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2014 C4 GP - Tyre pressure monitor, outside temp & wing mirrors

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chrislufc1977   
Sun Apr 21 2019, 03:47am
Member No: #53433
Joined: Mar 31 2019
Location: Cambridge
Hi all,

Just wondered if there is a link between the tyre pressure monitor, outside temp & wing mirrors?

After adjusting the wing mirrors I noticed the the tyre under-inflation monitoring warning and service light came on. At the same time I also lost the outside temp (displays 3 dashes). If I fold in the wing mirrors using the button inside the car the tyre pressure warning goes off again and the outside temp returns to normal!

Wondering if there is a loose connection in the wing mirrors somewhere. Has anyone else experienced this?

Many thanks
Chris
proinnsias   
Mon Apr 29 2019, 06:05am
Member No: #43821
Joined: Feb 21 2016
Location: Dublin
Tyre pressures are measured from wheel rotation speed by the ABS sensors
Wing mirror temp sensor will be entirely separate

How's your battery? Random faults like that could be related to an iffy battery...
GrantO   
Fri Aug 02 2019, 08:02am
Member No: #54328
Joined: Aug 02 2019
Location: Falkirk
Hi, just wondering if the original poster had any update on this?

My 2013 C4 Picasso has just failed its MOT due to a tyre pressure warning system fault message (which I have to admit to ignoring for several months as I didn't realise it was a fail, and have just been checking my tyre pressures manually as I've been doing for the past 30 years...).

It appears every time I start the car, and then the Service light and under inflation icon remains on on the dashboard when driving.

However, at the same time as this started to happen, I also lost my external temperature display, which now just displays two lines.

I had put it down to coincidence, but after reading this post I was wondering if there is some obscure link between the two?

The folding the wing mirrors workaround doesn't help on mine, and I will get the battery checked, but was hoping the original poster might have an update?
proinnsias   
Mon Aug 05 2019, 08:00am
Member No: #43821
Joined: Feb 21 2016
Location: Dublin
Tyre pressures are a function of the ABS setup

Don't panic ... if the tyres are set to the correct pressures - go to the vehicle settings menu - and re-initialise ... it tells the computer that the values it sees at about 30km/h and over are "normal" and expected (ABS measures the wheel rotation speeds for each wheel)
An under-inflated tyre will rotate at a different speed to keep-up with the others - causing the ABS sensors to notice, and the light to come on.
You should really reset every time you set the pressures, and certainly any time you change tyres.

External temp sensors are in the wing mirrors and shouldn't be related ... it's possible a wire has been crimped by the folding mechanism (it's delicate enough considering the size and weight of the mirrors!
GrantO   
Fri Aug 09 2019, 04:40am
Member No: #54328
Joined: Aug 02 2019
Location: Falkirk
proinnsias wrote ...

Tyre pressures are a function of the ABS setup

Don't panic ... if the tyres are set to the correct pressures - go to the vehicle settings menu - and re-initialise ... it tells the computer that the values it sees at about 30km/h and over are "normal" and expected (ABS measures the wheel rotation speeds for each wheel)
An under-inflated tyre will rotate at a different speed to keep-up with the others - causing the ABS sensors to notice, and the light to come on.
You should really reset every time you set the pressures, and certainly any time you change tyres.

External temp sensors are in the wing mirrors and shouldn't be related ... it's possible a wire has been crimped by the folding mechanism (it's delicate enough considering the size and weight of the mirrors!

Hi,

Just to clarify the tyre pressure warning I was referring to was a monitoring system fault (and therefore an MOT fail), not simply a warning that one or more tyres were underinflated...the warning did not go away after a recalibration.

However, you were correct about it being a broken wire in the wing mirror...I took it to an auto electrician earlier this week, mentioned that I thought the external temperature and tyre pressure monitoring fault might be related as they started at about the same time...he said it was highly unlikely, but found and fixed the broken wire, and guess what...? I now have a working external temperature and no tyre pressure monitoring system fault! There must be some obscure link, but he can't explain it and says it's one of the most bizarre things he's seen on a car!

Anyway, hopefully the above might help others, and hopefully I'll get my MOT pass OK now!
1 User said Thank You to GrantO for this Post :
 chrislufc1977 (10 Aug 2019 : 08:56)
iscom   
Fri Aug 09 2019, 04:51am
Member No: #20936
Joined: Jul 21 2011
Location: Ireland Fermanagh & Galway
Maybe temp and tyre pressure are related because of the temperature can affect tyre pressure (ie always take pressure when cold ) so maybe it adjusts to taking account of the outside temp
chrislufc1977   
Sat Aug 10 2019, 09:01am
Member No: #53433
Joined: Mar 31 2019
Location: Cambridge
GrantO wrote ...

proinnsias wrote ...

Tyre pressures are a function of the ABS setup

Don't panic ... if the tyres are set to the correct pressures - go to the vehicle settings menu - and re-initialise ... it tells the computer that the values it sees at about 30km/h and over are "normal" and expected (ABS measures the wheel rotation speeds for each wheel)
An under-inflated tyre will rotate at a different speed to keep-up with the others - causing the ABS sensors to notice, and the light to come on.
You should really reset every time you set the pressures, and certainly any time you change tyres.

External temp sensors are in the wing mirrors and shouldn't be related ... it's possible a wire has been crimped by the folding mechanism (it's delicate enough considering the size and weight of the mirrors!

Hi,

Just to clarify the tyre pressure warning I was referring to was a monitoring system fault (and therefore an MOT fail), not simply a warning that one or more tyres were underinflated...the warning did not go away after a recalibration.

However, you were correct about it being a broken wire in the wing mirror...I took it to an auto electrician earlier this week, mentioned that I thought the external temperature and tyre pressure monitoring fault might be related as they started at about the same time...he said it was highly unlikely, but found and fixed the broken wire, and guess what...? I now have a working external temperature and no tyre pressure monitoring system fault! There must be some obscure link, but he can't explain it and says it's one of the most bizarre things he's seen on a car!

Anyway, hopefully the above might help others, and hopefully I'll get my MOT pass OK now!



Hi there.

Was it in the driver’s side wing mirror? I haven’t had a look at mine yet but guessing the wires are being stretched or pinched when the mirrors fold.

Will take a look inside and see what’s what!

Thanks,
Chris
neilp   
Sat Aug 10 2019, 09:13am
Member No: #3384
Joined: Apr 21 2008
Location: Bulwell, Nottingham
External temp sensor is usually on the passenger side mirror. (drivers side for Europe)
routemaster1   
Sat Aug 10 2019, 10:23am
Member No: #574
Joined: Jul 08 2007
Location: Dorset
neilp wrote ...

External temp sensor is usually on the passenger side mirror. (drivers side for Europe)

Other way round, Neil. Drivers door in UK, probably passenger door in Europe.
DeuxChevaux   
Sat Aug 10 2019, 10:46am
Member No: #16472
Joined: Nov 21 2010
Location: North Norfolk UK
proinnsias wrote ...

Tyre pressures are a function of the ABS setup



That depends on the age of the vehicle. Earlier ones have a sensor inside the wheel certainly until the end of 2015 although I am not sure when the change to ABS sensor monitoring happened for all models
neilp   
Mon Aug 12 2019, 10:55am
Member No: #3384
Joined: Apr 21 2008
Location: Bulwell, Nottingham
routemaster1 wrote ...

neilp wrote ...

External temp sensor is usually on the passenger side mirror. (drivers side for Europe)

Other way round, Neil. Drivers door in UK, probably passenger door in Europe.

Sorry, yes. Messed that up didn't I.
 

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