TPMS?? Hell, I don't know...

[moredes15]

2007 Prius. At 512 miles, I replaced the sorry 15" OEM rims and tires with a set of 17" Tc Scions. (When the car was delivered, the TPMS light was on steadily. I reset the TPMS at that point--when the car had 8 miles on it--and from then on, the light only came on during the start-up check.) Things worked just as I think they're supposed to, until I installed the Scion rims. The seller says there are no TPMS sensors in the 17's. I drove for ~80 miles before the TPMS indicator came on and stayed on.

I think I did something 'wrong'. I followed the directions and reset the TPMS sensor (under the steering wheel) by holding it down as the manual instructs--until the TPMS indicator light starts to blink very slowly 3 times-- I released it, and tested the system by starting it up. TPMS came on almost immediately (within 2 miles). I stopped and turned the car off and reset the TPMS again. I went through this entire procedure twice--reset, drive, stop, off, reset. At the end of the second trial, I didn't have to drive anywhere; the TPMS sensor stayed on after the start-up check.

So I turned off the car, and reset the TPMS consecutively 3 or 4 times (I wasn't counting). That was 11 days ago. The TPMS sensor now comes on during the initial start-up, but it goes out (last, but quickly) every time now. I have almost 400 miles on the car since the last TPMS reset; it's done freeway miles in 40-mile increments @ 75mph at least 6 times since then, and the rest is city driving. (The OEM wheels and tires are stored in a shed ~200 feet away from where the car is parked at night.)

I'm not complaining, and I hope I'm not jinxing myself. Any ideas??

[Cheap!]

<div class='quotetop'>QUOTE(moredes15 @ Nov 29 2006, 11:17 PM) [snapback]355582[/snapback]</div>

I'm not complaining, and I hope I'm not jinxing myself. Any ideas??
[/b]

Yes.
Go inside your original rims and remove the four battery powered tire pressure sensor transmitters and place them in your new rims. Your car has been looking for them and misses them immensely.

[eagle33199]

To elaborate, the system will light up if it can't detect the sensors. Now, this doesn't happen immediately, and there are certain conditions which seem to favor it staying off. if you store the old tires near the car every night, it appears that you'll rarely see the light, as it can get regular updates from the sensors. however if you're then on the road for several hours it will finally realize that the sensors aren't there and the light will come on.

As for why the light is staying off now and it wasn't before... you're guess is as good as mine - the maximum distance for sensor range is supposed to be around 60 ft.

[Allannde]

<div class='quotetop'>QUOTE(Cheap! @ Nov 29 2006, 10:19 PM) [snapback]355594[/snapback]</div>

Yes.
Go inside your original rims and remove the four battery powered tire pressure sensor transmitters and place them in your new rims. Your car has been looking for them and misses them immensely.
[/b]

If the rims of your new wheels are the same or very nearly the same shape as the original wheels the sensors will fit. If not, they may not fit.

It is not necessary to remove the tire to remove and replace the sensors. However you must let all of the air out, break the bead and depress the bead 3 or 4 inches at the point where the valve stem emerges from the wheel. The sensor is held in place by a nut on the outside and with the nut removed will slide into the the the inside of the tire so be careful not to drop it.

Your tire/wheel guy should be familiar with these things if you have one.

[Sarge]

<div class='quotetop'>QUOTE(Allannde @ Nov 30 2006, 11:08 AM) [snapback]355683[/snapback]</div>

It is not necessary to remove the tire to remove and replace the sensors. However you must let all of the air out, break the bead and depress the bead 3 or 4 inches at the point where the valve stem emerges from the wheel. The sensor is held in place by a nut on the outside and with the nut removed will slide into the the the inside of the tire so be careful not to drop it.
[/b]

Now, I'm no tire installer, but if the tire bead is broken as you explain then the tire simply refilled, will the seal be as good as before, or is more "sealant" (whatever it is) needing to be applied?

Sounds like an awful lot of work; because it would then be necessary to do the same with the second set of rims to reinstall the sensors. Would have been nice if Toyota had come up with an "external" sensor on the outer part of the valve stem or something that could be transferred more easily by the owner from one rim to another, but then I guess those would be easier to steal. <_<

[galaxee]

some other recent threads discussing this strange phenomenon:

http://priuschat.com/index.php?showtopic=26918
http://priuschat.com/index.php?showtopic=26919
http://priuschat.com/index.php?showtopic=26131
http://priuschat.com/index.php?showtopic=25797

[JayGoldstein]

I also am seeing, shall we say, "inconsistent" behaviour with the TPMS warning light after installing wheels/tires without sending units (see my experience in http://priuschat.com/index.php?showtopic=26919).

I also tried resetting the TPMS, but it had no effect: the warning light kept blinking and then staying on. However, the light has stayed off (it doesn't even blink momentarily upon starting) for two consecutive days.

Based on what others have said, I suspect that the light will come on again the next time I take a long drive.

[Allannde]

<div class='quotetop'>QUOTE(Sarge @ Nov 30 2006, 08:39 AM) [snapback]355700[/snapback]</div>

Now, I'm no tire installer, but if the tire bead is broken as you explain then the tire simply refilled, will the seal be as good as before, or is more "sealant" (whatever it is) needing to be applied?
(snip)
[/b]

No, it is not complicated. Tubless tires do not require a "sealant" as you say, although a lubricant is usually used to make it easier for the tire to slip onto the rim. At a tire shop, this transfer could be done in just a few minutes with the time to mount and dismount the wheels taking the most time. The one that sold you the new wheels might even do it without charge if you ask nicely.

The threads galaxee referred you to are worth reading.

[JayGoldstein]

<div class='quotetop'>QUOTE(JayGoldstein @ Nov 30 2006, 11:12 AM) [snapback]355726[/snapback]</div>

Based on what others have said, I suspect that the light will come on again the next time I take a long drive.
[/b]

Just to update, sure enough, the warning light did come on during the next extended drive. Once again, for the next couple of days after the light first came on, it would flash and then stay lit each time the car was started. This morning, when I started the car, the light came on. I drove about 5 km (3 mi) and parked the car. When I started the car, there was no warning light.

The TPMS certainly works in mysterious ways when no sending units are present.

[onerpm]

<div class='quotetop'>QUOTE(JayGoldstein @ Dec 7 2006, 12:56 PM) [snapback]358908[/snapback]</div>

The TPMS certainly works in mysterious ways when no sending units are present.
[/b]

and even when they are present. for the last week or so, my light has been coming on each morning, even though my OEM wheels are sitting right in front of my Prius in my garage. For the first month or so after I mounted the snows, the light never once came on. The first time it came on was after about an hour on the highway on a trip out of time. Now it comes on all the time!

rpm