Will Model D finally deliver REAL TPMS?

[scottm]

..yay, another TPMS thread.

TPMS are new-to-me, and somehow I've managed for the last 30 years w/o them.

I think Tesla has struck a good balance of information on TPMing: only show if there's a problem. Tire pressure will change with temperature, and altitude. Showing raw pressure data fluctuating would freak some A-type people out who would undoubtedly begin modifying their driving style to compensate in order to keep the tire pressure in the "sweet zone" of pressure for maximum range.

...or, it would get old fast.

Get off your duff and figure out which corner is complaining.. and while you're at it, check the condition of your tires. I've heard people here being "surprised one day" to find they've driven rear wheels down to the metal cords. Now, that's out of touch!! Blame it on some missing sensor that didn't detect tread depth for you? Metal shard detector? Rubber bulge detector? Put down the devices and check the physical world sometimes.

Next, people will want to know battery pack temperature or something on the display all the time...

I'm sorry I even mentioned that just now. Expecting thread on that soon.

 

[tga]

I recall, however, that our system uses a singular receiver instead of one in each wheel well. That is, we know the pressures of each individual tire, but not the actual current location of that tire. That would go a long way towards explaining why Tesla hasn't exposed this, as it would be confusing to owners.

There are (broadly) two ways to design a direct TPMS system:

1 - Sensors with low(-er) powered transmitters and a receiver near each wheel. The receiver can lock onto the strongest signal, and the car therefore "knows" which pressure reading comes from each wheel.
Advantages - no need for learning tire locations, sensors don't need unique ID's (but that isn't really much of an advantage), lower TX power may mean longer battery life.
Disadvantages - more expensive (4 receivers vs 1)

2 - Sensors with high(-er) powered transmitters and a single receiver
Advantages - Cheaper expensive (4 receivers vs 1)
Disadvantages - need to learning tire locations when rotating/changing wheels, sensors need unique ID's to match which tire to which corner, higher TX power may mean shorter battery life.

One receiver does not mean the system can't know the location of the tires. I don't claim to understand every manufacturer's TPMS system, but every direct system I know of actually uses 1 receiver, since the advantages of 4 don't really outweigh the cost savings.

GM definitely uses a single receiver system with unique ID's (serial numbers) in each sensor. As long as you re-learn the locations of each sensor when rotating tires or changing to winter tires, it works fine. On the GM system, re-learn means put the system in learn mode and then trigger each sensor in order, starting at driver's front and working clockwise around the car (pass front, pass rear, driver rear). Triggering the sensor means raising/lowering pressure, using a "relearn tool", or possibly a big magnet.

Any time you have to "re-learn" the sensors when rotating or changing wheels, you can be pretty sure that (a) you have a single receiver system, and (b) when properly set up, the system knows which sensor goes with which corner.

 

[Gizmotoy]

One receiver does not mean the system can't know the location of the tires. I don't claim to understand every manufacturer's TPMS system, but every direct system I know of actually uses 1 receiver, since the advantages of 4 don't really outweigh the cost savings.

...

Any time you have to "re-learn" the sensors when rotating or changing wheels, you can be pretty sure that (a) you have a single receiver system, and (b) when properly set up, the system knows which sensor goes with which corner.

Right. In systems with one receiver, there's no way for the car to discern which wheel is on which corner and the configuration has to be manually modified by anyone who touches the wheels any time they change positions.

Once the wheels move the system has to be reprogrammed with the new locations. It's a manual process and thus prone to error, so it can be confusing for owners. On the systems with one receiver that report location to the owner the reprogramming often gets forgotten during rotations, leaving the owner to think there's an issue in one corner when the problem is actually somewhere else. I'm told, anecdotally by a mechanic friend at a tire shop, that this happens with extreme regularity. I do wonder if it's true broadly, but I wouldn't be surprised. It's likely Tesla decided it's better to provide us with no location information at this time rather than potentially bad location information.

That's why many (most?) of the systems that report location use individual receivers, as in MB and Porsches.

 

[tga]

Right. In systems with one receiver, there's no way for the car to discern which wheel is on which corner and the configuration has to be manually modified by anyone who touches the wheels any time they change positions.

Once the wheels move the system has to be reprogrammed with the new locations. It's a manual process and thus prone to error, so it can be confusing for owners. On the systems with one receiver that report location to the owner the reprogramming often gets forgotten during rotations, leaving the owner to think there's an issue in one corner when the problem is actually somewhere else. I'm told, anecdotally by a mechanic friend at a tire shop, that this happens with extreme regularity. I do wonder if it's true broadly, but I wouldn't be surprised. It's likely Tesla decided it's better to provide us with no location information at this time rather than potentially bad location information.

I get your point - I misunderstood your original post to mean "single receiver systems can't report pressure at each corner at all". I had to re-learn the sensors on my truck after the local tire shop forgot to once when rotating. I've fixed it for friends and family members w/ the same problem.

One would hope that Tesla could hire slightly more competent, less sloppy mechanics.:wink:

That's why many (most?) of the systems that report location use individual receivers, as in MB and Porsches.

My 2004 911 predates all this TPMS silliness, so I don't know what Porsche does these days. As I mentioned, GM uses a single receiver, and (if relearning is done properly at rotation), they report individual pressures at each corner. If I were being pedantic, I'd take issue with "many/most" and say there are a lot more GM cars out there then MB's and Porsches.:smile:

 

[Gizmotoy]

I get your point - I misunderstood your original post to mean "single receiver systems can't report pressure at each corner at all". I had to re-learn the sensors on my truck after the local tire shop forgot to once when rotating. I've fixed it for friends and family members w/ the same problem.

One would hope that Tesla could hire slightly more competent, less sloppy mechanics.:wink:

Assuming every Tesla has its wheels touched exclusively by Tesla Service Centers, that would make sense. The chances of that happening are zero, though.

My 2004 911 predates all this TPMS silliness, so I don't know what Porsche does these days. As I mentioned, GM uses a single receiver, and (if relearning is done properly at rotation), they report individual pressures at each corner. If I were being pedantic, I'd take issue with "many/most" and say there are a lot more GM cars out there then MB's and Porsches.:smile:

If it were fleet-wide, sure, but it doesn't seem to be. We've had two GM vehicles with TPMS and neither attempted to correlate a wheel with a location. GM's also more likely, IMO, to cheap out and do something in a way that's confusing for owners than Tesla, MB, or Porsche.

 

[CSFTN]

BMW also only gives you a red/green, but for each wheel independently. Meanwhile, if you know how to hack into the computers (or you live outside NA) you can see the actual pressure and temperature. I'd guess Tesla uses the same sensors, perhaps only has 1 receiver, but the computer probably knows the 4 tire temp.s and pressures.

 

[Hank42]

..yay, another TPMS thread.

TPMS are new-to-me, and somehow I've managed for the last 30 years w/o them.

I think Tesla has struck a good balance of information on TPMing: only show if there's a problem. Tire pressure will change with temperature, and altitude. Showing raw pressure data fluctuating would freak some A-type people out who would undoubtedly begin modifying their driving style to compensate in order to keep the tire pressure in the "sweet zone" of pressure for maximum range.

...or, it would get old fast.

Get off your duff and figure out which corner is complaining.. and while you're at it, check the condition of your tires. I've heard people here being "surprised one day" to find they've driven rear wheels down to the metal cords. Now, that's out of touch!! Blame it on some missing sensor that didn't detect tread depth for you? Metal shard detector? Rubber bulge detector? Put down the devices and check the physical world sometimes.

Next, people will want to know battery pack temperature or something on the display all the time...

I'm sorry I even mentioned that just now. Expecting thread on that soon.

Hi Scott!

Some great points there - I agree with all of them. I guess the gist of this TPMS thread is that if you're gonna engineer in a system, then do it whole-assed, not half-assed. To your point of being more in touch with the car and checking things for yourself - you are spot on - I'd almost prefer the car did NOT have a TPMS, because then I'd have to check manually. But since there is a TPMS, then it should at least offer up more information.

 

[stevezzzz]

I had a TPMS low pressure warning pop up this morning, and for the first time in my experience it reported which tire was low. Huzzah!

I've got the new 2014 sensors on my P85D running firmware 6.1 (.167).

 

[frosken]

I had a TPMS low pressure warning pop up this morning, and for the first time in my experience it reported which tire was low. Huzzah!

I've got the new 2014 sensors on my P85D running firmware 6.1 (.167).

That's the first I've heard of Model S telling you which tire is low. Awesome! How did it let you know? Do you have any photos?

 

[FlasherZ]

This should probably be merged with:
TPMS - Low Pressure - Why Not Tell Us Which Tire?

A description of why it might be difficult to trust which tire is which:
TPMS - Low Pressure - Why Not Tell Us Which Tire? - Page 3

Photo is two posts down from that one.

 

[stevezzzz]

Here's the warning I got. The front right tire measured about 38 psi, so it seems to be accurate. Pardon the dusty screen: I just got back from a road trip to the Sonoran desert.

[Update: there was a tiny metal sliver in the tire leading to a slow leak.]

 

[JPP]

Here's the warning I got. The front right tire measured about 38 psi, so it seems to be accurate. Pardon the dusty screen: I just got back from a road trip to the Sonoran desert.


View attachment 73310

[Update: there was a tiny metal sliver in the tire leading to a slow leak.]

...nice to see the new message...wonder if the old sensors/builds can/will display this info. Also wonder how the system gets calibrated to indicate what tire/wheel is the issue (assuming that the TPMS reset button on your touchscreen looks like mine).