How does TPMS work?

Does anyone know for sure how this works? I’d like to know if the sensors on the wheels “report” to the computer on board the truck or does the computer on board the truck “poll” the sensors. If the sensors “report” than I wonder if it would be possible to add a sensor to the spare by cloning a number already in use by one of the other wheels. If the computer just sits there waiting to hear from a tire sensor when something is wrong than it wouldn’t matter if the same ID number was used by multiple wheels, right? I do a five tire rotation and the goal here would be to add a sensor to my spare tire.

 

Sorry can't answer , but seems like a lot of work for not much return.

 

No computer, it's Tire Pressure Magic System.

 

Serious note, your spare should already have a sensor. When I got new tires they had to reprogram all 4 plus the spare.

 

There's a sensor on the valve stem that reads pressure and transmits it to the computer, each sensor has a unique code.

I don't know if you can add one though.

 

The sensor in the spare was stopped in 2009 (2008 was the last model year to have it).

 

X2. Depending on the year, all 5 tires should have sensors already.

Edit: Of course; if you don't, I believe that the truck has room in its memory for 5 sensors, so programming in a fifth should be possible even if yours didn't have one from the factory.

 

Didn't know that, however both the 09's I have owned had the spare tire with a sensor. Maybe 2009 was the last year?

 

And other Toyota models are different too. My '14 Tacoma doesn't have a sensor in the spare. My '12 RAV4 does.

 

My '09 doesn't have TPMS in the spare

 

My 2012 has one in the spare. I couldn't figure out why my TPMS light was illuminated when all four tires were at the correct pressure, then it dawned on me...the spare was at 22psi.

 

Would this mean there is a battery in the sensor? If so, any idea how long they will last?

 

Yes, there is a battery.
The battery last between 5 and 8 years.

 

It's a government tracking device.

 

just dont even rely on the TPMS.... you should check tire pressures regularly anyways.

 

If you have a dealer check out the TPMS with their reader, you can see that each tire sends out info on tire pressure and tire temperature. Unfortunately, the Tacoma computer just reads the pressure, and if it is too high or too low from the set pressure, an idiot light comes on. The TPMS sender's serial number has to be entered into the Tacoma's system, so it doesn't read the tire pressure of the other Tacoma passing you on the freeway.
The lith-ion battery is supposed to last 8-10 yrs in the sender unit. It is NON-replaceable.

 

I dummied the TPMS ECU.

I soldered in a couple of resistors to fool the ECU into believing all sensors are reporting correct pressures. Non of my wheels have TPMS valve stem assemblies. No lights show up on the dash except during start up.

 

This is a great layout of your options: http://www.tacomaworld.com/forum/wh...ts-i-e-winter-summer-street-off-road-etc.html

 

What does that have to do with his question?

 

Just a helpful tip.