Tech Update: Top 5 TPMS Questions
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Tech Update: Top 5 TPMS Questions

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From professional and college football down to youth-league soccer, everyone (including TechShop!) has a “Top Something-or-other” list. Why should the tire industry be different?

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Over the last year or so, Tire Rack has been conducting an informal and unscientific survey of its customers regarding the reoccurrence of issues dealing with tire pressure monitoring systems. Thanks to its wholesalers, service technicians and counter sales people in the field, just to name a few, Tire Rack developed a list of the Top Five Most Common TPMS Questions.

“It wasn’t anything special,” said Scott Lakin, who is in charge of Tire Rack’s product applications and development. “We developed this in routine discussions with our customers — primarily wholesalers — who receive their feedback from technicians, service managers and counter sales people.”

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Lakin and other experts at Tire Rack reviewed the questions and offered pertinent answers. With that as an entrée, but with a quick disclaimer that there are likely more than five, here are Tire Rack’s current “Top Five” questions regarding TPMS:

1. How do I reset my TPMS?

(Lakin said this question was the most popular one, and not surprisingly has the most possible answers.)

Answer: The first question should be: What kind of car are we dealing with? For example, a 2006 BMW M3 uses an indirect system, so it has one simple reset button. Once the tires are set to the correct pressure, the vehicle’s engine can be started, and then the reset button must be pushed for no longer than eight seconds. After the warning light turns off, the vehicle can be driven normally and the system will calibrate itself.

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But not all indirect systems are alike.

A Buick Rendezvous must be driven at several specific speed ranges, including 74.5-plus mph for 10-20 minutes in a straight line after pressing multiple buttons and turning the ignition key on and off a few times. After receiving your speeding ticket in the Rendezvous, you can return to your shop and decipher how to register new sensors to a vehicle with a direct system.

Some direct systems automatically learn their new sensors, like in the Acura MDX, while other vehicles must be sent to the dealership. Currently, all Hyundais, Infinitis, Kias, Lexuses, Mitsubishis, Nissans, Subarus, Suzukis and Toyotas must have their new sensors registered at the dealership. To complicate things for the aftermarket, Lexus and Toyota models must have each sensor’s ID code entered into their ECUs using a dealer-only OBD II scan tool. (To simplify the work for the customer, when Tire Rack sells a TPMS-equipped wheel/tire package for a Lexus or Toyota, they include each sensor’s ID code on the customer’s invoice and in their database so that the customer can go directly to the dealership and get the ID codes entered into the vehicle’s ECU. Still, the customer has to make a separate trip). Many vehicles are coming out with auto-learn systems or at least have initialization procedures that can be done at a tire shop or in the consumer’s driveway with minimal tools. So, on some level, the systems are becoming more user-friendly.

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2. Do I need to get my sensors re-registered after
a simple tire rotation?

Answer: Some systems that display the tire pressure at each location require a sensor re-learn procedure to be done after the tires have been moved to a different corner of the vehicle. But others use antennas in the vehicle’s wheel well to “see” where the old wheel moved. If the sensor with the ID code of 1234567 was at the left-rear location, but now the left-front TPMS antenna is reading that 1234567 ID code, then the system will update its TPMS display to correctly show the wheels and the tire pressures at their new locations. The most common system only displays a “Low Pressure” light on the dash and those systems normally don’t need to be reset when a tire rotation has been done. You may want to consult the a TPMS guide for a specific answer concerning a TPMS-equipped vehicle.

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3. How do I know if the sensors fit properly and
safely in a wheel?

Answer: This question is what causes a lot of problems for shops. With some sensor costs skyrocketing over the $200 price tag, you can’t afford to torque a sensor down in a wheel and hope it seals properly before the valve snaps. The first step is to verify if the valve hole is compatible with the particular sensor that is about to be mounted. There are more than 15 styles of valve-mounted sensors in the OE market and each one has a different sensor body shape and range of valve angle adjustability. If the chosen wheel has a valve hole mounted in the middle of the barrel (a 90° valve), we consider this wheel not TPMS compatible, since no valve sensor can be mounted in this location without being prone to damage when the tire is mounted or dismounted.

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To test a sensor’s fitment, first place the sensor’s valve through the valve hole and tighten the valve nut down by hand until the sensor is sitting level. Next, slide a piece of paper around the entire sensor body to see if it is touching or resting on the wheel. If it is touching the wheel, torque the sensor down (to specification) slowly and with caution to see if the sensor applies more and more pressure at that specific area.

If the sensor is still touching the wheel or applying more force as the torque is increased, remove the sensor immediately since that wheel does not have a drop-center large enough to handle that specific sensor design.

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However, if the sensor was not resting on the wheel after just finger tightening, you may proceed to torquing the sensor to spec with a calibrated torque wrench. Check the tolerance again after torquing to make sure the sensor body is still not applying force onto the wheel, and that the sensor is sitting parallel with the wheel barrel.

Each sensor should have a defined torque specification (which should be listed in your TPMS guide) directly on the sensor body. If not, you should contact a performance specialist. The spec will be listed in either inch-pounds or Newton-meters. The lowest and highest torque specs Tire Rack has seen range from 35 in.-lbs. (4 Nm) to 81 in.-lbs. (9 Nm).

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A valve nut torque wrench is an absolute necessity for any shop. The average retail cost of a sensor is roughly the same as the cost of a quality torque wrench. You wouldn’t guess at torquing lug nuts on a car, so why guess at torquing valve nuts?

4. Can I use a metal strap or strong adhesive to attach a sensor to a wheel if it cannot be installed in the valve hole?

Answer: Ford has been using band-mounted sensors for the last couple of years on many of its models, and the Chevrolet C4 Corvette (1987-1996) was the first vehicle to run band-mounted sensors. This idea has been copied by consumers to adapt valve-mounted sensors to wheels considered not TPMS compatible. Tire Rack does not recommend this since the sensors were not developed or tested to work in this position. They have also seen where sensors are taped, glued and/or epoxied to wheel barrels because the sensors will not fit in the valve hole correctly. This is also not an approved procedure.

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5. When should TPMS parts be replaced?

Answer: Every time the tire is removed, the sensor should have been dropped into the wheel before the tire is even dismounted. So every time the sensor’s position has been adjusted, the valve cap, nickel-plated valve core, valve nut and rubber grommet seal (and possibly the metal ring found at the base of the valve on many Siemens sensors) must be replaced with OE spec parts. Never reinstall a sensor without installing a new rubber grommet since this is the main cause of valve leaks.

The valve nut also should be replaced so it doesn’t endure the specified torque for a second time. Along with using a calibrated torque wrench on the valve nut, a valve core torque driver should be used when installing the nickel-plated valve core. As a precaution, warn your customers about using aftermarket metal valve caps. Many are made from steel or brass, which will corrode the aluminum valve over a short period of time.

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If you have other “top” or common questions regarding TPMS issues, please let us know. Source: Tire Review magazine


What’s New in TPMS?

By Scot A. Holloway, General Manger, Bartec USA, LLC

The increasingly hot topic of Tire Pressure Monitoring Systems (TPMS) is very controversial yet compelling. TPMS brings about confusion and aggravation, but more importantly, opportunity. Adding to the TPMS frenzy is loads of information. This article will discuss a couple of new issues within TPMS that you need to be aware of.

TPMS Sensor Commissioning
Recent developments in TPMS have some sensors showing up in the aftermarket in a storage mode. In order to conserve sensor battery life, TPMS sensors are sometimes shipped in “off mode,” “de-energized mode,” “accelerometer off” or “shipping mode.” In some instances like the “banded sensors” that Ford currently uses, simply putting the sensor under pressure will energize or turn the sensor on. Other sensors require a special Low Frequency (LF) command to change their mode. For the latter, a TPMS tool is required, one that has this special LF command.

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Diagnostic Point: Sensors that are not properly commissioned (or set-up), can be successfully programmed to the vehicle, only to have the owner drive away and have the TPMS warning light come on at a later time.

TPMS and DLC (OBD) Programming
The majority of the Asian vehicles have adopted a repair process that has made aftermarket repair of TPMS difficult. While there are some TPMS trigger tools that can in fact activate and decode the sensors found on Toyota, Honda and Nissan vehicles, in each of the cases another tool is required to perform sensor replacement — that tool is a scan tool.

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That’s right, each of these and many other import vehicles require a corporate scan tool to be connected to the Data Link Connector (DLC) to complete TPMS service. Every time a TPMS sensor is replaced or rotated, this scan tool must be connected to the DLC and the IDs keyed into the scan tool for programming to the vehicle.

What does that mean to the aftermarket? Well, a couple of things actually. First, TPMS is a little more complicated now that scan tools are involved; second, getting the right aftermarket TPMS tool is even more critical today than ever before. The aftermarket solution should be based on the same process by which the car or truck is programmed at the time of manufacture; a process derived from the OE method is the most accurate and efficient.

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TPMS Sensor Changes
With model year 2009 now upon us, keep your eyes open for some changes in sensor technology from the OEs. Ford is now using a “snap in” style TPMS sensor on some of their trucks and SUVs. Subaru has also changed its strategy as the company is now using both the “clamp in” and the “snap in” styles of sensors on certain models. Hyundai and Kia have added a new twist to the sensors they are using. Depending on the model car, the sensor’s status has to be changed from HIGH to LOW. This again requires a special LF command. Also new for Chrysler is a “snap in” variant to their current specification (on limited models).

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Unfortunately, the only thing consistent about TPMS is the change that seems to occur on a regular basis. To navigate through this challenge-filled opportunity you will need knowledge, training, technical support and superior tools. There is plenty of each and there are a few companies that offer the complete package.

Scot Holloway is the general manager of Bartec USA, LLC. Bartec USA and the Bartec Group of companies have long been experts in TPMS. With more than 80 TPMS installations worldwide, Bartec programs the TPMS of all varieties of makes and models. Currently, Bartec brings this level of expertise and understanding to the complete range of aftermarket TPMS tools. Visit www.bartecusa.com for more information on Bartec USA and Bartec Auto ID.

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