At what pressure does it trigger the TPMS?

[cool_beans00]

It looked like my car tires were low on tire from the dealership. I went to measure them the other day and it was 24PSI all around. Well below the recommended pressure of 32PSI. I was curious why The TPMS didn't tell.

anyone know why?

thanks!

[rningonfumes]

It's less the pressure and more if there is a difference between any of the four.

The TPMS we have is crude. If it sees all four tires as being at 25psi (+/- 2) the computer thinks everything is fine and does not light the lower tire light.

Also the other reason is that the trigger point is probably set very low.

[SailDesign]

I had heard that the trigger pressure was around 17 psi - basically the point at which it's not just a question of wear, but of safety. TPMS does NOT mean you shouldn't check 'em by eye just as often to keep them sweet.

[CTScott]

I had heard that the trigger pressure was around 17 psi - basically the point at which it's not just a question of wear, but of safety. TPMS does NOT mean you shouldn't check 'em by eye just as often to keep them sweet.

It's somewhere around there for the low threshold and around 70 for the high threshold. Also, it triggers if any tire deflates more than about 6psi in 30 seconds.

[SailDesign]

It's somewhere around there for the low threshold and around 70 for the high threshold. Also, it triggers if any tire deflates more than about 6psi in 30 seconds.

That is good to know. So it basically means "if you see the light, pull over and check NOW!" :smile:

[ilikerice]

wait.. i know on lexus tpws you can set the light to whatever pressure you want. for example, i could set my sensor for 40psi.. when the psi drops to around 30ish the light would come on. i know with the techstream at lexus, you can see where the sensors are set at and thier thresholds. i dont remember exactly but i thought that if your sensors were set at 32 psi. the threshold is 6-8psi up or down... i havent checked, but does the yaris have a "set" button somewhere for the light on the yaris? i know some ES350 did not have that button. but other models did

[CTScott]

wait.. i know on lexus tpws you can set the light to whatever pressure you want. for example, i could set my sensor for 40psi.. when the psi drops to around 30ish the light would come on. i know with the techstream at lexus, you can see where the sensors are set at and thier thresholds. i dont remember exactly but i thought that if your sensors were set at 32 psi. the threshold is 6-8psi up or down... i havent checked, but does the yaris have a "set" button somewhere for the light on the yaris? i know some ES350 did not have that button. but other models did

The Yaris doesn't have a set button. It's TPWS system is quite primitive. It is the only ECU on the Yaris that is not CAN (it is ISO9141) and has no communication interface to the ECM. It is actually a completely stand-alone system and even its indicator light is an isolated circuit in the cluster.

[ilikerice]

thanks for the clearing that up for me.. very interesting..