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...the message I got when I was transporting a pair of wheels with tires mounted complete with TPMS. I found it amusing.
Maybe one of the tire sensors is transmitting intermittently, but too rapidly for the computer to process. Going by the delay in the displayed changes when adjusting tire pressures I think the sensors normally transmit maybe once a minute or thereabouts.
But, then why doesn't this pop up when you pull up to a Porsche at a red light?
I guess that Porsche is trying to discourage you from modifying your Cayman to this configuration.

Quote
Guenter in Ontario
I guess that Porsche is trying to discourage you from modifying your Cayman to this configuration.


That car came to my mind too. I don't think they had TPMS.grinning smiley
Does this happen when your are amongst other TPMS equipped vehicles??

MIKELLIG
Probably not because the range of the sending units is very limited.
... TPMS reset mode was engaged with more than 4 active senders in range you'll get the displayed message.
Happy Porscheing
Pedro

Pedro Bonilla
1998 Boxster 986 - 299,000+ miles: [www.PedrosGarage.com]

PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)



Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

I'm guessing that's where they'd have to be to get individual readings for each wheel. And, the range would have be pretty limited to avoid getting reading from nearby wheels during the reset mode.
I wonder if Guenter may have been referring to the unit(s) which receive the signal transmitted from the sensors in the wheels? (assuming the sensors inside the wheel send a signal).
Yes
Guenter in Ontario - 5 years ago
Wondering about the sensors that receive the info and pass it on to the computer and instrument display.

I know it's a more sophisticated than in the BMW system which only tells you there's a problem with a tire. You have to determine which one.
[en.wikipedia.org]

According to the first paragraph here, Porsche uses a central receiver:
[porschetpms.wordpress.com]

Scroll down a bit at this link to where the illo is. Alex K's second paragraph claims Porsches have receivers near each wheel:
[forums.teslamotors.com]
(Not sure how Alex K arrived at this. Perhaps because each tire position is identified.)

Oh, well. At someone's next official servicing that dealer might be willing and able to answer authoritatively.



Edited 1 time(s). Last edit at 02/29/2016 08:36PM by Laz. (view changes)
I agree that the Porsche system must have a cental receiver. I think all the systems need that so a tire fault can be detected and a warning given.

I believe the BMW system is a sample of the simpler system. With use of a sensor it measures the tire rotation speed at each wheel. (I picture it like the sensor on a bicycle wheel to measure speed.) If one wheel is rotating more quickly than the others, it would indicate a loss of tire pressure because the diameter of the tire becomes smaller. So you get a warning that a tire has lost some air. There's no indication which one it is. I don't think there's a battery powered wheel sending unit in the BMW system. At least we haven't had to replace one in the 7 years we've had the car.

The Porsche system is more sophisticated. The wheel sensor reads the actual air pressure and sends it via radio frequency to a sensor (I think it would need one in each wheel well to differentiate between the wheels). This sensor sends it to the central processing unit and the readout on the dash. I find it much more useful then the BMW system. That's why the sensors have to be replaced in the Porsche system and not in the BMW system.
It seems it this case there's a central "control unit" (not a receiver) in the front trunk, near the brake fluid reservoir:
[blog.obd365.com]
[rennlist.com]
Here's a pretty good description of what could be applicable to Boxsters and 911 variants:
[www.insanegarage.com]
I think the trigger is a direct-wired intermediate step that amplifies the weak radio signal coming from its associated tire sensor, thus allowing the sensor's battery life to be conserved.



Edited 2 time(s). Last edit at 02/29/2016 09:28PM by Laz. (view changes)
I don't think it's necessary to disconnect the system to save the batteries. I believe when the ignition is switched off. The wheel sensors are designed to go into "sleep" mode and stop sending data to save the batteries.
And letting the wired-to-the-car's-electrica-system triggers use their externally supplied energy to relay the signal over the relatively longer distance. (Square of the distance and all that.)
This quote is from the 2013 981 Service Information document (which is a 186 page description of the various systems - in the M-B world it is called a model year introduction manual).

With the Tire Pressure Monitoring system (TPM Generation 2.6), the tire pressure of
the running tires is monitored permanently and separately for all four wheels. Compared
with the TPM Generation 2.3, which was installed in the Boxster as of model
year 2009, the antenna in the new TPM Generation 2.6 is now integrated in the control
unit and installed in the underbody area between the coolant pipes. The basic
functions have not changed.
Just glossed through it, and it looks pretty informative:
[www.callasrennsport.com]
apparently in an (unsuccessful) effort to limit the weight gain.

Speaking of weights, my local Porsche dealer tells me there's already a wait-list for the 718, and they're giving deep discounts on remaining 981's.







BTW, tomorrow is April 1, right? grinning smiley
"I never tell the truth. Do you believe me?"
My dealer is giving 75% off all remaining 981 Boxsters.

You should check out the huge 2016 Boxster inventories. Too bad you jumped the gun and bought one of those obsolete NA Boxsters with their aweful noisy exhaust that chews up tires and hurts your face.
Quote
Laz
Just glossed through it, and it looks pretty informative:
[www.callasrennsport.com]

Great article. That confirms everything I had mentioned in my other post, including the individual sensors / receiver antennas in each wheel housing for the Direct system.
Quote
Guenter in Ontario
Quote
Laz
Just glossed through it, and it looks pretty informative:
[www.callasrennsport.com]

Great article. That confirms everything I had mentioned in my other post, including the individual sensors / receiver antennas in each wheel housing for the Direct system.

After re-rereading the article, I see that the Indirect system uses the ABS sensors to detect differences in wheel spin speed. No batteries or transmitters required, but also doesn't give as much information as the Direct system that Porsche uses.
not as useful as the Direct system.

As the article says, the Indirect system is also more prone to false readings. That happened once as I was driving the BMW on I-26 a few years ago. The road surface was uneven due to construction. Got a TPMS warning in an area where there was no place to pull over. Car seemed to be handling normally. I drove about 10 miles and got off at the first exit. Check all four tires and they were all in the correct pressure range. I reset the system and no more warnings.
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