Aah tyre pressure warning light

[olliesgrandad]

Well this morning it was below zero under my carport and when my car was started the tyre pressure warning light was on. Well I looked everywhere including the handbook and nowhere did it say how to reset the thing. Fortunately after driving for half an hour the light disappeared. Why isn't there information on resetting the light when the cold wat

Weather  certainly the issue? 

[Britprius]

20 minutes ago, olliesgrandad said:

Well this morning it was below zero under my carport and when my car was started the tyre pressure warning light was on. Well I looked everywhere including the handbook and nowhere did it say how to reset the thing. Fortunately after driving for half an hour the light disappeared. Why isn't there information on resetting the light when the cold wat

Weather  certainly the issue? 

The tyre pressures should be set in the monitoring system while the tyres are cold and at the correct pressures "cold". So it is likely that a tyre is low on pressure even though it is higher than the warning trigger limit when warm. Warm pressures should be higher than the pressures shown on the door jam lable.

John.

[ColinBarber]

Your tyres are probably a bit low, combined with the cold weather than has dropped the pressure by 2 or 3 deg compared to a 'cold' 20 deg in the summer. Set your pressures to the correct cold temp and recalibrate the system.

[NemesisUK]

14 hours ago, olliesgrandad said:

Well I looked everywhere including the handbook and nowhere did it say how to reset the thing.

This is for my RC but I believe the button location is similar for most models? It is very awkward to access ...

How to initialise the tire pressure warning system

• Park the vehicle in a safe place and turn the power switch off.
• Initialisation cannot be performed while the vehicle is moving.
• Adjust the tire inflation pressure to the specified cold tire inflation pressure level. 
• Make sure to adjust the tire pressure to the specified cold tire inflation pressure level. The tire pressure warning system will operate based on this pressure level.
• Turn the power switch to ON mode.
• Press and hold the tire pressure warning reset switch until the tire pressure warning light blinks slowly 3 times.
• Wait for a few minutes with the power switch in ON mode and then turn the power switch off.

[Britprius]

As the very useful post above, but note in two places it stipulates the pressures, and setting of the system should be done "cold".

John.

[Upex]

My tpms warns of check system when cold, Battery on one is on last legs, so when cold, fails. When warm, returns back to life. Cycled about 20 times lol.

Not even been out to the Lexus with the snow, its 14 inch deep here, so took the dirt bike to work yesterday, was fun bar the white outs, one of which saw me nearly hit someone house having rode right up their garden. but was pure ice on way home, so stayed indoors today.

Drive safe folks

[olliesgrandad]

Well a bit warmer today so checked and pumped the tyres to recommended pressure. Warning light still on. Drove car a couple of hundred yards and it reset. 

[Britprius]

On 3/3/2018 at 11:14 PM, olliesgrandad said:

Well a bit warmer today so checked and pumped the tyres to recommended pressure. Warning light still on. Drove car a couple of hundred yards and it reset. 

The pressure monitors in the tyres do not continuously transmit the information just every few minutes. This is to save Battery life in the monitors. If they transmitted continuously the batteries would not last long, and this is the reason for the delay.

John.

[Ala Larj]

How cold is cold? 

[Britprius]

1 hour ago, Ala Larj said:

How cold is cold? 

Cold pressures are considered to be the temperatures of the tyres after standing for 2 hours minimum without being driven.

John.

[Ala Larj]

But that could be a huge difference in temperature between summer and winter!

[Britprius]

37 minutes ago, Ala Larj said:

But that could be a huge difference in temperature between summer and winter!

I agree, but the difference is not as large as the variation when checking tyres hot as both the speed driven, the duration, load carried, ambient temperature, and possible under or over inflation in one or more tyres would affect the readings

[NemesisUK]

The important measurement is pressure, not temperature but as the pressure changes with temperature the only way to correctly measure the pressure of air in the tyre that air must be at the same temperature as the atmosphere surrounding it.

So, it doesn't matter what the ambient temperature is, just so long as the air in the tyre is at the same temperature.

Manufacturers factor in the the heat generated (above ambient) in the tyre by the amount of sidewall movement allowed by the inflation pressure. 

 

[Ala Larj]

11 minutes ago, NemesisUK said:

The important measurement is pressure, not temperature but as the pressure changes with temperature the only way to correctly measure the pressure of air in the tyre that air must be at the same temperature as the atmosphere surrounding it.

So, it doesn't matter what the ambient temperature is, just so long as the air in the tyre is at the same temperature.

Manufacturers factor in the the heat generated (above ambient) in the tyre by the amount of sidewall movement allowed by the inflation pressure. 

 

That makes sense, thanks.

[Vlady]

On ‎2‎/‎28‎/‎2018 at 1:38 PM, NemesisUK said:

This is for my RC but I believe the button location is similar for most models? It is very awkward to access ...

How to initialise the tire pressure warning system

• Park the vehicle in a safe place and turn the power switch off.
• Initialisation cannot be performed while the vehicle is moving.
• Adjust the tire inflation pressure to the specified cold tire inflation pressure level. 
• Make sure to adjust the tire pressure to the specified cold tire inflation pressure level. The tire pressure warning system will operate based on this pressure level.
• Turn the power switch to ON mode.
• Press and hold the tire pressure warning reset switch until the tire pressure warning light blinks slowly 3 times.
• Wait for a few minutes with the power switch in ON mode and then turn the power switch off.

This is what manual says but I am either blind or stupid but I can't find this button! 

I have similar issue, the light is on on the dashboard, I checked the tire pressures and made sure they are to the manufacture requirements (tire were cold) but I do not know how to reset the TPM, I drove the car after that and it didn't reset itself, what am I doing wrong?

Can it be that the garage that sold me the car and who changed the rear tires didn't do something right like ID these sensors?

Thanks.

 

[Ten Ninety]

28 minutes ago, Vlady said:

This is what manual says but I am either blind or stupid but I can't find this button! 

I have similar issue, the light is on on the dashboard, I checked the tire pressures and made sure they are to the manufacture requirements (tire were cold) but I do not know how to reset the TPM, I drove the car after that and it didn't reset itself, what am I doing wrong?

Can it be that the garage that sold me the car and who changed the rear tires didn't do something right like ID these sensors?

Thanks.

 

Your inability to find this silly button does not make you blind or stupid. It's very hard to access. You might want to put the seat all the way back so you can get properly inverted with your head right in the footwell. If you can manage to look up from there, it's on the underside of the dash.

[Vlady]

1 hour ago, Ten Ninety said:

Your inability to find this silly button does not make you blind or stupid. It's very hard to access. You might want to put the seat all the way back so you can get properly inverted with your head right in the footwell. If you can manage to look up from there, it's on the underside of the dash.

Thanks, I will have a look again tomorrow but I am pretty sure it's not there but as you say of it's hidden that well I will give it another try!
Why would you hide it that far, why not make an option within interface like many Germans do? I guess it is easier just press the button if you can find it in 1st place! lol! 🙂

[KayCee]

just get a shaving mirror put it in footwell and you will see it straight away

 

[Vlady]

9 hours ago, KayCee said:

just get a shaving mirror put it in footwell and you will see it straight away

 

Founded it, oh God, why would you put it there! Still need to reset it as tires are warm now, will do in a morning or later tonight!

Thanks everyone.

[Vlady]

On ‎2‎/‎28‎/‎2018 at 1:38 PM, NemesisUK said:

This is for my RC but I believe the button location is similar for most models? It is very awkward to access ...

How to initialise the tire pressure warning system

• Park the vehicle in a safe place and turn the power switch off.
• Initialisation cannot be performed while the vehicle is moving.
• Adjust the tire inflation pressure to the specified cold tire inflation pressure level. 
• Make sure to adjust the tire pressure to the specified cold tire inflation pressure level. The tire pressure warning system will operate based on this pressure level.
• Turn the power switch to ON mode.
• Press and hold the tire pressure warning reset switch until the tire pressure warning light blinks slowly 3 times.
• Wait for a few minutes with the power switch in ON mode and then turn the power switch off.

Well, I found the button but pressing it doesn't change anything and the light is still on! 

Do I follow instructions right? When it says switch the power ON, does it mean start the car like brake pedal pressed and push the switch button on? 

Anyway I tried both ways (starting the car and just pressing switch ON) and it didn't work, I mean the light is flushing initially for a while, then flushing stops, I push the reset button and the light doesn't flush 3 times as needed and just stays on. Do I really need to go to Lexus? Did anyone had similar issue?

Thanks.

[KayCee]

  sounds like you have a dud Battery if you have followed instructions

Ni do not start engine just press button no foot on brake

[Vlady]

13 minutes ago, KayCee said:

  sounds like you have a dud battery if you have followed instructions

Ni do not start engine just press button no foot on brake

Hi KayCee, thanks for replying, when you say Battery you mean sensor batteries, right? Not the main car Hybrid Battery!

I have tried by just pressing the switch on button (with no foot on brake) and my dash board doesn't even show anything (like low tire pressure warning) so I press reset button nothing happens, I hold for different amount of time (from 3sec to 30!) and nothing! 

May be it is a sensors batteries. Do you need to remove the tire to change the sensors or the batteries? Sounds like a Lexus job, it's probably need some sort of coding after that.

Thanks KayCee.

[Vlady]

23 minutes ago, KayCee said:

 

Ni do not start engine just press button no foot on brake

I will give it a go one more time on my lunch.

[NemesisUK]

1 hour ago, Vlady said:

May be it is a sensors batteries. Do you need to remove the tire to change the sensors or the batteries? Sounds like a Lexus job, it's probably need some sort of coding after that.

The batteries can be replaced but it would be a DIY job as they are not designed for maintenance, Lexus will simply replace the complete sensor(s). IIRC they are ~£80 each

The tyres will need to be removed and the new sensor will need to be registered to the car's system.

There is a thread on the forum detailing the DIY replacement of the Battery in the sensor. Battery is cheap less than £5 but requires soldering in place and re-potting to seal it in. The tyre will still need removing and re balancing in all cases.

[NemesisUK]

This is the thread detailing Battery replacement