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Discussion Starter #1 (Edited)
TPMS - What I've learned and findings...

Well, here goes my first big thread on this forum. I have spent countless weeks searching for answers to questions regarding TPMS and new rims. I bought a new 2008 FJ in Sandstone last October. In the deal I negotiated with the dealer, I had him substantially discount a 5 rim set of TRD rims for it. I didn't want the extra package because at $1899 I figured it would be cheaper to just get the rims and wheels myself and in the meantime keep the factory rims as a nice set for winter or longer trips.

Anyway, nowhere have I been able to find a definitive answer on anything regarding turning off TMPS on the FJ or what the law actually calls for - in regards to my new rims. So based on some threads here I decided to just live with the light and get some BF Goodrich All Terrain tires for the TRD rims and just put in some "normal" valve stems. I got a good deal at Costco for the tires, however they refused to put them actually on the vehicle without having a TPMS sensor for each of the new tires. I figured that was a total bunch of bunk, but they refused. So I had them mount the tires and not put them on the FJ and I said I would put them on myself. They were sorry the whole thing, but they said it was the law that wouldn't allow them to actually put them on the vehicle. I did get the tires on the rims... just not actually placed on the vehicle.

Which brings me to this post and what the ACTUAL requirements of this law are and what poor analysis was done on behalf of our gov't. Now I'm no lawyer, but this is just my observation on what I've been reading.

You can find information regarding the TPMS law here:
Federal Motor Vehicle Safety Standards; Tire Pressure Monitoring Systems; Controls and Displays
NPRM on TIRE PRESSURE MONITORING SYSTEM FMVSS No. 138

WHAT TRIGGERS TPMS in my FJ?

First, it appears that the monitoring system in the FJ (as per my observation as well) only lights up when any tire falls below a 25% value of the correct tire pressure for the tire. In other words, if your TPMS system is calibrated for 40psi per tire, it will only light up when any tire is under 30psi. There is no comparison between tires with this system. So, if you are looking for new rims or new tires that have a different PSI requirement, be aware that if the new requirement strays from the delivered value on your current TPMS, you may have to go to the dealer to have them recalibrated - which I understand they can do.

Here's an excerpt from the above link(s):
"Overall, we tentatively conclude that the 25 percent threshold adequately captures the circumstances at which low tire pressure becomes a safety issue. We also believe that this level would be acceptable to most drivers and would not be considered a nuisance to the point that it would be ignored by large numbers of drivers. We also believe there is no reason to examine higher thresholds (e.g., a 30 percent threshold), since they would provide fewer benefits for similar costs."

CAN I DISABLE TPMS?

The short answer appears no - at least not by any concoction of turn ignition on, push this button, blah blah blah. I would guess you would have to somehow disable the system by your own means - physically. In this case, from what I've read you may be causing yourself issues later down the line if you want to sell the vehicle or need to pass an inspection. Some states, I read, now require that for your 2008 and beyond vehicle to pass inspection that you must also pass a TPMS test. If you don't and fail and you will have to pay to get it up to inspection standards. Just an FYI depending on the state you live in.

According to the NHTSA:
"We continue to believe as a general matter that it would be inappropriate to permit any manual or automatic disablement of the TPMS. However, should the unusual events cited above occur, manufacturers would be required to alert the driver regarding impairment of the TPMS through a system malfunction warning."

What I conclude from this: there is no way Toyota will ever be able to offer an option to manually override the TPMS like you can for say, a passenger airbag.

WHAT DOES THE GOV'T THINK THE COST IS?

In reading the TMPS standards, it appears that the gov't estimates that the total cost to implement a system on a NEW vehicle is around the following (this is on the NHTSA site, but here are the figures):

"The costs of the Beru direct measurement system are broken into the following categories (1 control unit at $44, 4 wheels electronic modules to measure tire pressure and transmit the data at $32, 4 reception antenna at $11, 4 valves at $7, the instrument panel display at $2, assembly and miscellaneous costs at $10) for a total of $106.

The costs of the SmarTire direct measurement system are broken into the following categories (1 control unit which includes one antenna at $30, 4 wheels electronic modules to measure tire pressure and transmit the data at $30, 4 valves at $5, the instrument panel display at $4, assembly and miscellaneous costs at $11) for a total of $80.

The costs of the Johnson Controls direct measurement system are broken into the following categories (1 control unit which includes one antenna at $19, electronic sensor modules in the 4 wheels to measure tire pressure and transmit the data at $30, 4 valves at $7, the instrument panel display at $4, assembly and miscellaneous costs at $9) for a total of $69.

...

Based on the three direct measurement systems costed out in the teardown studies, the average price for the tire pressure sensors is about $7.50 per wheel or $30 per vehicle. "

NO WHERE have I seen that it would be that cheap to put additional sensors on my tires. I looked around and the cheapest I could find was about $90+ dollars at an online dealer - for EACH sensor. For 5 tires that brings it up to $450 just in sensors - no where near the $30 in the gov't report.

Factor in also that the TPMS sensors only last 5-7 years based on their battery life - and I understand that battery replacement is not an option - you must get new sensors. So, in this case, I am a little bit ticked that it is costing so much. If it WERE $30 for my vehicle to get them, you can bet I would have.

OTHER THOUGHTS.

Now, I'm not going to say that the data on the NHTSA website is wrong with the facts regarding fuel savings and potential injuries/lives saved per year and what not. I read all the facts. I'm not saying there isn't a benefit. However, the cost they site for this benefit is WAY off compared to what we are seeing in the real world. I just wish this option was not so costly - after the purchase of the vehicle.

Additionally, I've read on some threads that Toyota will store up to two sets of tires/rims in the system? Can anyone confirm this? I would think it would need to hold two sets of tires/rims with 5 tires being in each set for a total of 10 TPMS sensors. 4 per set is just not going to cut it.

Anyway, those are some extra thoughts on this topic and some sources for you to read up on if you are interested. If you have any other thoughts please post.
 

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Nice write up.

Isn't the NHTSA a govt' agency?

"However, the cost they site for this benefit is WAY off compared to what we are seeing in the real world. I just wish this option was not so costly - after the purchase of the vehicle."

If that surprises you, read the tax code...
 

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Nice write up.

Isn't the NHTSA a govt' agency?

"However, the cost they site for this benefit is WAY off compared to what we are seeing in the real world. I just wish this option was not so costly - after the purchase of the vehicle."

If that surprises you, read the tax code...
The cost they cite is the estimated cost to the automaker, once implemented in large-scale manufacturing, not the end-user for a replacement part
 

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Discussion Starter #4
The cost they cite is the estimated cost to the automaker, once implemented in large-scale manufacturing, not the end-user for a replacement part
$30 estimate vs. $450 actual seems a little ridiculous to me. And in 5-7 years when these things start giving out and consumers will need to replace them - I think the hight replacement cost will be quite a surprise to a lot of people. I don't argue with the fact that large scale manufacturing reduces costs. The agency though uses that same cost to justify the law given how much they deem a human life is valued at vs. the cost of putting these on 30 million cars a year.

I just think the numbers they use are a bit like pulling values out of thin air to justify the law. And if these supposed values are coming from the suppliers of the parts, then why such an outrageous markup - even after going through a middle man like the dealer?

You may not see the backlash now because new owners may not care about the system because right now as it seemingly works. Wait until a warranty runs out and they malfunction though - then see how many people start complaining. Either that or the costs had best come down to $30 for a set of tires in the next 3-5 years.

As an aside, I removed all my tires and put on the new ones - without sensors - and no warning light. The warning light did come on this past weekend though with my original set when I went to the dunes and aired down so I know it does work. I drove around town today with the new tires on and nothing. I'll let you know what happens and if the idiot light ever comes on in the future.
 

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Can you recalibrate it?
From what I understand the sensors can be recalibrated for a different pressure level. However, every place I checked with said it was something that a dealer would have to do. It does appear though that you can get this done.
 

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$30 estimate vs. $450 actual seems a little ridiculous to me. And in 5-7 years when these things start giving out and consumers will need to replace them - I think the hight replacement cost will be quite a surprise to a lot of people. I don't argue with the fact that large scale manufacturing reduces costs. The agency though uses that same cost to justify the law given how much they deem a human life is valued at vs. the cost of putting these on 30 million cars a year.

I just think the numbers they use are a bit like pulling values out of thin air to justify the law. And if these supposed values are coming from the suppliers of the parts, then why such an outrageous markup - even after going through a middle man like the dealer?

You may not see the backlash now because new owners may not care about the system because right now as it seemingly works. Wait until a warranty runs out and they malfunction though - then see how many people start complaining. Either that or the costs had best come down to $30 for a set of tires in the next 3-5 years.

As an aside, I removed all my tires and put on the new ones - without sensors - and no warning light. The warning light did come on this past weekend though with my original set when I went to the dunes and aired down so I know it does work. I drove around town today with the new tires on and nothing. I'll let you know what happens and if the idiot light ever comes on in the future.

EIther they put the old sensors back on or the system light is malfunctioning-- it won't work without sensors, so it wouldn't know that you aired down.
 

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Nice post...actually I have been browsing all of them but have not seen the answer to the question I was looking for. Several weeks ago I was at Discount Tires and was told that if I ran my FJ without the sensors, not only would I have the light come on, but it would eventually fry my car's computer...doesn't sound right to me and I'm naturally suspicious of any type of car shop...can anyone confirm or deny?
 

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Re: TPMS - What I've learned and findings...

As far as battery life goes...and I'll probably draw fire here.

The TPMS we used at Ford Motor Company (I worked at the Atlanta Assembly Plant) did not use batteries for the sensors. Rather the sensors used voltage induced by the radio transponder to produce a signal. In other words the "monitoring piece" sends out a radio signal and this radio signal induces a voltage in the valvestems powering the valvestems electornics to send a reading.

Additionally, the valave stems (at least on the Fords) where not excited until around 15 miles an hour.

There should be no batteries in the valve stems.

Induced voltage is widely used in this type of applicaiton. Have you seen the wireless charging stations? That's induced voltage. Ever brought something home from a store and had to remove a sticker that contained an odd spiral shaped piece of metal? That was an anti-theft tag that uses induce voltage. Hell, we used induced voltage to keep track of cars on the assmebly line. It's old technology. No batteries required.

I don't know anything about how the Toyota's are built. But I'm willing to bet TPMS uses induced voltage.
 

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Nice post...actually I have been browsing all of them but have not seen the answer to the question I was looking for. Several weeks ago I was at Discount Tires and was told that if I ran my FJ without the sensors, not only would I have the light come on, but it would eventually fry my car's computer...doesn't sound right to me and I'm naturally suspicious of any type of car shop...can anyone confirm or deny?
THEY ARE CORRECT!!!!!

It will fry your computer if you also send a grounded 220 Volts through your system while your car is bathing in a lake upto the windows..........:flame:

I ran my 4R for a year with only 4 Sensors, spare had a bad sensor, and I already got scammed paying $125 for a replacement sensor get this "BECAUSE OF A DAMAGED VALVE STEM" couldn't find a SHOP to rebuild the valve stem without the new sensor!!!!!! BUREAUCRACY is for the LAZY I am convivnced.

Anyway, so finally replaced the second sensor (spare wheel) sensor and after light didn't go off, because I was told the STEALERSHIP would have to assign the sensor to the control unit I decided I WILL NEVER REPLACE ANOTHER ************* TPMS SENSOR AGAIN!!!!!!!!!!!!!!!!!!:wave:


Ok now off to confession and Mass :bigthumb:
 

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I can't stand this stupid light or this idiot sensor system. I bought an extra rim for an second spare for off road expeditions and I cannot carry the extra tire every day with me. It was not a problem until I rotated the tires and the extra is on the truck and the sensor rim is on the original in the garage. I just want to disable the damn thing. There must be some way to just get rid of the light. Time to break out the schematics.

I know that removing those three wires from the console got rid of that stupid ding-ding seat-belt/door-open warning light system in the dash. There must be a way to just turn the light off for tpms. Maybe we can find the sensor, or the leads and just disconnect the indicator.

BTW, I had a sidewall blown out on rocks with the original crappy street tires that came with the FJ. I ran the truck for 18 months without replacing it and the light was glowing the entire time. Nothing ever burned out or fried the computer.
 

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I hate these. This has to be the stupidest thing the government has come up with to add to cars.
 

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Thanks for posting! I love this forum. I don't even have to ask a question. The answers are already here!

My 2008 FJ has the TPMS warning light on. I am 99.9% sure it is the spare tire that is going low. When I bought the vehicle the dealer filled my tires because the warning light was on and the one that was low, was the spare. I am very close to buying my Lift Kit ( with in a week) and tires and rims will be next. It sounds like the best solution based on all the posts is to see if I can get my new tires to come without the sensors. I saved the thread on how to disable the warning light. So when the BF ( @MAD MIKE ) comes home in September, we can do this together. His is a 2007 FJC without the TPMS.

Sorry everyone to resurrect this thread from the dead. I find that when I am trying to get the BF to a certain thread, this seems to be the easiest for me.
 

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Update: so I was partially correct. My spare was low, 21 psi. However , so where both front and rear Driver side tires. They where also sitting at 21 psi. So until I can get my tires and rims replaced, the TPMS will come in handy. I am only slightly relieved to see other tires going low. Only because I now know there is an issue with my other tires. I was really dreading all of my tires being fine and my spare having the slow leak and the TPMS Warning light staying on all the time. I think that sometime in September will be a mod day!
 

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You do realize you can swap your TPMS sensors between wheels? If you replace your rims, just move the sensors to the new ones.
Nope had no clue! Thanks for the info! :wink
 
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