre that is deflating/has deflated will have a different rolling radius and will therefore set off the tyre pressure warning system. However earlier Renault systems did use special tyre valves that transmitted wirelessly to the car, though I don't know if they still do, so I suppose either could be used by Peugot...
Peter
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I'd have thought the ABS-derived system described by Peter S (on my MINI and my BM) would be the most logical way to go. But is any other feasible? Wi-fi? Ya gotta be kiddin'! Sensitive electronic kit on a wheel subjected to continual assault from the elements and road irregularities? Nah, surely not.
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Wi-fi? Ya gotta be kiddin'! Sensitive electronic kit on a wheel subjected to continual assault from the elements and road irregularities? Nah surely not.
'fraid so:
www.answers.com/topic/tyre-pressure-monitoring-sys...m
Not sure about BMW's, but all MB's are capable of the passive type (whether it was specified or not, the data is there, from the traction control etc systems). The active system, if specified, uses radio technology to monitor the pressures.
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The Renault ones are still wireless, and still useless. Our Grand Scenic has had the system disabled and the transmitters removed thankfully.
That BMW system is pretty clever. It takes some pretty carefully designed logic to be able to detect the miniscule change in rolling radius by say a 3psi drop in pressure, while avoiding false alarms when cornering hard or accelerating hard on variable grip surfaces with the traction control turned off.
Physically it should be a much more reliable and robust solution than Renault's though. Which itself is neither.
Cheers
DP
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Pointless things. Tyre fitters hate them as they frequently snap off as the plastic gets brittle with age. People should use a presssure gauge, a pair of eyes and some common sense.
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Some of us still do!! It was just an idle query about how they work.
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The system on our C5 has recently started playing up, periodically telling me that the tyres are deflated. However, it only displays this message for a second or two, so no real problem.
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They are a pain in the backside if you change a wheel after a puncture you get warnings flashing at you, if you change the wheels around the same effect if you take the wheel to far away from the car during any work you may be doing they lose the connection and have to be reset and if your local tyre fitter is not aware of them he'll break them.Having said all that the ones on the Renault I am running at the moment are working fine and told me correctly I had an under inflated tyre.
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Well, wi-fi... I'm amazed. Thanks.
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Honestly can't see the point.
Headlights that come on when it gets dark. We use to call that an on-off switch. It takes 1.2 secs to operate.
Wipers that come on when it rain. We use to call that an on-off switch. It takes 1.2 secs to operate.
And when they go wrong it does not take 2 hours at £95 per hour to replace the £450 electronic black boxes.
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>>Pointless things.
>>Honestly can't see the point.
I totally disagree! IMO they should be made mandatory on all new cars.
Almost every day I see vehicles with obviously significantly under inflated tyres.
I can only assume these drivers cannot feel any problem with the cars handling.
I would hope that a warning on the dash might just generate some action to sort things.
( assuming unlike the " rear fog light on" that it is noticed ) ;-((
For the first time I have a car with lower profile tyres and have no clue apart from using a guage if the tyres have lost a little pressure.
The quick look around will only tell me if a have a totally flat tyre on the front.
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>>Pointless things. >>Honestly can't see the point. I totally disagree! IMO they should be made mandatory on all new cars.
Not much use if they aren't reliable though, are they? When mine started playing up, I stopped the car the first time to find that I didn't have a puncture, or underinflated tyre. Now, when I get the message that the tyres are deflated (yes that's right, tyres not tyre), I know it will be wrong, so it is ignored, so no use at all.
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Wipers that come on when it rain. We use to call that an on-off switch. It takes 1.2 secs to operate.
These are a pain if they don't work properly. Adjustable intermittent wipe is a much better idea.
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I love the auto lights and wipers on the 407 coupe. Never had them before. The wipers vary there speed automatically and are proving very efficient.
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Have a friend with a 2004 Audi A4, which he bought "pre-pimped" with 20" wheels on (it looked ridiculous, and the front tyres touched the wheelarch at full lock, but thats not my point). The sensors in the wheels hadn't been reconfigured for the different rolling radius, and the computer used to go mad with errors. He braked on a dual carriageway and the servo assistance shut down because of it (like trying to brake in a broken down car thats being towed, powerless, with no servo assistance, but at 70mph. i.e. nothing happens). After coasting to a stop, restarting the engine fortunately rebooted the computer, and he took it to Audi. Another reason why the good old fashioned methods are best.
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I love the auto lights and wipers on the 407 coupe. Never had them before. The wipers vary there speed automatically and are proving very efficient.
They will be fine until they stop working properly, then they will be a pain.
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They will be fine until they stop working properly then they will be a pain.
My experience of Avensis auto-wipers - four sensitivity settings are available. The least sensitive is still more than willing to go into high-speed flap-flap mode when faced with average Mway spray from a HGV. The same setting is equally capable of ignoring a complete windscreen covering of larger raindrops at 30mph. As for the higher sensitivities, they are just far too 'excitable' for me. In all honesty the auto-wipers are useful (in a lazy way) 80% of the time - the rest of the time I would be happier with adjustable intermittent. It would be a great improvement if the least sensitive mode ruled out the highest-speed wiper setting.
It could be that Toyota's implementation of auto-wipers is particularly poor, but I don't see any particular reason why that should be so I remain to be convinced that any of them would pass muster for me.
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Mine work fine, with no problems. If I ever get fed up with them, I can just resort to the normal on/off switch.
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Mine work fine with no problems. If I ever get fed up with them I can just resort to the normal on/off switch.
Out of interest, do yours ever kick into the highest speed mode? That is the thing that irritates me most by far about mine.
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They've only ever operated at a suitable speed, getting faster or slower as necessary. Fingers crossed!
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Both our Citroens have auto wipers. SWMBO's anticipate every single wipe or speed change exactly as you would want... brilliant. Mine are always half a second behind the event and trigger a move of the fingers towards the stalk just before they do the business.... slightly irritating.
David
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They've only ever operated at a suitable speed getting faster or slower as necessary. Fingers crossed!
The problem is when they don't work properly, there is only one choice, on or off. There is no intermittent wipe available (i.e. not one that will work properly).
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Seem to recall that the first mass produced car fitted with an on-board tyre pressure system was a Chevrolet Corvette - apparently in its earlier forms the first mass produced car with a fibreglass body and fuel injection...what a mine of useless information!
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The problem is when they don't work properly there is only one choice on or off. There is no intermittent wipe available (i.e. not one that will work properly).
That's the crux, if intermittent was also fitted I would grumble less.
Get the feeling that I am unusually critical of the wipers kicking in to high speed mode where others find this quite acceptable. In a non-auto wiper car I would go years without using the highest speed setting. It really takes a monsoon for me to consider it necessary - probably used it 5-10 times in 17 years of driving. Therefore, the fact that the auto wipers use it even on low sensitivity really gets up my nose - I find the highest speed more distracting than useful.
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Therefore the fact that the auto wipers use it even on low sensitivity really gets up my nose - I find the highest speed more distracting than useful.
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Gets up my nose too. Adjustable intermittent is eminently preferable.
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