I came out to see I had a very low tire on my 03. Since I got no warning on my dash I assume I do not have it.. I did have it on my 04 so it must have started in 04. Correct?

 

Yes! You might have no TPMS sensor installed in that tire and the computer does't recognize it.

 

I'm almost positive that you have the low tire pressure system in your 2003 but it doesn't use individual sensors on each wheel. Instead, it calculates the tire diameter using the ABS sensors. This means that the system is unable to detect low pressure if the car is not moving...

 

You are 100% correct there is no sensors in the inside of the rim it is and based of the abs system in the car the reset button is underneath the dash closest to the gas pedal, tbis was a revolutionary thing back in 2001-2006.

The standered tpms sensors that other cars have go were the valve stem is on the inside of the rim and have a life of 2-5 years due to to battery inside them. They are sometimes very finicky so if you have summer and winter rims make sure you have them mark what tire went were when they swap them over otherwise they will have to reprogram the sensors.

 

There are no TPMS sensors in the wheels on any model or year LS430. Every year of the LS430 uses an ABS based system (indirectly measuring wheel rotation while in motion) that does not have sensors mounted inside the wheel/tire.

 

On a related note, my TPMS warning goes on everyday after about 10-15 miles of driving. All tires are at pressure and nothing seems amiss. I clear the warning by hitting the button under the dash, only to do it 5 times again on the average day. I found some instructions on how to "reset the system" and I did get new tires recently: put the ignition in the "ON" position and hold the rest button until the indicator displays. I've tried this, but I don't see anything on the display after about a minute or so of pressing the button. Any ideas? The exact instructions are below:

Lexus LS 430 TPMS Reset Procedure

Relearn Code: LEX-2

Relearn Procedures:

1. Inflate all tires to pressure indicated on tire placard.
2. Turn ignition to ON position (engine off).
3. Hold down tire pressure warning reset switch until Pressure Initial indicator is displayed.
4. Vehicle will have to be driven at speeds above 19mph to complete

 

Here are a couple of TSIB's (Technical Service Information Bulletin) related to initializing the LS430 tire pressure warning system...