ND tyre pressure monitoring system (TPMS)

davekmoore · Postby **davekmoore** » Sat Apr 16, 2016 8:38 pm

Several of my ND customers have reported the TPMS warning light coming on, especially after 10+ mins of spirited driving. I tell them how to check the pressures and put it out and after that never hear from them again on the same issue.

I'm sort of reluctant to ring them to further follow up so would appreciate some feedback .............

Have you had the same issue, and has one round of resetting sorted it? Any other observations?

Postby **beavis** » Sat Apr 16, 2016 10:01 pm

I'd be happy to try it out for you and report back.
Just hand me a set of keys.

davekmoore · Postby **davekmoore** » Sat Apr 16, 2016 10:17 pm

Keys in transit.

Roadrunner · Postby **Roadrunner** » Wed Apr 20, 2016 9:51 am

Not myself, but have had a friends ND have it come on and that was just on freeway driving.
Was reset by the dealer and has not come back on as far as I am aware.
I know several ND owners who have had a false warnings and it eventually comes back on after being reset.

Are there instructions on how to reset the warning ourselves?

I'm also intrigued by how the TPMS is set/works.
Are the tyres inflated to a certain PSI and the TPMS is told "This is Normal Pressure" and alarms when say 4psi less pressure is detected?

Where I am going with this is, would it be possible to deflate the tyres to say 20psi and tell the TPMS that this is "Normal". Then inflate the tyres up.
This way the warning will only come on when you genuinely have a tyre going down (below 20psi), not when pressures change slightly due to heat?

Or is that not how this works at all? :oops:

chops · Postby **chops** » Wed Apr 20, 2016 10:42 am

if you hold the button down for 5 seconds it will reset. This allows you to change tyre pressures and the system will 'learn' the new pressure. Not really an MX5 application but this is traditionally useful when towing in say a loaded CX5 were you may want to run higher pressures. I don't know the specific level of change required to bring the warning on but it would be quite small as I have seen them on cars measuring within 1 pound across all 4 tyres

Roadrunner · Postby **Roadrunner** » Wed Apr 20, 2016 5:18 pm

Hmm so my theory above 'may' work then? And then you'll only have the warning come on when your truly having a tyre loosing pressure/puncture, not just fluctuating, or will it warn of "over pressure"?

I haven't had the pressure warning personally but when I do, I might try this out.

davekmoore · Postby **davekmoore** » Wed Apr 20, 2016 6:20 pm

chops wrote:if you hold the button down for 5 seconds it will reset. This allows you to change tyre pressures and the system will 'learn' the new pressure.

Correct. But don't reset without first checking all tyres are at correct pressures otherwise the system will potentially normalise incorrect pressures.
The system uses the ABS rings to sense how often the wheels are turning in order to recognise one corner turning faster than it was at the last reset. It ignores short-term variations such as one front wheel turning more often on corners or one rear wheel spinning.

hks_kansei · Postby **hks_kansei** » Thu Apr 21, 2016 3:33 pm

is it just a "low pressure" warning, or does it also warn that pressure is too high?

I know that hard driving heats the tyres, which from memory also brings the pressure up a little.

I assume that the threshold isn't able to be changed either? (ie: tell it to only whinge when pressure drops by 10psi)

it sounds like the whole "blown bulb" warning things that seem to just constantly tell you a bulb is blown.

davekmoore · Postby **davekmoore** » Thu Apr 21, 2016 5:53 pm

It will not warn if all four pressures have increased equally, for instance in spirited driving.

However, it might notice if one ABS ring is reporting more rotations due to one tyre not getting as much temp into it, thus having a smaller rolling radius. An extreme example would possibly be the front left wheel on a light braking anti-clockwise track.

project.r.racing · Postby **project.r.racing** » Fri Apr 22, 2016 8:16 am

In a effort to save grams. Mazda still add this useless feature?

Odd · Postby **Odd** » Fri Apr 22, 2016 10:19 am

It is in my wife's CX5.....
light came on a couple of weeks ago....she had no idea what it was....
I told her it was tyre pressure sensor.....but she argued it was something else after checking handbook
Checked tyres at servo....no problem I could see, so reset it
Good idea in principal....but I'll bet those who most need it....don't know what it is if light comes on

elbekay · Postby **elbekay** » Fri Apr 22, 2016 6:55 pm

Mine (ND 1.5 GT) has gone off twice during highway driving in 5,000 kms. Pulled into a servo and checked the pressures, everything was fine; so it was two false alarms.

davekmoore · Postby **davekmoore** » Fri Apr 22, 2016 7:27 pm

Perhaps it's just as useful as the gear change indicator?

Wonder how much weight Mazda would save by deleting the TPM switch and all those unneccessary pixels?

elbekay · Postby **elbekay** » Sat Apr 23, 2016 8:05 am

I'd much prefer if they'd used the gear change indicator to show speed instead......

Mr Morlock · Postby **Mr Morlock** » Sat Apr 23, 2016 4:39 pm

so has the ND got a gear indicator? If it has I reckon that is a great feature. The 6 speed on the NB with the spring action can be a bit tricky and I occasionally get caught out. Someone not familiar with a car would benefit from an indicator. I drove an unfamiliar manual as a hire car and I found the gear indicator really useful. The TPS thing is also good in principle because I reckon many drivers rarely check their pressures. It would be fun to check 100 cars and see how the pressures vary and prepared to bet that there would be some alarming results.