TPMS experimentation with '06 and scantool

<div class='quotetop'>QUOTE(galaxee @ Nov 3 2006, 09:01 PM) [snapback]343616[/snapback]</div>

I don't see any lack of consistency with what happened. The pressure monitoring system was doing exactly what it was designed to do - monitor the pressure of the tires. The lack of signal shouldn't set it off; any number of things (radio interference would be my first thought) could lead to someone thinking that their tire pressure is low if the computer equated lack of signal with low pressure.

Now if there was a, "My God, your wheel has fallen off of your car" sensor, then yeah, that should have been going off...

 

I agree with rfred. I don't know exactly how the TPMS sensors work, but if I were designing the system I wouldn't bother having all the sensors constantly transmit "I'm OK." It would be easier to wait until the pressure was low and send a message "Hey, pay attention to me! My pressure is low!"

(sure wish I had access to a scantool )

 

<div class='quotetop'>QUOTE(galaxee @ Nov 4 2006, 07:14 AM) [snapback]343770[/snapback]</div>

If we are concerned that the sensors have failed, we can let air out of the tires and see if the warning light comes on. It sounds like a trade off between a warning light which stays on when it is not needed and the probably *unlikely* event of a sensor failure.

All of this tells me that a reading of the actual tire pressure on the MFD would be a lot more helpful especially since that information is available (on the Scantool).

Edit: Of course one would still need to determine which wheel the pressure represented since the sensors are not keyed to the wheel location.

 

<div class='quotetop'>QUOTE(galaxee @ Nov 4 2006, 06:50 PM) [snapback]343984[/snapback]</div>

The test that your DH did was very helpful to an understanding of the TPMS.

If I understand your post correctly, we miscommunicated. The tradeoff I was referring to was the one made by the Toyota engineers. I fully agree that some indication of a sensor failure is needed. I don't expect a change which will affect my car, but I do see that abiility to see the actual pressure may be an answer to the problem. In the meantime, I will treat the TPMS as a suppliment to and not a replacement for hand checking of tire pressure.

 

I can't speak to how far the tires can go from the car without turning on the light, but mine did come on last night thanks to the change in temp. I was down to 28 in one tire, 30 in the other three. I can't say how accurate this was since I had to buy a new gauge. Will compare with my dad's gauge if I stop there on my way out of the city Friday.

I'm hoping that this is the cause of most of my mileage drop. With all 4 back at 35, I'll let ya know after my next tank. I'm doing a 500 mile trip next weekend with 4 adults, so a tank shouldn't take too long.

 

<div class='quotetop'>QUOTE(HokieHybrid @ Nov 4 2006, 08:28 PM) [snapback]343990[/snapback]</div>

you know that there is a 2 psi differential front to rear on the Prius.

 

Question! I have heard that the tire pressure sensor operates from the rotation of the tire.Does anyone know at what speed it starts to work?

 

OK, now that I have installed my snow tires on a set of steel rims, I can chime in with my strange experience here.

Three days ago (Friday), I had a set of X-Ice snow tires installed on a set of brand new Toyota OEM steel rims at Costco. I explicitly told the guys NOT to transfer the TPMS sensors from the alloy rims.

When the job was done, I drive away - no TPMS light! Hooray!

I ran a half-dozen short errand trips over the weekend, and this morning (driven about 85km since the tires were installed) the TPMS light did the flash-for-60-seconds-then-stay-on routine.

Interestingly, I put the car in Park to drop off my wife this morning and as soon as I put it back in Drive (having not shut off the car), it triggered the light. It flashed then remained on for the last 15km of my drive. <_<

When I arrived at work, I shut the car off and started it again, and the light came on again after flashing, indicating a problem with the system (such as absence of sensors...? )

Not sure why it would have taken three days and about 100km of driving to kick in...? :huh:

 

<div class='quotetop'>QUOTE(Sarge @ Nov 20 2006, 09:54 AM) [snapback]352143[/snapback]</div>

It could have been that another 06+ Prius came within the ~60 foot range while you were dropping off the wife.

Wouldn't it have been cool if you could of, at the time, rolled down your window and say to the other Prius driver, “He buddy, that light on your dash means you have low pressure in your tires.â€

 

<div class='quotetop'>QUOTE(galaxee @ Nov 20 2006, 11:30 AM) [snapback]352198[/snapback]</div>

Dooh! What do I know . . . I only have a lowly '05 . . . and lately, I have been spending most of my time in Fred's. -_-

If I were a conspiracy theorist who knew what he was talking about, I would have suggested that Sarge chase down that other car and ask them what they are doing with his tires. :lol:

 

<div class='quotetop'>QUOTE(galaxee @ Nov 20 2006, 01:55 PM) [snapback]352176[/snapback]</div>

I did take original rims home with me, and in fact store them about 3 feet in front of the car.

However, I did leave the house numerous times over the weekend (leaving the rims at home!), and yes I drove more than 60 feet away... :lol:

So very bizarre... :mellow:

<div class='quotetop'>QUOTE(Sufferin' Prius Envy @ Nov 20 2006, 03:07 PM) [snapback]352230[/snapback]</div>

Heh heh.. :lol:

I still think it would have been way cooler if there was a page in the "Info" screens to show current tire pressures rather than just a lame light when one loses 25% pressure. I realize the computer does not "know" which sensor is at which corner, but with the technology in this car couldn't Toyota have just put the TPMS receiver at one corner of the car and determined the sensor location by relative signal strength or something?

The car is so smart in so many other ways... being able to display your tire pressures onscreen would have been one more really impressive geek toy to show passengers.

 

I have 2 sets of wheels with sensors. The set I am currently running are my Enkei wheels with the sensors registered with the car. My other set are a stock set up with sensors not registered. I put the stock set a while back just to play, and the warning light didn't come on for a couple of days. Then once it did it never went away. I then put my "bling wheels" back on, and the light went out. I was really surprised that it didn't recognize a problem with other sensors sooner.

 

Maybe the OEM TPMS in the '06+ prius isn't on par with the several
aftermarket systems that are out now. With those, several things
are true:
__ * the sensors shut down after a certain period of no movement
__ * the receiver is trained to know which wheel is which
So if any of the applicable statements about the Toyota system are
true, then it is truly a lame, under-functional knockoff.
.
The 60-foot range is interesting, though. Is DH still using a
Mastertech, or did they dump the new system [what is it, SPX?
Snap-on?] in his lap? Not that the scantool should matter in this
case ... it would not surprise me if the TPMS controller continues
reporting the last-seen value for a while. There are several
engine parameters, for example, that continue being reported by the
ECM which would be "impossible" after the engine has shut down.
Such as injector time. That's the car's fault, not the scantool.
.
How long will it take for someone to build the universal "all your
tires are flat" transmitter, a la "tv-b-gone"...
.
_H*