MarshalWeb

I just upgraded my wheels and tires on my 04 Lexus LS 430 and the guys at Goodyear told me that the stock rims (and tires) did not have the low pressure tire monitors in them. They showed me the stock stems and from what I could see he, seemed to be right.

Now, I bought this car just a week ago used, so it is entirely possible that the tires that I just replaced may not have been the originals (but they look like they probably were).

The strange thing is... last week when I was driving this car home with those old tires and rims, the 'Low Tire Pressure' warning light came on and I pulled over at a gas station and checked... and sure enough the front right tire was pretty low. So I aired up the tires and the warning light stayed on until I pressed and held that little reset button under the dash.

So... how could this have happened if I didn't have the tire sensors in my tires? Or am I missing something here.

-MarshalWeb

Nelson

I have been told that in the 2004 LS the low pressure indication is not actually a direct reading of tire air pressure. It supposedly works by sensing a change in the frequency of the sound coming from each tire/wheel.

Apparently other Lexus models and years have direct air pressure sensors...but not the 04 LS.

I was told this by the dealership. The write-up person didn't know and had to check with a specialist to get the answer.

Can someone confirm this.

bb430

iTrader: (1)

I have an 01' UL so I don't have this w/my car, but my guess would be that the system use ABS sensors to read off the rotation differents on each axle to warn you of low pressure...

Dr. Jekyll

iTrader: (1)

You are all correct. The TPMS is a passive system not a direct one. The computer senses which tires is out of sync with the others and sets the system off. It is very important to reset the system everytime an adjustment is made. The rest switch is under hte dash under the ignition key.