TPMS fault?

[LandCruiser]

I usually check the pressures in my tires once a week, or before a long road trip and keep them aired up 37-38 cold.

One of my tires recently had a nail in it and was 29 cold, the others were 35.5-36. The TPMS didn't register.

Dealer seemed puzzled and bled the tire down some more until the light went off.

Am I missing something?

btw

All new model year 2008 light vehicles shall have a TPMS fitted which is capable of detecting when one or more of the vehicle's tires, up to all four tires, is 25 percent or more below the manufacturer's recommended inflation pressure (placard pressure) or a minimum activation pressure specified in the standard, whichever is higher. The system should be able to detect when one or more of the vehicles tires are 25% or more below the recommended inflation pressure.

Am I just at the threshold?

 

[eddiebx]

I usually check the pressures in my tires once a week, or before a long road trip and keep them aired up 37-38 cold.

One of my tires recently had a nail in it and was 29 cold, the others were 35.5-36. The TPMS didn't register.

Dealer seemed puzzled and bled the tire down some more until the light went off.

Am I missing something?

btw

All new model year 2008 light vehicles shall have a TPMS fitted which is capable of detecting when one or more of the vehicle's tires, up to all four tires, is 25 percent or more below the manufacturer's recommended inflation pressure (placard pressure) or a minimum activation pressure specified in the standard, whichever is higher. The system should be able to detect when one or more of the vehicles tires are 25% or more below the recommended inflation pressure.

Am I just at the threshold?

I forgot where I read it, but I think the threshold is ~26-27psi? So, if it's a slow leak it might take a while for the TPMS to detect the low air pressure. As long as the TPMS light eventually came on after they bled it down I wouldn't worry about it too much. It's probably normal.

 

[CrazyNorwegian]

Federal law requires the TPMS light is programed to alert you when the pressure is 25% below recommended pressure.....not 25% lower then what you currently have in your other tires. So if your door placard says 32psi then the tpms light will go off at about 24psi. Many manufactures tend to program the light to come on closer to a 15% drop below recommended pressure, which is around 27psi. The sensors also have an accuracy of +/- 2psi. Most Toyota's have a button to set the threshold to a higher level but I haven't found it yet on the 4runner, nor have I really looked.

 

[Froggy]

Federal law requires the TPMS light is programed to alert you when the pressure is 25% below recommended pressure.....not 25% lower then what you currently have in your other tires. So if your door placard says 32psi then the tpms light will go off at about 24psi. . . .

Yep. Second grade arithmetic & simple logic.

 

[Canazes9]

Also keep in mind that different tires will affect the TPMS sensors differently, even more so if you change from P Metric to LT, different ratings (C, D, E, etc) and different tread types (most OR LT tires have significantly thicker tread blocks). When I switched out the factory 265/70r16 Dunlops to 265/75r16 Mickey Thompson MTZ's on my '12 Tacoma, the tech inflated them to 32psi as on the sticker on the door - the TPMS light wouldn't go out. The shop owner put 40 psi in them and the light went out. I reset the Tacoma sensor myself - it's a little button directly under the steering column. Not sure on the 4Runner, I think it's the same, not positive. I'm sure you can find what you are looking for in the owners manual....

David

 

[buchaja]

Mine tripped at 29psi. At that time I was keeping them at 32, but have been doing 35 now. I'm pretty bad about checking them, so I don't know if all of them are that sensitive or not.

 

[eddiebx]

Also keep in mind that different tires will affect the TPMS sensors differently, even more so if you change from P Metric to LT, different ratings (C, D, E, etc) and different tread types (most OR LT tires have significantly thicker tread blocks). When I switched out the factory 265/70r16 Dunlops to 265/75r16 Mickey Thompson MTZ's on my '12 Tacoma, the tech inflated them to 32psi as on the sticker on the door - the TPMS light wouldn't go out. The shop owner put 40 psi in them and the light went out. I reset the Tacoma sensor myself - it's a little button directly under the steering column. Not sure on the 4Runner, I think it's the same, not positive. I'm sure you can find what you are looking for in the owners manual....

David

I know exactly the system you are talking about, but I don't think our 4runner uses this type anymore. There's no option to initialize the TPMS base value because it only trips at a set tire pressure value. My old car had the same exact button as your Taco.

When I look back and think about it, it is a bit of pain because if you disconnect the battery you lose the initialization, which could lead to incorrect base values (upon reconnecting the battery); thus, erroneous TPMS lights. My only guess is, it's too finicky and high maintenance for the soccer moms driving our 5th gens to understand, lol. But they sure do come in handy for those of us that like to run tire pressures different from stock!