I'm not 100% sure on this because the manual is kind of vague on it, so dont quote me on this but if someone wants to try it and let everyone know --

1. Make sure the tires are cold and you have not driven the car for a while
2. set the tire pressure in all the tires to the same pressure and to whatever value you want to use as the minimum tire pressure (the value that if the pressure drops below xxx psi, you want the warning lights to go off)
3. There should be a pressure initialization switch underneath the dash on the drivers side (you'll have to stick your head underneath there. It's pretty far back).
4. With the car parked and the engine running, press and hold the initialization button for around 3-4 seconds until you see the message "pressure initialized" and the flat-tire indicator flashes slowly 3 times. (not sure if the wording will be exactly the same, but something to that effect)
5. Leave the car running for at least 20 minutes (you can drive around if you want, but if you turn the car off earlier, you will have to start all over. Dont know if there will be a message telling you it is done)
6. add air to set the tire pressure to whatever "normal" value you want

I think this will set the baseline tire pressure that the TPMS system uses for determining when the tire is low. I dont have an IS but I have a 3GS and the information above was extracted from the owner's manual for the GS. I dont see why this sequence wouldn't work on the IS also.

 

I live in DFW Texas, I have an 07 350 with 18 spyders. I had the warning lights come on, so I drove around and checked the pressure all were in the mid 20's, I put air in all the tires setting them at 32 re-intialized them system. So a week later the light goes off and I just ignore it and drive a good 3 miles and get this feeling I should check.. Yeah I had a completely flat tire , so I guess all in all the system is somewhat helpful. But if it helps any I was at the dealer yesterday and he told me that the system will go off at 28 pounds of pressure..

 

From the factory service manual:

So anyone telling you anything else is not checking the factory documentation, they are just guessing and blowing smoke up your leg. NOTE: the front and rear pressures are ALL the same, no matter what tires you have.

Also from the Factory Service Manual - And Also from the New Car Features Manual - Although none of the documentation directly states this, all the tests indicate this value to be significant - >5.8 psi pressure drop will turn on the low pressure indication. Example I have also noted from practical experience that the 5.8 number seems to be right. So, in the unlikely event your car was delivered with the correct tire pressure and it dropped down to 32 psi (on an uncalibrated gas station gauge), it's no surprise to me that the light came on.

It's far more surprising that your dealership has not been properly trained on advising customers about problems with this system since it is Federally mandated for all MY 2008 cars, and it is present on all new or redesigned platforms. It even debuted on the 2007 Scion tC, and we know those cars are not even close to the same level of technological expectations as Lexus are.

If I were you I would call Lexus Corporate and tell them about the poor guidance you received from your dealer and suggest they receive the requisite training soon, or they will be inundated with calls from frustrated customers, who, like yourself, get very unhappy when the warning lights come on for any reason.

 

No, this is not the correct procedure for the IS. According to the 3GS Factory Service Manual, your description is basically correct. However, the FSM for the 3GS does not include any language about the pressure adjustments you describe. It just tells you to set the pressure to the specified pressure (230kPa, 2.3kgf/cm2, 33psi) and perform the initialization (including the 20 minute registration process). To test the system, it says let out 20 kPa (2.9 psi) in 15 seconds or less, not 40 kPa (5.8 psi) in 30 seconds as the IS manual says. Apparently there is some difference in the software.

 

i have the same problem and im in hawaii with the temp.. never droping below 80. the tire warning went off this morning on my way to work. i decide to deal with it til i finished. at the end of the day the tire light was still on. so i decide to put air ofcourse. i put 38psi for all four tires and still had the warning light on. wat should i did

 

I apologize in advance if I could have answered this question myself by simply looking under the dash, but where is the reset button?

 

Great information lobux. This is the key to your problem. Make sure you set your pressures to 35 psi in the front and 38 in the rear. Let us know if this fixes the issue!

 

It's one of the features of the satellite button. The same one you use to select the AFS on/off, MAIN/secondary tire set, etc. Just below and to the left of the steering column.

 

The sticker on my door jamb says 37 psi rear. Unless amended by a TSB, I usually consider the information on those stickers to be accurate for my particular car. mariabee has promised to come back and tell us what it says on her sticker, but I'll bet it is 35/37, and she has simply been underfilling her tires based on incorrect information from her dealer.

 

Ah, I understand, you just set the indicator the position that would select the main set of tire sensor, and then hold it for more than three seconds. Thanks for the info.

 

This made me think about it, and the chart in the FSM is wrong. 2.6 kgf/cm^2 is 37 (36.98) psi, not 38 psi. So the door sticker's 37 psi is correct (because I know the Japanese use kgf/cm^2 for everything.)

I've also seen this from time to time on torque specs. I always work from the Nm number. I never trust their conversions.

 

Yes, after you service the tires to the pressure indicated on the driver's side door jamb, with the engine switch in the ON position.

 

To make all of this pressure setting easier I'd recommend investing in a portable air compressor. I bought a Coleman at Home Depot for $100 on sale, and it includes a nice tire chuck and gauge. I just spent 45 minutes checking and adjusting all three of our cars. It is far easier doing it in your garage/driveway with the tires cold, rather than searching out a place that will cost you 50 cents. Often they don't work right or are out of order.

 

That was my suggestion way back in the third post in this thread. No need to spend that much. I bought one of these http://www.hechinger.com/web/catalog...A39C585AB7CF7B
for my dad about 10 years ago, and it's still working great.

 

hey evitzee...that picture in your sig is sweet! do you have a wallpaper size???