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Does anyone have a confirmed non-functioning TPMS unit ? Inside such a unit, if it is like any other radio wave emitting device, should be or could be, an FCC ID. If there is one inside we can look it up and find the frequency(ies) it is broadcasting on. The next step would be to find the others in the set and do the same. Then an intermediary black box could be built to go from a current, read that cheap, TPMS back to the C4 unit.
I realize that the black tape method is easy and cheap to fix a light, but for a shop that breaks a TPMS unit it would be a viable product as well as folks who do want to keep the system functioning.
Based on some research I did today resulting from a comment another board member made, I found out that it is illegal for a shop to release your car if they break a TPMS sensor. They have to source and acquire such. They will argue, but that is what the law is interpreted to say. The law says the car cannot be allowed to leave the premises if they break it.
Are you talking about the unit that straps around the wheel? You do not have to open the unit. they will each have a label that shows (I believe) the FCC ID along with the position on the car the particular sender is for. Sorry this isn't rotated properly
Perfect. If I am understanding the results correctly, that was an oem piece from a 1991. But it probably chains to them all.
That one runs in the 355 mhz range. Now we know the range for that color to capture the signal for analysis. The next step if a person was going to figure something out, would be to get a working one, put it on a tire balancer machine and capture what is being sent as the wheel rotates.
I do believe the older systems found in the Corvette and Porsche are excluded from this rule, as they were not a mandated safety item at the time of production.
The problem isn't the TPMS act per se. It is 49 usc 30122(b) "Making safety devices and elements inoperative" that would catch them. Just because they were mandated after 2007 doesn't change the fact that they are a safety device.
This PDF is just one version of the email that was relayed back to the industry by the government dept.
But it could be argued as you say
This falls under the NHTSA’s guidelines that prohibit “manufacturers, distributors, dealers or motor vehicle repair businesses from knowingly making inoperative, in whole or in part, any part of a device or element of design installed on or in a motor vehicle in compliance with an applicable motor vehicle safety standard.”
Seeing that it was after they were built that the Act was enacted.
What I find interesting, is in the 1996 Owner's Manual it says:
Here are two situations that cause the SERVICE LTPWS
light to come on and stay on. Both of these situations are
normal and do not indicate that anything is wrong with
your Corvette.
1. You turn the ignition on three times in a row within
half an hour without moving your Corvette. The light
will then come on every time you turn the ignition
on until you move your Corvette.
2. You run your Corvette three times within half an
hour while all four sensors are missing. (All the
sensors would be missing, for example, if you put
different wheels on your Corvette without
transferring the sensors.)
If you would like to clear the SERVICE LTPWS light
from your Driver Information Center permanently, see
your dealer.
The part in bold is what I found interesting. GM telling you the dealer could turn off the light. SO, is there some forgotten code in a Tech2 that would turn it off ? Thus negating the need to use tape, pull the bulbs, buy extremely expensive used units. etc.
Lawyer disclaimer: I added the 1 and 2 for the points being presented, originally in the manual (online or paper, they were dots for "bullet points") when I copied the text, I lost that feature, so I made the character leftover a 1 and a 2.
The problem isn't the TPMS act per se. It is 49 usc 30122(b) "Making safety devices and elements inoperative" that would catch them. Just because they were mandated after 2007 doesn't change the fact that they are a safety device.
This PDF is just one version of the email that was relayed back to the industry by the government dept.
You are picking and choosing certain words.
The provision “prohibits manufacturers, distributors, dealers, or motor vehicle repair businesses from knowingly making inoperative, in whole or in part, any part of a device or element of design installed on or in a motor vehicle in compliance with an applicable motor vehicle safety standard.”
At the time when Corvette started installing LTPWS in 1989, it was not a "Safety Standard" mandated to all vehicle manufacturers.
That is the statement where I said what you said could be correct.
But it could be argued as you say
This falls under the NHTSA’s guidelines that prohibit “manufacturers, distributors, dealers or motor vehicle repair businesses from knowingly making inoperative, in whole or in part, any part of a device or element of design installed on or in a motor vehicle in compliance with an applicable motor vehicle safety standard.”
Seeing that it was after they were built that the Act was enacted.
So I wasn't picking and choosing to support one side of the argument. I was acknowledging both sides and agreeing that you could entirely correct.
We would have to have to get into 49 usc 30122(b) or other law/act on the books and see if there was any wording that included the C4 TPMS as a "safety device installed by the manufacturer" as opposed to a "safety device mandated by an Act to be installed by the manufacturer".
You know how convoluted lawyer written language can be. We both can agree that the TPMS is a safety device/system installed by the manufacturer. If there is all inclusive text in the Act it could fall into there.
But all of that is not what I was interested in. There are lots of folks, yes even C4 folks that still would benefit from having a functioning TPMS. I looked at one for an older guy who bought one on a whim after his wife passed away 2 years ago and knew nothing about them.
I was curious as to what frequency it broadcasted on, which we now know. If someone, and it is beyond me chose to go further with this and had a device to capture the signals being sent, all you would have to do is put a tire with a functioning sensor on a tire balance machine and spin it up. Capture the signal, then deflate under 25 lbs pressure and spin it up again over 25 mph. Then we would know what it was sending to the TPMS unit and a bridge could be built that could intercept the signals, or maybe there are some programmable sensors out there that could be programmed to send the applicable signal(s) and then solution would then be found.
Just kind of reverse engineering it. The original manufacturer is still around, even though they have merged with another company. I suppose I could write them and see if they still have the information and would be allowed to share it this many years out.
The other way would be to try and find the original patent nbr, do a lookup on that and see how the functioning was described. I have done that before.
The problem isn't the TPMS act per se. It is 49 usc 30122(b) "Making safety devices and elements inoperative" that would catch them. Just because they were mandated after 2007 doesn't change the fact that they are a safety device.
This PDF is just one version of the email that was relayed back to the industry by the government dept.
But it could be argued as you say
Seeing that it was after they were built that the Act was enacted.
What I find interesting, is in the 1996 Owner's Manual it says:
If you would like to clear the SERVICE LTPWS light
from your Driver Information Center permanently, see
your dealer.
The part in bold is what I found interesting. GM telling you the dealer could turn off the light. SO, is there some forgotten code in a Tech2 that would turn it off ? Thus negating the need to use tape, pull the bulbs, buy extremely expensive used units. etc.
Lawyer disclaimer: I added the 1 and 2 for the points being presented, originally in the manual (online or paper, they were dots for "bullet points") when I copied the text, I lost that feature, so I made the character leftover a 1 and a 2.
I do know that the C5 you can disable options and MIL's with the Tech2. I've turned off/eliminated Real Time Dampening after people get rid of the busted shocks and go to regular shocks I would imagine the LTPWS would have the same process in 96. I've never checked the 96.
Perfect. If I am understanding the results correctly, that was an oem piece from a 1991. But it probably chains to them all.
That one runs in the 355 mhz range. Now we know the range for that color to capture the signal for analysis. The next step if a person was going to figure something out, would be to get a working one, put it on a tire balancer machine and capture what is being sent as the wheel rotates.
That is a 93-96. All those were a white case. The 89-92 sensors are black.
89-92
LF 10098495 Green
RF 10098494 Blue
LR 10098497 Yellow
RR 10098496 Orange
93-96
LF 10161856 Green
RF 10161855 Blue
LR 10161854 Yellow
RR 10161857 Orange
The line with the date is about 1/4 of the way down on the above page. In order to find it, I had to use the FCC ID.
I realized that I could pull the FCC ID from the ones on eBay, so a black one, with orange tag, part nbr
14104394 has an FCC ID of CSH-7ZS00GMTX and indicates it is for the right rear
has a date of 1986 so it must be application date. they were working on these probably in and maybe before 1985 if the page has a May 86 date on it.
the right rear then (at least the black ones) operates at a 245.15 MHz frequency. If I could find the FCC of a white cased RR and check it, if the frequency is the same across all years, part of the solution is found
The neighbor is into radios, he built a wire antenna strung through the trees to a precise length that simulates a tower. I watched him outside trimming a little, metering it, trimming, etc. Maybe he has a piece of equipment to detect radio frequencies, I'll ask.
The object then is to find if the units are putting out a continuous signal, a pulse etc. Does it turn off if the pressure is less than 25 psi ?
So (for speaking purposes only at this point) if we can assume that both early and late model ones operate at the same frequencies, and put out a continuous signal when the speed is above 25 mph and the psi is above 25 psi, with them being such an early (in the development cycle of electronics in general) it might be possible to find one of the programmable ones and set it up to duplicate how these OEM works.
the 25/25 figures are straight out of the 1996 Owner's Manual
In lieu of testing, the patent application (if we could find it and if they were patented to begin with) will describe the action pretty close to how they function. Even having the patent id of the receiver (same caveat) would allow us to look it up and read how it was supposed to function and what it was expecting to receive.
I'll go back through the ones on eBay (there is a complete set of 4 black cased ones) and get the remaining FCC ID's and as I just typed this sentence I realized I will be able to check the white case RF above against the black case RF on eBay (assuming I can read it) and see if the frequencies are the same.
Does anyone have a broken TPMS unit ?
