My S does not have them. Neither does my mom's Civic.
You can find more information on our web, so please take a look.
My wifes Acura RDX does have them.
Many first-generation TPMS sensors are beginning to retire, or simply die of old age. This should lead to an uptick in consumer awareness of these systems, and an increase in related service work for your shop.
Tires have been subject to flats, punctures and blowouts since the advent of the first pneumatic tires in the late s. Bicyclists and, later, motorists learned to check tire condition and inflation often by squeezing the tire or eyeballing its profile. Actual pressure gauges were originally so expensive that only professionals could afford them. Mass production of later stick-type gauges rendered them cheap enough that today almost every car has one&#;sitting unused&#;in the glovebox!
The debut of the Porsche 959 heralded the first reported passenger car tire pressure monitoring system (TPMS). It incorporated a hollow tube within one spoke of the rim. Other high-end European luxury cars followed suit, and by , the Renault Laguna had become the first high-volume midsize passenger vehicle sporting TPMS as standard equipment.
Fast forward. Beginning with the model year, cars and light trucks carry a mandatory tire pressure monitoring system, usually consisting of direct-reading pressure sensors installed in each road wheel. Some also carry sensors in their spare tires, although these are not specifically required by law in the case of temporary (compact) spare tires. By , the share of TPMS-equipped vehicles on the road is expected to reach 38%.
As a recent National Highway Traffic Safety Administration (NHTSA) report notes, &#;Proper tire inflation is important for several reasons. Underinflated tires experience a greater amount of sidewall flexion than properly inflated tires, resulting in decreased fuel economy, sluggish handling, longer stopping distances, increased stress to tire components and heat buildup that can lead to catastrophic failure of the tire, such as cracking, component separation or blowout. These catastrophic failures can cause loss of vehicle control and may result in a crash. Overinflated tires may be more easily damaged by potholes or debris. Severe overinflation may increase stopping distance due to reduced area of road contact and nonoptimal traction, and may also contribute to vehicle instability. As with underinflation, overinflation may result in uneven tread wear that reduces the useful life of the tire.&#;
As you might expect, safety&#;their middle name!&#;is of paramount concern to the NHTSA folks. That&#;s a blessing, because if it were only about the fuel saved, the same report concludes that the average driver of a TPMS-equipped car would save a whopping 9.32 gallons of gas in the first eight years of operation. The numbers are slightly more compelling for light trucks: 27.89 gallons over the same eight-year period. Either way, it&#;s hard to justify the cost in terms of fuel savings alone, so you have to factor in both decreased tire wear and the putative safety benefits to come even close to an economic break-even for TPMS.
Five years ago, accidental breakage accounted for the vast majority of TPMS sensor replacements. But now, many of the first-generation sensor batteries have begun to fail, accounting for the majority of current sensor replacements. Most sensor batteries cannot be successfully replaced independently of the sensor, as the batteries are typically encased in a moistureproof potting material. (While it would be theoretically possible to melt out the potting material, solder in a new battery and repot the sensor, it would be economically prohibitive vs. simple unit replacement.)
With a projected battery life span of six to ten years, expect to see an ever-increasing number of such failures in coming years as the pool of aging sensors increases. To put that concept into perspective, consider this: Total U.S. car sales during totaled around 14.5 million units. Projecting future replacement needs some six to ten years out, and allowing for some attrition due to accidents and other factors, last year&#;s vehicles alone will eventually result in the need for some 50 million TPMS sensor replacements.
What&#;s your share? There are roughly 175,000 automobile service facilities in the U.S., some 10% of which are new-car dealership service departments. If the work were all done and spread out evenly, every shop in the country would expect eventually to replace around 300 sensors per year. With wholesale prices ranging from a low of around $25 to a high somewhere north of $80 per sensor, this represents a significant market. A quick survey of retail prices in my local area netted quotes from $20 to $50 per tire for labor on top of parts. This included mounting, balancing and any necessary reprogramming or relearning services.
Of course, under current law in most jurisdictions, consumers are not required to repair or replace TPMS sensors or systems in the event of failure, so some percentage of those anticipated replacements may never occur (but, see &#;Legal Issues&#; on page 26 for an important caveat). If you think those numbers make a compelling case for getting serious about TPMS work, consider this: We&#;re fast approaching a population of 100 million TPMS-equipped vehicles. That means that somewhere around a quarter to a third of all vehicles serviced are currently equipped with TPMS. The numbers and percentages will rise from here.
If one sensor battery quits, are the others far behind? Given the tight uniformity of modern manufacturing, odds are that a battery failure in one sensor is likely to be followed by three more in fairly rapid succession. At the very least, group replacement becomes a prudent suggestion if the tires are nearing the end of their useful life as well.
Some sensors will report current voltage and/or remaining battery life percentage in datastream. This information, along with information as to driving habits, can allow you to tailor your service suggestions appropriately. In general, most vehicle manufacturers&#; monitoring algorithms consume less battery power per mile or per unit time under highway driving conditions than during stop & go driving. A remaining battery life of, say, 10% might be enough for two years of mostly highway driving, but perhaps only a half or even a quarter of that time in city driving conditions.
Direct-reading sensor systems (dTPMS) are those that rely on integral batteries, sensors, transmitters and associated circuitry. While the role of the main components is clear, the &#;associated circuitry&#; may hold a few surprises. Most such TPMS sensors incorporate circuitry specifically designed to preserve and extend battery life. Using motion-sensing circuitry allows the pressure sensing and transmitting circuits to be switched off when the vehicle is stationary. Additionally, since federal regulations require that the system update at least every 20 minutes, each wheel sensor is potentially allowed to sleep for up to 19 minutes at a time, if the manufacturer so chooses. In practice, few manufacturers stretch the reporting interval that far, but it&#;s not surprising to see update rates of three to ten minutes.
The earliest indirect-reading TPMS systems (iTPMS) relied on ABS wheel-speed sensors to detect any wheel consistently spinning faster than the others. Since an underinflated tire has a slightly shorter running circumference, it has to go more revolutions to cover the same road distance. However, these early systems were not good at noticing when all the tires were equally low, as typically happens when colder weather sets in (see &#;Shrinkage! The Combined Gas Law of the Temperature/Pressure Relationship&#; above). This shortcoming led most vehicle manufacturers to abandon this technology in favor of the more expensive direct-reading type.
Further research has revealed, however, that certain wheel-speed signal characteristics are highly sensitive to tire pressure. This allows some newer indirect-reading systems to incorporate the ability to analyze certain frequencies, spectra and other features of the wheel speed sensor&#;s signals with sufficient certainty to detect reduced inflation in as many as all four tires. In such cases, the TPMS function is handled by the ABS/VSC control module.
Most such second-generation iTPMS applications rely on a push-button or menu-selected manual reset procedure to reinitialize system response to variations due to tire brand/replacement, construction and wear, as well as individual driving styles and speeds. The reset procedure may require data acquisition over time periods as long as an hour before the system has fully learned the signal characteristics. In many cases, even a simple tire rotation will require a reset, as the signal characteristics for a given tire and wheel may vary, depending on mounted position.
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Direct-reading sensors incorporate batteries and other toxic materials which should not be disposed of in the normal waste stream. Incineration releases toxic fumes, while heavy metals and rare-earth minerals will eventually leach out under landfill conditions, potentially contaminating both soils and groundwaters. Some municipal, county, regional or state agencies accept TPMS sensors for dismantling, recycling and appropriate disposal under the same programs governing general electronic waste, so you should check those options first.
If no other option is available, it&#;s easy enough to break most sensors apart to remove at least the spent batteries which can then be recycled along with all the other button-cell units you replace in customer key fobs. Remaining electronic components can be recycled with other post-consumer electronic waste materials. Customers respond very positively to such efforts, so be sure to let them know the part you play in the industry that&#;s the world&#;s largest recycler.
Recently, the Tire Industry Association (TIA) asked NHTSA for clarification on several TPMS scenarios. Try your hand at answering each of these before reading on:
Already broken. Your customer complains of a flashing TPMS light, and you determine that one of the sensors, incorporated into a valve stem, is faulty. The customer declines to replace the faulty sensor. Is it legal for you to replace the faulty sensor with a conventional snap-in rubber valve stem? Does your answer change if the sensor in question also leaks?
Winter wheels. Your customer purchases a set of winter tires and rims for installation on his TPMS-equipped vehicle. The winter wheels are not equipped with TPMS sensors. Is it legal for you to install them? Does your answer change if his TPMS light is already flashing with his regular tires on?
Oops. In the course of other work, you inadvertently damage a previously working TPMS sensor, rendering it inoperative. You cannot procure another sensor before the close of business. Is it permissible to put in a standard valve stem and allow the customer to take his vehicle? Does your answer change if you make an appointment with the customer to return for the new sensor on another day?
Dang. After performing some service work, you return a car to your customer with the TPMS light off, but it comes on after being driven for 15 or 20 minutes. Are you guilty of violating NHTSA regulations? Does your answer change if an illuminated TPMS light was the customer&#;s original complaint? How about if the light was not illuminated previously?
The regulations which require TPMS also prohibit knowingly making such a system inoperative. A recent letter from O. Kevin Vincent, Chief Counsel for NHTSA, addressed each of the scenarios above as posed by the TIA. Some of the answers may surprise you.
Already broken. Since the sensor is already inoperative, you may replace it with a standard valve stem. It doesn&#;t matter if the original sensor is leaking or not. Either way, you will not knowingly be making the system inoperative; it already is inoperative.
Winter wheels. NHTSA says you must decline to install the wheels. It specifically rejects the argument that since the TPMS light would thenceforth be on, the system would still be operative. You would be guilty of making the system inoperative. If the system were already inoperative (TPMS light flashing), would you knowingly be making it inoperative by installing the wheels without sensors? Looks like their answer would still be not to get involved, although this particular circumstance was not discussed.
Oops. The regulation prohibits &#;knowingly&#; making the system or a device or element of the system inoperative. NHTSA&#;s general stance is that accidental, negligent or inadvertent damage is not included in &#;knowingly&#; making the system inoperative. May you return the vehicle to your customer? Yes, unless you &#;knowingly&#; made the system inoperative. In that event, you may allow it to be used solely &#;for testing or a similar purpose during maintenance or repair.&#;
Dang. Once again, unless you have &#;knowingly&#; made the system or some element of it inoperative, you&#;re not guilty of a regulatory infraction. Of course, if an inoperative TPMS was the customer&#;s original complaint, you can expect some unhappy fallout. And if it wasn&#;t the original complaint, you may at the very least want to add an inflation check to your final inspection routine.
Well, how did you do? I have to admit that some of the answers surprised me, at least a little. I was pleased to learn that no one is going to force consumers to make repairs to a system that is, in the final analysis, merely a reminder to check tire pressures. As to the snow tire question, my own experience has shown that the folks who are most likely to spring for an extra set of winter tires and wheels are also the most likely to keep up with pressure checks in the winter, regardless of whether their cars have TPMS. So the idea that I shouldn&#;t install their winter wheels struck me as showing perhaps more concern for the letter of the law than for the reality of the increased driving safety a set of good snows can offer. Still, you can&#;t win the argument, so you might as well accept the reality: If the TPMS system is in good working order when the vehicle arrives, it should still be when it leaves.
The TPMS sensor replacement market is poised for major growth. Most customers will respond to a lit TPMS light, at least checking with you to see if a simple pressure check and adjustment won&#;t make things right. A light that stays on or one that flashes is likely to make most customers uncomfortable enough to spring for a new sensor, at least the first time around.
The legal issues are fairly straightforward, so play it straight. While NHTSA has not announced plans for random checks or undercover sting operations, these remain within its potential range of action should field data indicate that they&#;re needed.
A fairly simple checklist is all you need to ensure that you stay on the side of the angels. While the technical details vary by year, make and model, the overall principles remain the same for all vehicles.
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