tpms question

[hankd]

hi folks,
i'm trying to get the tpms light to go off on my truck and i do not want to bypass this functionality.

the tpms light was flashing, i went to a local tire shop and they replaced 3 of my sensors. now the light is solid. this means that the truck is getting a low tire pressure reading from somewhere. put 500km on the vehicle. i am taking the vehicle in to get looked at by the same tire shop and potentially have the other two sensors replaced this week to see if that will fix things up. is it possible one of my existing sensors is half working and just sending a bad signal to the truck? all of my tires, including the spare, are at 32. i believe threshold for the light is 27.

i had my ecu replaced last year because i got my floor wet. truck had to go to toyota to have the keys programmed to it. i am just wondering if this could somehow be affecting my tpms readings. is there ever a case where i need toyota involved? people have mentioned needing the dealer or techstream in other threads, but it was only mentioned vaguely.

i can't remember when the tpms light started acting up, or if it started behaving in a certain way when i had the ecu replaced.

my understanding of the light is as follows:

* if the truck doesn't read all 5 sensors, tpms light will blink
* if the truck can't read all 5 sensors, but any working sensor sends a low pressure signal, the light will stay steady. i had a flat tire which made this happen; plugged and refilled the tire and the light went back to blinking again. so i drew my own conslusions.
* if truck sees all 5 sensors, and no sensor reports <27, no light.

thanks!

 

[y=mx+b]

This might sound like a dumb solution, but have you tried unplugging the negative battery cable and letting it sit for a bit? I've had my TMPS light flashing for 6-8ish months, and recently I unhooked my negative battery cable while looking at something. I noticed the light isn't back on or flashing now after 200ish miles. Not sure if its from that incident exactly, but I haven't done anything tire related and the light isn't flashing anymore.

Worst case scenario, you just unplugged the cable and lost the radio channels. Best case, computer resets and things work out.

 

[knarfwhite]

I think the TPMS system is problematic and that is why most bypass it. I don't see the point of a system that doesn't give you the pressure or tell you which tire is low.

 

[Syr4RinNC]

Agree with above. Question is how much time and money do you want to put into it. I think anything is possible - that the issue with go away with replacing tpms, that the installer used the wrong frequency/ signal in the new monitors, or that your computer is getting bad signals/ is the problem

I think a Toyota dealer is more likely to get to the bottom of it at a premium price.

Good luck, but hopefully it’s premature if replacing the other two solves your issue

 

[hankd]

i'm in this deep so i'll replace the other 2 sensors for 100 bucks and if that doesn't solve it i'll walk away from it and do the bypass.

 

[hankd]

So if I end up with 5 aftermarket sensors from this tire shop, I don’t need a trip to the dealer due to my non-original ecu for some reason, can I verify that?

Do they try and clone the new tpms sensors from an existing sensor and now my truck has 5 tpms sensors programmed to my old ecu?

How do the tpms sensors authenticate Or handshake to the vehicle? I’m unclear on how the whole process works.

 

[Syr4RinNC]

I believe they have a certain frequency they work at and the ecu receives it - analogous to Bluetooth. The ecu should be programmed to receive it. There’s weird things that can happen but if you got an ecu for the 4Runner ideally it should work

Other makes and models use different radio frequencies for their tpms

 

[ecally]

If the light flashes, but goes solid after a minute, then a sensor somewhere is bad. If it keeps flashing you have a low tire. If the system is working correctly that is. From your description, sounds like there is still a bad sensor.

 

[hankd]

If the light flashes, but goes solid after a minute, then a sensor somewhere is bad. If it keeps flashing you have a low tire. If the system is working correctly that is. From your description, sounds like there is still a bad sensor.

i've heard the thing about the light flashing then going steady, however mine would just keep flashing as long as the vehicle was running.

i believe if it stays steady, it means low pressure. that's from my experience when the system worked, and also from the manual.

 

[m85476585]

Pretty much all tire shops have a tool that will program new TPMS sensors into the car's ECU. They are universal and work with most cars. They should sell you compatible aftermarket sensors that will operate on the same frequency. Some can be cloned to match the IDs of the ones you have and some can't, but if not they can just program the new IDs into the car.

Let me know if you figure it out. My light has been flashing for the past couple years. It is ridiculous how non-user friendly this system is.

 

[hankd]

i had the remaining two tpms sensors replaced today (so all 5 replaced this week). the tire shop that did it still couldn't get the light off because their programmer tool couldn't communicate with the vehicle (my ecu came from ebay so probably had the old vehicle's tpms info in it although i did have the dealer program the keys). thought i was sol, but i took it back to the shop that did my timing belt job a few weeks ago and they were able to program them and the light is now off.