Thread

Ok, I've got the 18" Super 7's on my car which naturally don't work with the tire pressure monitoring system since there's NO anything where the rim mates to the hub to tell the car anything. The dealer awhile ago also confirmed this.

Anyways, over the past few days the low tire pressure warning light has been coming on. I get out of the car KNOWING that the system does not work with the 18" and I check the tire pressure on all 4 tires with my pressure gauge and they're all right where they should be.

Now, it usually only happens on the freeway after crusing at highway speeds for about 30 minutes. It has never happened on my commute to work or a lot of around the town driving. Even driving it hard does not make it come on. It just pops on as I'm crusing along the freeway.

Anyone else seeing this?

I'm about 700 miles from my 10k service so I'm thinking I'll bring it up then. Either way the car is going to have it's 10k done before May 7th because I'm driving down to Palm Springs for a one week vacation and I want to make sure it's in tip top shape like it always is. I'm so looking forward to that drive but not if the stupid low tire pressure light keeps coming on for no reason.

j0k3rzwild

I just had my 10k checkup . . the low pressure light didn't come on until I had the tires rotated. I took it to the dealer twice, they fixed it twice.

The light still comes on after a few mins of driving.

Is the 3rd time a charm? . . I will let you know.

JasonH

Your dealer is wrong. The tire pressure monitoring system on the tC has no pressure sensors. It uses the ABS sensors and reads the number of revolutions for each tire. If one tire is making more revolutions than the rest, it means it has a smaller diameter which means its air pressure is lower.

If your tire pressures are ok, reset the system (with the car stopped and ignition ON, press the "RESET" button in the glovebox until the pressure warning light blinks three times and goes out.) If it comes back on, check the tires again, then take it to the dealer to have them check out the system. If tehy say the system doesn't work with the 18s, then argue with them and/or call Scion corporate.

Eiso

yea, this has happened to me too!
dealer scratched my right rear wheel!
replaced it, then that light starts bugging me!

Thread

Interesting to say the least on how it determines that. I'll have to check the owners manual to be sure. But, yes, I am resetting the system every time it happens.

Something just occoured to me though, if it measures it via revolutions how is it overcoming the laws of physics? When you're turning the weels on opposite sides of the car are turning at different rates. Or is the system smart enough to know the vehicle is turning and hence not trip the light. So there must be some sort of threshold I suppose.

As for there not being anything, on the rear wheels I can see a rubber plug in the rotor that for awhile I've assummed is where the system get's info from the wheel somehow and mine has a rubber stopper since I don't have the 17"s. But, perhaps it's a parking brake inspection hole since I believe the parking brake on the tC uses a drum type setup for it instead of messing with the rear calipers.

Oh well, something to check when I get home.

Also, I should have mentioned this but, this all started happening after I had to have a tire replaced because I got a nail in it and because of where it hit the tire had to be replaced. This was at about 9k miles and I'd find it difficult to believe that the neglible tread wear on the other three compared to the new tire is the culprit. I should see if I do have a nail in any of the other tires since nails like to travel in groups and perhaps I have a small enough of a leak to be tripping the system.

DJIce

There's something you guys might be missing. There's a short reset and a master reset on the tire pressure system.

The short reset works in cases where that damn light comes on for no particular reason, or if you get a flat or something.

The hard reset isn't much more complicated, but its designed to reset the entire system, usually in the event of replacing wheels or tires, or both (as in this case). What you have to do is turn the car off, begin holding the reset light, and then turn the car on. The car will go through its normal start up sequence, and the Tire Pressure Warning Light will turn off. Meanwhile, you're still holding the button. After about 15 seconds, the light will flash three or four times. Once its done flashing, you can let go of the reset button. You have now performed a master reset. It is recommended that you do not do this on a short drive, and that the engine and computers be left on and the car be driven for at least 10 minutes in order for the computer to properly reset.

If this doesn't work, talk to the dealer.

Thread

So after doing a master reset take the drive or before, I'm assuming after but I'd like to be sure. ___-U-ME and all that.

JasonH

I explained it in my post - "with the car stopped and ignition ON, press the "RESET" button in the glovebox until the pressure warning light blinks three times and goes out." You do that after checking all your tire pressures. It's not that complicated.

It sounds like the system was never reset properly (you might have just hit the button to make the light go out.) The other possibility is that your new tire is the wrong size, but that seems unlikely. If you reset it and it keeps happening, take it to a dealer.

Thread

Ok, I got it, I was just a little confused by ignition on meaning either car stopped, engine not running, and key in the ON position.

So now it's engine running, hold down the reset until it blinks 3 times, which I imagine will take awhile since I do recall holding it down for a significant amount of time when it came on while on the freeway.

But, allow me another question, does the warning light need to be on to do this. I'm going to ___-U-ME no since this sort of reset would be required when changing rims, tires, etc. But, I'd like to make sure.

Thread

Ok I'm being an idiot and not reading correctly, must be work getting in the way. Anyways, I re-read the post and I believe the sequence is this.

1) Unlock car
2) Get in car
3) Put key in ignition but don't turn it
4) open glove box
5) hold down the reset switch
6) Move key to the ON position
7) Warning lights will go through their normal stuff
8) Wait until tire warning light blinks 3 times
9) Start engine
10) Take a nice long drive
11) Serenety

So, do I have it right or do I still have my head up my butt. And I bow before those that pointed out my ignorance about how the system works. I found a good writeup on it at tirerack.com.

Link

DJIce

Step 6 should be start vehicle. Eliminate step 9. Good luck.

JasonH

I feel like I'm bashing my head against a wall. Car does not have to be running. It can be, but as long as the ignition is in the "ON" position, it will work. Car MUST be stopped. Then, after you turn the key, no need to do two things at once, just open the glovebox and hold the RESET button until the pressure light blinks 3 times.

If you still can't figure it out, read your owner's manual.

JasonH

exposed29

Thanks for this information! Ever since I changed to different wheels I've had the same problem as the person that started this thread. Sounds like this will take care of the problem.

Thread

No, I figured it out, and it worked, no more light. And car stopped means several things to different people. Car nt moving is one of them, engine not running is another, it's all a metter of how you've come to be and how others around you use it. For me, car stopped means engine stopped as well.

VoLktc

my light came on and i run 18" volks. come to find out a screw was in my front tire. probably save me from a blowout going down the highway or something. thank you scion

Huey

lol i didn't even know my car had a low tire pressure light