TPMS Tools

[White Shadow]

Originally Posted by wparsons

If all four tires are low, it can't detect a difference and will never let you know. The whole basis of it is using a difference in wheel speeds (averaged out so it doesn't go off in a corner) to determine if a tire is low. If all four are low there's no difference between wheels.

You're missing the point. The newer (generation 2) indirect TPMS systems don't need to detect a difference because they don't compare wheels speeds to each other. I thought I made that clear, but you may have missed it.

If you want to learn more about how it works, just do some research on second generation indirect TPMS.

[wparsons]

Without a reference point, it's essentially impossible to know if a wheel is low based on wheel speed. I did read a bit about how it can try to use vibrations, but how that's also extremely sensitive and requires more attention and resetting based on conditions.

[White Shadow]

Actually, I'll explain it in more detail for you, so you don't even have to do your own research. Here's the Cliffs Notes version of how it works:

Basically the second generation systems allow all four tires not only to be measured independently, but also to be compared to expected values based upon a variety of factors. The advantage here is a MUCH faster response time, so the driver is alerted of the low air pressure condition very quickly. For example, using the old system, wheel speeds change whenever the vehicle isn't traveling straight ahead. With the new system, that doesn't matter because none of the wheels is using any of the other wheels as a reference. Basically, the ABS wheel speed sensors monitor the speed of each wheel independently and when the speed falls out of range (due to a difference is the rolling diameter of the tire), it signals the driver and tells him which tire is losing pressure.

It works very well, as I learned on my car when I punctured the sidewall on a piece of metal in the road. I actually heard something when I punctured the tire, but I didn't know what it was. I drove less than a quarter mile when a message popped up on my screen telling me that my right rear tire pressure was low. I pulled over to the side of the road and saw a piece of metal sticking out of my sidewall. At that point, the tire still had some air in it, but it was completely flat within about 3 minutes.

As for downsides to second gen indirect TPMS, the only thing I can think of is that it obviously can't provide actual pressure info for the driver of the vehicle, since there are no sensors inside the wheels. But that's not a big deal anyway. In fact, I'd rather not have TPMS anyway, but I guess we're all stuck with it now. If people were more diligent with checking the air pressure in their tires, we would have never been mandated with TPMS in our cars.

Oh, one more thing about indirect TPMS-- the driver has to calibrate the system when a tire is replaced or if the tire pressures are changed. In my car, you simply press a button and the system calibrates itself. I guess that can be considered a disadvantage because the system isn't 100% passive.

[White Shadow]

Originally Posted by wparsons

Without a reference point, it's essentially impossible to know if a wheel is low based on wheel speed. I did read a bit about how it can try to use vibrations, but how that's also extremely sensitive and requires more attention and resetting based on conditions.

Vibrations? Never heard anything about that.

Read my prior post, but basically the unit is calibrated for the reference point. The system doesn't need a comparison between wheel speeds for anything anymore. That was only true for the old systems, which were more primitive and needed a much longer response time.

[wparsons]

Originally Posted by White Shadow

Basically, the ABS wheel speed sensors monitor the speed of each wheel independently and when the speed falls out of range (due to a difference is the rolling diameter of the tire), it signals the driver and tells him which tire is losing pressure.

How does it manage that without a reference? Unless it's using GPS as a reference it HAS to compare to another wheel (or all other wheels) to know if it's out of range.

[White Shadow]

Here you go...this is the system used on my car:

http://www.niradynamics.se/products/...sure_indicator

[White Shadow]

Originally Posted by wparsons

How does it manage that without a reference? Unless it's using GPS as a reference it HAS to compare to another wheel (or all other wheels) to know if it's out of range.

The reference is the calibration. The system knows how many RPMs the tire should be turning when it is properly inflated. No need to even look at a comparison with the other tires.

Edit: I believe the second generation system still looks at the other tires, but the point is that it doesn't need that data to determine if any or all tires have low air pressure. I wish I could find the tech article I read back when I got my car, but I can't find it right now. It really went into depth on exactly how the system works. In the meantime, here's a quote from NIRA's press material:

"Essentially, the NIRA Dynamics TPI system "learns" the radii and frequency characteristics of properly inflated tires. Then, it is able to detect whether there are deviations from normal, which would be a result of the loss of tire pressure (e.g., when a tire loses pressure, there is a change in the radius as the tire rotates, which has a consequent effect on the measured parameters). The system can detect a change in any or all of the tires (remember that the previous indirect systems measured pairs of tires unlike this one, which has inputs from each of the tires)."

[wparsons]

^^ You're missing the point....

Wheel RPM is fixed based on engine RPM and gear you're in (assuming you're going straight, with four equal diameter tires). Doesn't matter if you're running no tires, or over inflated tires. What changes is the speed you're going depending on tire diameter.

For a system like this to detect a wheel is over or under inflated it needs to know that the wheel is turning faster or slower than it should be at a given speed. Vehicle speed is indicated by output shaft RPM (or wheel RPM), not actual speed (which is why changing tire diameter effects the speedometer/odometer).

No sort of calibration in the world is going to be able to tell you if a wheel is low if all it looks at is the RPM that that single wheel is turning. You need some sort of reference to compare it to for it to have any sort of measurement. Be it a GPS speed reading, or comparing it to the other wheels, it HAS to compare to something else to determine if that wheel is experiencing an issue.

If all four tires are equally low the speed/rpm reading at 100km/h will still be the same as if the tires are at the proper pressure, but since the rolling diameter is smaller the car will be going slower. Unless you compare that to an external point of reference the car and sensors won't know any different.

[White Shadow]

Originally Posted by wparsons

^^ You're missing the point....

Wheel RPM is fixed based on engine RPM and gear you're in (assuming you're going straight, with four equal diameter tires). Doesn't matter if you're running no tires, or over inflated tires. What changes is the speed you're going depending on tire diameter.

Exactly. So why is it so hard for you to grasp the concept then? The ECM already knows how fast the wheels should be turning in any given situation with properly inflated tires.

For a system like this to detect a wheel is over or under inflated it needs to know that the wheel is turning faster or slower than it should be at a given speed. Vehicle speed is indicated by output shaft RPM (or wheel RPM), not actual speed (which is why changing tire diameter effects the speedometer/odometer).

Exactly. So far, you haven't said anything that I haven't already said, so I don't disagree at all. What you're not understanding is that a comparison between wheels is 100% unnecessary in order to detect a low air pressure condition.

No sort of calibration in the world is going to be able to tell you if a wheel is low if all it looks at is the RPM that that single wheel is turning. You need some sort of reference to compare it to for it to have any sort of measurement. Be it a GPS speed reading, or comparing it to the other wheels, it HAS to compare to something else to determine if that wheel is experiencing an issue.

Negative. If the wheel speed is a calibrated point, that's all the system needs to detect a low air pressure condition. You don't need GPS and you don't need to look at wheel speed data from the other wheels. That's complete nonsense.

If all four tires are equally low the speed/rpm reading at 100km/h will still be the same as if the tires are at the proper pressure, but since the rolling diameter is smaller the car will be going slower. Unless you compare that to an external point of reference the car and sensors won't know any different.

You just don't get it. Okay, I give up....I'm done here. I already gave you all the information you need to do your own research. Don't argue with me, argue with the company who designed the system. And if that's not enough for you, go argue with VW/Audi because they've been using this system for at least four years now.

Anyway, nice chatting with you, but I really am done arguing about this. You can have the last word if you want.:happy0180:

[wparsons]

If all the ECM knows is how many RPM a wheel should be turning at a given speed it has no way of knowing if the tire is low unless it compares to other wheels.

The only way the ECM knows how fast a car is going is by the output speed of the transmission. Since the final drive doesn't change while driving transmission output speed to wheel RPM is a fixed relationship.

Want to prove me wrong? Go put 35psi in all four tires, then calibrate it. Then drop the pressure to 25psi in all four tires and drive around to see if the light comes on.

The system can detect differences in all four tires (not just pairs of tires), BUT there has to be pressure differences between the tires for it to detect anything. If all four tires have the same pressure as each other there's no external frame of reference to tell the ECM something is wrong.

If the ECM knows speed by wheel RPM, and wheel RPM by speed and those are fixed together then how can it ever possibly know something is wrong without expanding its data to either GPS or the other wheels?

Fake numbers, but the theory is like this.

1000 wheel RPM = 100km/h indicated.

Over inflate all four tires, at 1000 wheel RPM the speedo will still show 100km/h, but you'll be travelling faster if you measure with radar or GPS.

Under inflate all four tires, at 1000 wheel RPM the speed will still show 100km/h, but you'll be travelling slower if you measure with radar or GPS.

[neutron256]

Wow people really need something better to argue about one here.

"Second generation iTPMS can also detect simultaneous under-inflation in up to all four tires using spectrum analysis of individual wheels."

http://en.wikipedia.org/wiki/Tire-pr...itoring_system

I don't personally understand it, and it doesn't work as well as direct sensors but it can be done.

[ngabdala]

I had the same issue. My dealership told me that they are using Toyota's code and that I would need to ask Tirerack for the code. Tirerack was no help

Originally Posted by developer

I just wanted to give people a heads up on which TPMS tools work and don't work for our cars (FRS, BRZ).

ATEQ VT30 (Basic Sensor activator) --> Not currently supported (1st Qtr 2013)
ATEQ VT55 (Mid level sensor activator) --> EDIT: Neutron256 reports that VT55 will work with the Toyota protocol

ATEQ QuickSet (TPMS reset tool) --> Supports our cars with latest software

I got the above support dates directly from ATEQ.

Tirerack messed up and forgot to record my TPMS sensor IDs and I had to go to several tire shops to find someone that had a sensor activator that would work on our cars. A local shop that had a Bartech device tripped the sensor using the Toyota protocol. My Subaru dealer didn't even have the tool, they wanted to pull the tires off to get the IDs.

Once I finally got the IDs the ATEQ QuickSet tool made reprogramming the ECU TPMS IDs quick work. It should take less than 5 minutes now to go from my Winter to Summer tires. You program the QuickSet tool with the TPMS IDs for both your Winter and Summer tires using a Windows computer. You disconnect it from the computer and plug it into the OBDII port. Push either the Summer or Winter button. If the light goes from a flashing green to a solid green your done. The Windows software supports up to 4 cars at a time.

[BaBaFlyingSheep]

Can anyone verify if BlueDriver or OBDLink MX+ works with resetting the TPMS?

Or does anyone else have any other recommendations other than ATEQ?

And does anyone know if the 2nd gen is the same as the 1st gen? Requiring one of these tools?

[saltywetman]

Borrow ATEQ quickset from someone if you can and pull your OEM TPMS IDs... Buys some Schraeder programmable TPMS for your new wheels and clone them to factory codes. No more flashing ecu needed.