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Neil1210

Ford tpms

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Hi I have a 2015 fiesta with tpms. Just wondering how they worked and when are they triggered. 

Do they only tell you when your tyres are flat 

Or when they are going flat down on psi

And if so does it tell you what tyre

I had 1 tyre a few psi down compared to the rest and nothing came on. Would be interested to know how they worked. 

As my old toyota used to tell me current psi and temp and what tyre. 

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Most of them now use the ABS sensors to detect rotation speed. You have to set it up to say pressures are correct then it will monitor rotation against other wheel on the same axle.

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OK got you. Thanks for that it. If its 25%that would explain why it had not gone off. Tyre was at 32 pumped up at last reset and when I done my checks it was 27.

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TPMS is a complex subject because there are two main types and then  variations within those. Much of the on line information available is misleading as the author often is unaware of other systems than the specific one they are writing about.

The ABS system uses sensors on the vehicle axles to monitor variations in tyre speed rotation caused by differing diameters between the inflated circumference and a deflated one.

The in tyre system, as used on a 2015 Fiesta, is a different system based on a transmitting sensor mounted within the tyre. The fiesta uses a small device that is attached to the tyre valve and which incorporates a battery, a motion activated switch (conserves battery when stationery) a pressure sensor/monitor, a radio receiver and transmitter.  (Not bad for £5 from China or £20 in GB!)

After inflating the tyre and actioning the reset process (in the dashboard information system) the base pressure is set; if the tyre deflates significantly whilst the car is moving, the sensor transmits a warning to a receiver in the cars electronic module and causes the dash display and computer display to indicate.The receiver and display function may be a basic single warning and is not very accurate,but an improved system (on later models) has a separate display for each tyre and actually displays the tyre pressure of each individual tyre on request. (The sensors are not inter-changeable. for these two versions)

The sensor batterys last 5-10 years but are not replaceable. The sensors are readily available from several manufacturers but do need to be the appropriate one for the specific car. They need to be individually programmed with an identity, so that the receiver module in the car is not reading the wrong tyre or even adjacent vehicle. Some vendors will do this. The sensor, having been fitted to the wheel, then needs to be partnered to the receiver; unfortunately this may need an OBD or similar specialist tool to instruct the tyre sensor to responds and transmits to the in car sensor /modem which then can lock into the response.

Some car models (including 2014/15 Fiestas)* benefit from an auto re-learn programming system, that causes the above pairing to occur once the car computer has been set into a relearn mode. Unfortunately the procedure to put the car into this mode varies between makes and models, but usually is a sequence of rapidly turning on/off the ignition and electrics switches .

*FYI--that Fiesta, if key  start ignition, is--- , Handrake on, ignition on/off twice,ignition on.Footbrake on/off,ignition off. Repeat but leave ignition in on position at end.(Do not start engine, Horn should bleep once.If not or twice, start again.Procedure must be done smoothly and very quickly. Several attempts may be needed. Drive for 10 mins minimum immediately.

As the  tools are expensive (basic OBD readers are not sufficient) the garages tend to charge £60-£120 to change a sensor.

 

 

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On the Mk8 you can see on the information screen on dash for each tyre from pressure sensors. i understand the Mk 7.5 had pressure sensors in them too, not sure how you check them.

I have a question. Does/should the spare wheel have a pressure sensor in it? Will the computer get confused when it is swapped, if it had one? I have the spare from my brothers old mk6 which doesn't have one.

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Good point. I have a full size spare wheel. I was planning on putting it on an alloy and getting rid of the spare steel wheel. I would not think it had tpms as its for an emergency 

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The TPMS controls the 4 tyres, if 1 tyre have pressure -0.3 psi, you will get a warning.

I have a slow flat tyre, and that help me a lot.

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