TPMS Receiver or Computer?

Interesting question... I currently have a TPMS light that goes on only when I get up to freeways speeds for longer than 20 minutes and then goes away after a couple days of driving around town. I also am curious as to how the TPMS processing works and if it measures all four sensors in a dedicated way, or just polls them periodically. I bet @Elektroingenieur could explain this...

I was thinking I simply have one failing TPMS sensor, but maybe the way the system works it's more than that?

 

As Toyota explains in the Repair Manual (more info), there is only one receiver:

A tire pressure warning valve and transmitter is equipped with a tire pressure sensor and is installed in each tire wheel assembly. The sensor measures the tire pressure. The measured value and transmitter ID are transmitted to the tire pressure warning antenna and receiver on the body as radio waves, and then sent to the tire pressure warning ECU from the tire pressure warning antenna and receiver. If the transmitter ID has already been registered, the ECU compares the measured air pressure value with the standard value. When the value is less than the standard value registered in the tire pressure warning ECU, the warning light on the combination meter turns on.​

The transmitters don’t operate continuously. The exact conditions aren’t described, but the test report (PDF) submitted for FCC authorization describes a ”rotating mode,” with transmissions every 64 seconds, and a “stationary mode,” with transmissions every 320 seconds, among others.

Without information Toyota hasn’t published about how the system works, it’s difficult to say for sure what might be happening, but it could be that the heating from sustained freeway driving causes the pressure to increase enough, relative to the standard value—which might have been registered when the tires were cold, underinflated, or both—that the system warns you of overinflation. When the TPMS warning light is on, have you checked the reported tire pressures or for stored DTCs?

 

What sensors did you use? Have you driven the car for a few miles?- sometimes makes a difference on some cars.

The Gen2 uses a single receiver. Can't say that I have ever seen a single "dead channel" on this type of system. (my experience has most ecu faults preventing ID programming from going through)

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These are the sensors I used. Worked fine.

 

Yes, I forgot to mention these are brand new tires that I decided to take a chance on not replacing the TPMS sensors on when they were intalled and TPMS came on soon as that was done after first 20 minutes of freeway driving. On the bright side they were 2012 wheels with original TPMS sensors and have had no issue around town for 4 months & 4K miles. Only when I travel long distances.

 

And pumping up the tires to 48 lb up front and 43 or so in the rear seems like that would be getting up into the 50-some odd pounds heated or not cold. I used the Pacific brand sensors that Toyota sent with the car they make the center caps for your wheels It's printed on the back of the center caps It's also printed with a green logo directly on the TPMS sensor in the wheel ours are green they make some red ones I don't know the difference if it's frequency or what I bought the same green. I'm not whipped out the tec stream to attempt to register them I was going to take it by my friend's tire store just haven't got around to it. But what I have noticed is that with the new sensors installed in the wheels and mounted to the car the TPMS sensor light now flash is about eight times or two times per wheel It seems to me it's sensing that the sensors are in fact there and are somewhat working but are not registered when the ECU determines this it puts the TPMS light from flashing to solid. Now if while driving with the TPMS light solid. If a tire goes down the TPMS light will start to flash kind of like it would if the light was off so something seems to be happening. I'll try and get by this week and have my buddy run as wand around the car and put the light off and then I guess I'll be able to set my tire pressure with the button and all of that but I thought it was interesting that the sensors seem to be being sensed and somewhat working even with the TPMS light on.

 

With Techstream you can see realtime tire pressure and temp but not location. The seven digit "Registered ID Code" has to be identical to the ID code on the sensor. When changing sensors the vehicle stored IDs have to be changed.



In this case ID2 was not reporting properly. If you have an Autel tpms scanner, you can individual rf scan each tire to determine where each ID is currently located. Without the $150-$250 Autel, you either change them all or you reduce the pressure in each tire one at a time while watching Techstream. In my case ID2 was on the rear passenger tire.

To program new sensors with Techstream, you go to the Utility item and follow directions. However the new sensor won't be read by the vehicle until it is installed and is driven above 20 mph. At that point the TPMS light will clear without needing an under dash reset.

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Finally, for those of you with a set of winter tires and wheels, some sensors such as the "Autel TPMS Sensor MX-Sensor" can be programmed with the ID codes from your summer wheels. As a result, no tpms registration is needed when swapping sets. The Autel MX sensors do require an Autel scanner although a $54 "Autel MaxiTPMS PAD" version is available for Windows PC based operation. This unit does not rf scan sensors on the car and only programs their MX sensors.

https://www.ebay.com/itm/364074183648
The $28 option is just one sensor.

 

Have you considered side-stepping the issue, ie: just fugedaboutit.

When I got snow tires on separate rims for our 2010, over 12 years back now, the dealership mechanic asked if I wanted TPMS sensors, while shaking his head...

I didn't need convincing, but it was nice to see I wasn't alone in my sentiment.

They're great, can save your bacon, but Toyota's iteration sucks. On the plus side, if you need a hobby, getting Toyota's system up and running will keep you busy.

 

For $43 plus tax I would change them all. New IDs for each. Almost has to be a sensor but I suppose it could be a position on the car with weak rf due to old batteries and the body.

There is just one antenna in the right rear.

Short of changing them all, I would do the reduced pressure test on each tire to id the physical sensor that is not reporting. Then move that tire to the opposite end or closer to the antenna.

My experience when tests don't make sense and I am familiar with the logic and wiring; generally I have created a false negative on one of the steps. This leads to assumptions that are not correct.