IRBA

I bought an additional set of winter tires WITHOUT TPMS and swapped them on today.

The weird thing is that the warning light didn't come up, and I'm wondering if the TPMS system on my car is functioning AT ALL...

anyone with any ideas?

Bennyboy

maybe its just a matter of time. Just sit on it for a while and see what happens. This would be interesting though, if it didn't work i'd actually be a little happier. TPMS is something i don't need.

zoltiz

It will come up. Give it couple of days.

IRBA

Wait for a few days? If this is how the system is SUPPOSED to work, then I'll be very worried....
This means that if I had a flat tire, the light probably won't come up until my alloys are cutting the road so hard that sparks are flying all over the place like fireworks...

Andyman

IRBA,
I don't think that's how they work. I'm certainly not an expert on TPMSs or anything, but allow me to share my experiences and the resulting guess at how these things work. I switched to snows also, but had the snows mounted on my factory rims. Then I ended up putting two of these new snows on our other car (03 Vibe), and two of the older Vibe snows on the back of the xD. But that's not important - in the end, only the front two tires on my xD have the TPMSs. And the weird thing is they seem to be working! No lights on for several days after switching the tires. Then one morning it was really cold, and the tire pressure light came on - I suspected that was just the time lag, and it would be on for the duration, since the rear tires don't have sensors. But then once it warmed up a little, the tire light went off. I've heard this elsewhere - that you can get a warning light when the pressure drops due to temperature, which then goes away when it warms up. That was about 2 weeks ago, and the light hasn't been on since.
All that to say, I suspect the sensors work by sending out a signal only when there's a drop in pressure. So if all is well, and at least some of the sensors are present, you don't get a warning light. But once one tire's pressure drops, the light goes on. So I'd guess that you'd get a warning light long before you're destroying your rims.
Can anyone verify any of these ramblings?
Andy
(BTW - it's pretty cool to have 2 vehicles with the same bolt pattern and tire diameter - here come the 8-wheel rotations!)

Bennyboy

Do you need a light to tell you, that you have a flat tire? i think the light is there to monitor tire pressure just so that you don't have 20 psi in one tire and 40 in the next. I think its supposed to help with Gas and other reasons other than driving on a flat tire. If you had a flat, trust me you really don't need a light to tell you that.

ChelsDS

Hrm I don't know the psi difference, but I think when its between 5-10psi difference in a wheel compared to the others, the light goes on. I had my light bugging me most of the weekend and finally got around to checking the tires. Shooo'nuff I needed to inflate a tire.. immediately lol.

Though as to the OP's question, no idea why its not turning on. Go back to the dealer and see what they say is the only thing I can think of.

zoltiz

Kinda what Andy said. The system reacts pretty much immediately when the sensor transmits that the pressure is lower than spec, but if there is no transmission, then there is no light. I drove on old tC wheels for couple of days and the light did not come on, but I've seen posts about the light eventually coming on. It does not mean that it will take the TPMS a week to notify you of the lowe pressure.

But I see how one could easily jump to a conclusion that TPMS blows because it does not light up when you remove a part of the system.

IRBA

I was just joking~ I'm even able to feel the PSI dropp from 33 PSI to 28 PSI~ The feeling of the ride becomes quite soft when it reaches 28 PSI!

It seems like everybody else are experiencing this same kind of situation, which seems to be a very nice design for the TPMS system! I hope the light won't go on too soon... having a warning light on the dash is so annoying!

SLODEANIS

I put snow tires and new tpms sensors on my xD and placed my alloys in the garage with the programmed sensors. When I drove away, the TPMS light came on, but when I came home and parked in the garage, the TPMS light went off because the regular tires on the alloys with programmed sensors was nearby. The xD picked up the radio frequency right away and turned the light off.

I bought a second TPMS computer and mounted it near the original and had my snow tires programmed to that...You can see some pictures here:

http://www.flickr.com/photos/deanspictures/

zoltiz

Now that's creative!

a_german_named_hans

I don't have an xD. I've been rolling on steelies for a little over a month now. My TPS sensors are still in my rims and I have yet to get a TPS light *knock on wood*

IRBA

Cool, man~! Absolutely cool!
How did you get that additional TPMS computer, and can you show us how you did all this?

SLODEANIS

The only thing I have to do now when going back to summer tires is take the glove box out, unplug the wire connector from the snow tire ecu and back into the summer tire ecu and wa-la. A new ECU is $300, but I got mine for $25 and programmed for $90, but I'll never have to do it again unless a sensor fails. I think all Toyota TPMS ECU's are similar, in fact, the "used" one I have has a completely different part number than the stock, but still works like it should.

As far as how I did it, look at the link above with my car apart. There is a bracket behind the glove box I mounted the ECU too...The ECU will have a bracket on it of some sort. It's the perfect location as the wire harness just reaches it without strain. I then left it plugged in, took it to the dealer and didn't tell them what I did...I just told them I have new sensors in my snow tire/wheel assemblies. NOTE: Make sure you write down the 7 digit TPMS sensor code or they will have to break the wheel down to get it...I gave them the 4 new ID's for each sensor and they programmed it. No problems no questions. I then set my tire pressures to 33 PSI as recommended and "reset" the system with the reset button. I then let air out of one of the tires and the TPMS light came on. I filled it back to 33 PSI and it turned off. Works perfectly.

dick_larimore

I put 4 winter tires mounted on steel rims on my new xD last Saturday. None of the steel rims had the tire pressure monitoring device. I drove for 4 days before the light came on. After 1 day of driving with the light on, it went back off and for the last few days the light has remained off.

I wonder if the TPMS in an xD without wheel sensors can be triggered by the RF signal from other vehicle wheels?