Tyre Pressure Sensors

[Penfold72]

Hi

Set off for work this morning, and the tyre pressure sensor light lit up. Stopped car, but all tyres looked OK, and I put it down to the low temps this morning, after the really high temps we have had. (7 degree where I live).

Car drove normally, but I noticed when I got on the motorway, the light went off, although message on media unit was still there. I assumed that these systems, once the Warning was triggered it stayed on until reset.  Is the toyota system dynamic, and if there was a lower pressure, once tyres got to temp the pressure came up to normal, and sensor detected this???  I will check the pressures when I get home.  Also could be a sensor glitch as well?  I've already had 2 of these replaced!!

Anyone any other ideas? I suppose the pressures could be borderline, and the cold morning triggered the warning.  I must admit im not one to religiously check tyre pressures every week 😏

 

[Chrisg99]

25 minutes ago, Penfold72 said:

Hi

Set off for work this morning, and the tyre pressure sensor light lit up. Stopped car, but all tyres looked OK, and I put it down to the low temps this morning, after the really high temps we have had. (7 degree where I live).

Car drove normally, but I noticed when I got on the motorway, the light went off, although message on media unit was still there. I assumed that these systems, once the Warning was triggered it stayed on until reset.  Is the toyota system dynamic, and if there was a lower pressure, once tyres got to temp the pressure came up to normal, and sensor detected this???  I will check the pressures when I get home.  Also could be a sensor glitch as well?  I've already had 2 of these replaced!!

Anyone any other ideas? I suppose the pressures could be borderline, and the cold morning triggered the warning.  I must admit im not one to religiously check tyre pressures every week 😏

 

I think it has been mentioned before. One way is to inflate tyres to say 2 psi below prescribed pressure, reset TPMS inflate tyres to correct pressure. If the light comes on then you know the tyre or tyres have dropped 2 PSI.

[Penfold72]

Good idea.

I will do this when I get home in a couple of hours.

[philip42h]

The Toyota TPWS isn't terribly smart - it relies on the system being Reset when the tyres are at the correct pressure and will then warn when the pressure drops significantly below the set level (rather than at or just below the set level). If the dealer set it up correctly at PDI, the owner will probably never have to worry about the system at all.

But, several folk have found that the original setting was significantly higher than the proscribed 'correct' level resulting in warnings being issued when the tyres are at a perfectly acceptable pressure.

The 'solution' is to carefully inflate all four tyres to the correct pressure and then Reset the TPMS system. It will then work as it should ...

(That has worked for me. It's very disconcerting getting an incorrect tyre pressure warning.)

[Penfold72]

Checked the pressures after an hour or so of getting home. They were all down,  at 30psi, 1 at 29psi. Pumped all back to 33 and reset system. Checked the 8nfo I got when 2 sensors replaced, and all were setup to 33. Likely normal drops as I haven't checked them since sensors replaced back in April, exacerbated by the colder temps this morning. See how it goes. Yes, I hate it when I get these issues when driving, particularly if I'm unable to stop to check things out. Actually read manual, and it does, say if tyres pumped to correct values light should go out on its own. 

[UncleZen]

What type of tpms does the chr have? Is it the type that detects differences in wheel rotation speed? Or the type that actually has a sensor in the wheel/tyre? Or is there a 3rd way?

[Penfold72]

They have a sensor in the valve, and something attached inside the wheel. I was a bit disappointed that the C-HR didn't have a display telling you the pressures though. My previous car did and it was pretty useful info to have 

[Starensis]

Best way is to inflate to 28psi, reset system, then inflate to 34psi. You know then; if light comes on, they’re below 28psi and you may have a slow puncture.

[UncleZen]

If there's a sensor in the valve, does I have a Battery? And if so, how long would it last?

[Starensis]

Yes it does. It’s a sealed unit so not capable of being changed. They last around 8 years I believe, probably longer.

[Penfold72]

I've heard there is a secret menu on the C-HR. No idea how to access, but does anyone know if this gives the actual pressures. The sensors look the same as on my previous car, so I would assume they store or read the actual pressures.

[UncleZen]

So, presumably, at some point in the future the battery(s) will go flat and will need the tyre removed to replace it/them. I would expect all 4 to fail at roughly the same time, and ideally coincide that with replacing tyres. Presumably replacement valves can be got from Toyota? 

[philip42h]

1 minute ago, UncleZen said:

So, presumably, at some point in the future the battery(s) will go flat and will need the tyre removed to replace it/them. I would expect all 4 to fail at roughly the same time, and ideally coincide that with replacing tyres. Presumably replacement valves can be got from Toyota? 

Google reports various estimates of the service life of TPMS batteries but somewhere between 5 and 12 years. I part ex'd my previous RAV4 after 7 years - still on the original TPMS batteries. Quite how long are you planning on keeping this car Uncle Zen?

And, yes, Toyota will supply and fit the necessary replacement valves and do the necessary work to code them into the car's computer etc.. And, no, there's not a chance that they will all fail at the same time nor coincident with needing new tyres - you'd never get that lucky ... 😉

[Penfold72]

12 hours ago, philip42h said:

Google reports various estimates of the service life of TPMS batteries but somewhere between 5 and 12 years. I part ex'd my previous RAV4 after 7 years - still on the original TPMS batteries. Quite how long are you planning on keeping this car Uncle Zen?

And, yes, Toyota will supply and fit the necessary replacement valves and do the necessary work to code them into the car's computer etc.. And, no, there's not a chance that they will all fail at the same time nor coincident with needing new tyres - you'd never get that lucky ... 😉

I had 2 fail at the same time, a few days after buying the car....  Toyota sorted it all quickly though.  They did say they were very surprised.

[UncleZen]

On 9/26/2023 at 8:12 PM, philip42h said:

Toyota will supply and fit the necessary replacement valves and do the necessary work to code them into the car's computer etc.

Just planning ahead, you never know.

So it can't be done at my local tyre shop then?

[philip42h]

17 minutes ago, UncleZen said:

Just planning ahead, you never know.

So it can't be done at my local tyre shop then?

That would depend on quite how 'smart' your local tyre shop is. Most if not all modern cars have some sort of TPMS system. If it is done with pressure sensing valves that 'send' data to the ECU, the ECU needs to know about the specific valves fitted to your car - so their identities need to be coded into the ECU. One might hope that a 21st century tyre shop would be able to do this but ... 😉