There are no sensors in the wheels to measure tire pressure. The system measures the rotational speed of the wheels and compares them. It can sense rotation because it has to in order to control and activate the anti-skid brake system.

 

Just checking for a way to reset my tire light. Off topic it is nice there is no TPMS on the LS it would just be something to go wrong. I have a Highlander now it is an 010 and the sensor was 70 and the programming was 100 but under warrantee.

 

Hi, warm...
What year LS430 are you asking about? If 2005, this is the text from the Owner's Manual:
This message indicates the tire pressure warning system
is initialized. After replacing the tires or wheels, adjust all
4 tires to specified tire inflation pressure and initialize the
tire pressure warning system. To initialize the system,
turn the ignition switch to “ON” and push the tire pressure
warning system reset switch for longer than 3 seconds
with the vehicle stopped. The above message appears.

As mentioned earlier in this thread, the 430 TPMS measures the pressure indirectly, by comparing the current tire circumference to the reference circumference recorded at the "system reset".

 

Hey Geno! I reset the button on my 2004 LS, did not see a "Initialize" but prolly missed it. What dial is to the right of the button, what is it for. Thought I knew most everything about this car oh well that is what you folks are for. Happy Holidays

 

The description is pretty well hidden, but p.30 of the 2005 owner's manual says:
You can adjust the volume of the beeps which confirm the
locking or unlocking the doors or remind you when the
doors are not completely closed.
Turn the volume adjustment **** counterclockwise to
increase the volume or clockwise to decrease it. The beep
sound is completely deactivated when you turn the ****
clockwise until you hear a click.

 

There are absolutely no wireless tire sensors mounted in the tires on any LS430 ever made. I personally have run into several Lexus service writers that don't understand this - amazing but true.

As previously posted on many occasions, the relatively primitive (but ahead of its time at the time : ) design of the TPMS system in the LS430s works only by sensing different rates of rotation of individual wheels as a by product of the ABS system. There are no in tire sensors.

To reset the TPMS system when it has thrown an alarm code, first check and put air in the tires to bring all 4 tires up to recommended air pressure (per pressure listed on driver side door plate) and then, and only then, reinitialize the TPMS system per the instructions in the manual.

And check your spare tire pressure manually at least twice a year. There are absolutely no sensors of any kind on the LS that monitor the spare tire. You could have a completely flat spare or you could can take the spare out of the LS430 trunk and the ABS based TPMS would have no idea there is any issue with the spare and you would be happy as a clam until you got a flat and tried to use the spare.


Note the LS460 has TPMS that uses the more modern in wheel sensors - so it monitors all 5 tires for pressure using wireless in wheel pressure sensors. This a much more precise and useful system and works great until the batteries in each wireless pressure sensor die - then you get to pay to dismount all the tires and replace the sensors (list price $112.50 each) and remount and re balance for $$$$ since TPMS sensor batteries are not replaceable.

 

Jabberwock has it right.
The only question I have is that some people have said that the rotation rate comparison is between wheels (using currently measured rates), and I believe that is incorrect.
I think that each wheel is individually compared to its own reference value established when the system is "initialized" following the procedure documented above.