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TPMS System

52K views 64 replies 29 participants last post by  mazdatech10 
#1 ·
My TPMS alert went off today, and I found that the right rear tire was a few PSI lower than the left rear. However, it was actually still above the recommended PSI. Because the pressure information is inferred from the ABS sensors, I'm not sure exactly how it's determining the pressure. Is it somehow calibrated to figure out the actual pressure, or is it simply monitoring for a difference between left and right tires?
 
#2 ·
It's a nice system on the CX3. Unlike others that have electronic sensors that need tuning to the system, once initiated, our system just derives a difference in wheel speed that a low pressure has on the rolling radius. I've got some interesting PDFs but yes, you've guessed it, the upload limit is too small. I can email you something if you pm me your email address.
 
#10 · (Edited)
TPMS pdf attached.

OK, I’ve now been able to upload pdf’s to the forum. These are for your personal use only.
 

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#11 ·
Anchorman, do you have some information on the TPMS trip thresholds?

At ~80 miles and just now at ~2500miles, my TMPS warning went off, with what seems to be false positives.

The first time, I pulled over, verified visually that no tires were completely flat and drove on. The next day, I checked the cold tire pressures and all tires were 35psi. Subsequently, I reset the TPMS and drove off. I assumed the warning was perhaps due to the dealer not calibrating the TPMS the first time.

Today, my TPMS warning went off again after about 20 miles of freeway driving. I immediately pulled over, checked the tire pressures, and each were at approximately 38psi.

What could be causing the warnings to trigger?
 
#12 ·
If you look at the attached pdf you will see that in operation, the system is fairly robust. However, there is a mis-use prevention function that will throw up regular warning lights. To start, the system is initialised after say changing wheels. The system then goes through 20 minutes of learning what is normal. If a pressure loss is detected it will put the light on as designed. If the system is then initialised, it will detect that somebody is trying to run with a tire deflated and keep sending intermittent warnings. Maybe the system was initialised more than once and it now thinks there is a problem when there isn’t. The pdf suggests that the only way to clear the mis-use warnings is with the Mazda diagnostic tool. There is usually a work around but I can’t access the manual without paying and in that case I like to sit for an hour to get some VFM!

I would try disconnecting the battery for about 20 minutes to let all residual devices power down then after re-connecting, initialise the system again. If that doesn’t work, you’ll have to call at the dealer and let him re-set it until I get time to trawl the manual.
 
#14 ·
I went to dealer on Thursday. Service tech ran Mazda diagnostic and said there nothing to worry about, could have just been cold weather (though it was in the 60s F when the first incident occurred). Anyway, tire pressure is fine in all 4 wheels. Tech said if it happens again and light stays on, leave it on and come back to the dealer.

The also looked at City Brake/Smart City Brake/ Forward Obstruction Warning via Mazda Diag. and said, again no issues. I had been concerned since there are always idiots in front of me stopping suddenly for no apparent reason on highways and such but the proximity warnings fail to sound and the auto-braking fails to engage. The tech suggested I'm further away than I think I am. Perhaps with the long front hood that's the case.
 
#15 ·
Good stuff. Regarding the SCBS, it only works between 19mph and 2mph and less than 20ft. Thats less than one and a half CX3s in front which will feel very close at 19mph!

Ive attached a detailed pdf which gives all the detail on how the system works.
 

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#19 ·
My low tire pressure monitor just went off this evening. I visually checked and everything looked fine. I don't have a tire pressure gauge (but will be getting one) and am taking the car in tomorrow to have it checked. But I'm beginning to wonder if this is going to be constant problem. The warning system in my Subaru was constantly going off. I finally just decided to ignore it and drove it that way for 5 years. Sometimes the light was on, sometimes the light was off. It was definitely weather related then but nitrogen never helped.
 
#20 ·
Its a fairly simple system on the CX3 so until your pressures are checked, I guess we shouldn’t be too concerned.

Is there anything with your car that might effect the weight distribution? i.e. do you carry anything in the boot (trunk)?

Do you drive on unsurfaced roads that might allow one wheel to spin from time to time?
 
#24 ·
Is there anything with your car that might effect the weight distribution? i.e. do you carry anything in the boot (trunk)?
Actually there is something unusual in the trunk that might effect weight distribution. I had a trade show this weekend and have some pop-up booths, roll-up banners and a huge tool chest in my car. It's packed back there and it's quite a bit of weight. If that's it, will the light go off when I take the stuff out?
 
#21 ·
Basically you can swap tires and rims to your heart contents just make sure that every time you mess with wheels (changing tires, rims or pressures) set them to correct pressures and hit the tpms button to put the car in relearn mode. Once in that you'll be fine as its going to learn the new set up. thats what i really like in this system. Just make sure that u only press that relearn button only when you are changing any aspects of your wheel set up. Pressing it just to turn the light off as you drive will cause problems down the line which sometimes require a dealership to manually reset the system (i dont fully understand that part...weird). hope this helps and pimp your ride (tastefully)
 
#22 ·
It's because the system has a "misuse" feature that deters users from cancelling the light when there really is a problem.
 
#23 ·
I understand the missue feature i just wish we didnt always have to hook up a scan tool to reset it. just like updating the CMU which requires pressing 3 buttons and a code it would be easy enough to to tie up a hoist just to reset this system (tieing up a hoist is mainly a problem with us as our dealership shop is tiny of 5 bays that are really close to each other). being able to manually reset it in the service drive in 2 mins would save up time.
 
#25 ·
Depends how much it's effected the rolling radius of the tyres. The early systems measured tyre pressure and transmitted it to the dashboard as a radio signal. The problem was that they could be troublesome and expensive. Our system measures how flat (compared to normal) and the effect it has on rotational speed. If you've kidded it by making a tyre look deflated, it could well flag it as a soft tyre.
 
#26 ·
Ended up not going to the dealer. Couldn't schedule an appointment with one of them. The other, when told that the tire was at 40psi when the TPMS warning came on, said that 40psi was too high and is the cause of the warning. ...which is wrong, so no point in going. I reset it again and so far so good with no warning after about 800 miles.
 
#27 ·
40 psi sounds high to me. Where have you got that info? The correct pressure is written on the door frame sticker.
 
#33 ·
Never had a problem. I changed to winter wheels and the system seems to have accepted them too.
 
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