Questions You Should Know about TPMS Sensor Tool

There are roughly 103 million vehicles on the road today equipped with a tire pressure monitoring system. Offering the servicing of these systems to your customers will not only result in a new revenue stream but also will improve customer retention as you educate them about this vital vehicle safety system.

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What is TPMS and when did automakers start adding the system to their vehicles?

TPMS stands for &#;tire pressure monitoring systems&#; and while a few automakers such as Porsche and Cadillac were early voluntary adopters, the federal government, in an effort to improve vehicle safety, made TPMS a mandatory system on all cars and light weight trucks on the road beginning September 1, . Under the Transportation Recall Enhancement, Accountability, and Documentation (TREAD) act, automakers needed to include a system on its vehicles that would detect and alert drivers to low air pressure&#;25 percent of the OE-specified&#;on one or more of the tires.

Is TPMS an effective safety feature?

A resounding &#;yes.&#; Plus, the systems are money savers, too. According to the National Highway Traffic Safety Administration, TPMS saves 660 lives per year, prevents 33,000 injuries and saves $511 million worth of gas. 

What is the difference between a steady TPMS light and one that flashes?

A steady TPMS light indicates that one or more of the tires is below the recommended air pressure value. When the air pressure is adjusted to the placard value posted on the driver&#;s door jamb, the light should no longer display. 

A flashing TPMS light&#;flashes for about 30 to 90 seconds and then lights solid&#;upon starting the vehicle that indicates that there is something wrong with the vehicle&#;s tire pressure monitoring system. The components of a direct systems include the module, sensors and one or more antennas. 

How does TPMS work?

There are two types of TPMS: direct and indirect systems. 

The direct system features a pressure sensor/transmitter on each tire that periodically measures the air pressure on the wheel and transmits that information to the vehicle&#;s TPMS module. If the pressure is off by 25 percent, a TPMS light will display. Vehicles with high-line systems will display the location of the tire with low pressure. 

The indirect system does not use sensors but rather uses the wheel speed sensor of the anti-lock braking system (ABS) to compare the relative speed of one tire to another. If a tire&#;s pressure is low, it will roll at a different speed than the other tires. The vehicle&#;s ECU will detect this discrepancy and display a TPMS malfunction indicator light (MIL) on the dash. 

What is involved in servicing a direct TPMS?

The most vulnerable components of the direct TPMS are the sensors. Visually inspect each wheel sensor for damage. The sensors are ripe for corrosion as they are exposed to salt, water, ferrous brake dust, extreme temperatures and significant vibrations. While inspecting for physical damage, which is the main culprit of sensor failure, use a TPMS tool to test the battery strength. Sensor batteries last on an average of between five and seven years. If the sensor needs to be replaced, remove the tire from the rim. Remove damaged or non-functioning TPMS sensors. Next, install the programmed replacement sensor. 

If the replacement sensor has a different ID from the previous sensor installed on the tire, the new ID must be registered (Relearned) to the vehicle module; The system uses the IDs to recognize the sensor and its associated tire&#;s pressure.

What are the types of TPMS sensors?

There are three aftermarket sensor types: direct replacement, multi-protocol, and programmable.  Direct replacement sensors are purchased pre-programmed with the protocol of the original OE sensor&#; a direct, one -to-one fitment replacement. Multi-protocol sensors are also pre-programmed but with multiple vehicle protocols. Programmable sensors are purchased blank to be programmed with a TPMS tool to replace the OE sensor.

What are the three Relearn methods and what is involved in each?

A good TPMS tool will display the relearn procedure for the specific vehicle entered by make, model and model year in tool. The vehicle manufacturer determines the relearn for each vehicle. There are three relearn types, stationary, dynamic, OBDII, though some vehicles require performing one method in conjunction with another. 

The stationary method involves putting the vehicle in &#;relearn&#; mode and activating the sensors. The dynamic or auto relearn involved driving the vehicle for specific length of time and the OBDII relearn method involves connecting the TPMS tool to the OBDII port.

What would I need to invest in to offer TPMS as a service?

foxwell supply professional and honest service.

To offer TPMS service, a shop needs a dedicated TPMS tool, TPMS sensors and TPMS rebuild kits (valve caps, screws, valve cores). However, there is a world of difference between simply offering the service and positioning your shop to make TPMS servicing an efficient and lucrative new revenue stream. 

Autel, a leading developer of automotive diagnostic scan tools, has been in the TPMS industry for close to a decade and offers a comprehensive approach to TPMS service. Autel offers advanced, yet easy-to-use TPMS tools and the aftermarket industry-leader,  the 1-Sensor&#;a dual frequency, universal programmable sensor that boasts the ability to be programmed to replace 99 percent of the sensors on road today. No need to stock hundreds of sensors or wait on the parts shop to deliver.

The 1-Sensor is available in metal and rubber press-in secure/release valves and a screw-in adjustable valve stem. No other company in the industry develops both sensors and tools, making Autel&#;s sensor software coverage quicker-to-market and more accurate than other aftermarket programmable sensors. 

For more information call 855.288., [ protected], or visit autel.com, maxitpms.com, maxisysadas.com

What is one of the leading causes of sensor failure?
Corrosion, sensors or sensor stems can be damaged by corrosion from road salts, moisture, missing valve caps or galvanic corrosion. The use of dissimilar metals or use of non-TPMS components can result in galvanic corrosion, which may affect the sensor&#;s ability to read or transmit data.

TPMS Sensors being programmed at the factory. Courtesy of Bartec USA

How many TPMS Sensors are on the road?
There are more than 200 million TPMS sensors now on the road. More than 35% of the sensors are now at least three years old. It has been estimated that more than 9 million sensors will need to be replaced in the next two years.

What percentage of the sensors and systems can relearn on their own?
Less than 40% of the vehicles can re-set themselves. Many &#;Auto Learns&#; can only do one new TPMS Sensor. For the other 60 percent, these vehicles require an activation or activation/scan combination tool.

What are the common standards for TPMS systems?
There is no common standard for the TPMS sensors with variations including frequencies, modulations, data structure, communications protocols, mechanical fitment and many other factors. While U.S. law mandates that the TPMS must warn the driver when a tire is under-inflated by 25%, it did not specify any standards for the equipment.

To reprogram and relearn some sensors it might require a tool that communicates with the vehicle through the OBDII port. Courtesy of Bartec USA

What information is transmitted by the sensors?
The sensors transmit data such as their unique sensor ID, temperature and pressure, battery life and other diagnostic information.

How long do the batteries in the sensors last?
It depends on a variety of factors including the sample rate, drive cycle of the customer and even the environment. If a sensor transmits the pressure every 10 seconds,  it will not last as long as a sensor that transmits the pressure every 15 seconds. Some sensors may last as long as ten years while some may last only three to five years.

How do I know if a vehicle is equipped with direct TPMS?
All vehicles manufactured after will have TPMS. If a Vehicle is equipped with TPMS, a lighted universal symbol on the dash will be illuminated when the iginition is turned to the &#;On&#; position. If this does not work, try use the learn and test procedure with a TPMS tool.

Remember, visually, a snap-in TPMS sensor looks very similar to a standard tubeless tire valve (TTV). Always check the owner&#;s manual or turn the ignition on and look for the universal TPMS symbol to determine if the vehicle has TPMS.

What does it mean if the TPMS warning lamp illuminates?

When the TPMS warning lamp on the instrument panel illuminates while driving, it means that the system has detected at least one tire with a pressure below the accepted minimum psi for the vehicle.
The tires should be inspected and the tire pressure checked as soon as possible. The lamp will extinguish after the tires are properly inflated.

What does it mean if the warning lamp goes on and off?
On cold mornings, the warning lamp may illuminate for a short period of time and then extinguish. This type of warning lamp response is likely caused by marginally low tire pressure that dips below the warning threshold over night, but rises to an acceptable level as the tires heat up through vehicle operation or an increase in ambient temperature. The tires should be inspected and the tire pressure should be checked. The lamp should not illuminate when the tires are properly inflated.

What does it mean if the  lamp flashes on and off and then remains illuminated?
All TPMS installed on model year vehicles and beyond are required to detect and warn the driver when the system is not functioning properly (malfunction indicator). For some TPMS, a system malfunction is indicated by a flashing of the low tire pressure warning lamp for a period 60 to 90 seconds with the warning lamp remaining illuminated after the flash sequence. The flashing sequence followed by continuous illumination of the warning lamp will repeat at each subsequent vehicle start-up until the malfunction is corrected. A vehicle dealer should be contacted for a system inspection.

Why does tire pressure change?
Many factors affect tire pressure including ambient temperature changes and tire damage, such as punctures. Tire pressure drops about 1 psi for every 10 degrees F drop in ambient temperature. Additionally, tires lose as much as 1.5 psi per month as air escapes the tire and rim naturally.

What should be replaced when a sensor is removed from the rim?
The grommets around the base and nut of the sensor must be replaced every time the sensor is removed from the wheel. The material in seals has a &#;memory&#; of where it was placed and the amount of clamping force. When the old seal is taken of the rim, it is deformed and will not properly reseal if it retightened.

Service packs provide the sealing components for each applicable sensor (clamp-in or snap-in) and can be replaced just as valve stems are today. Each time a clamp-in sensor is removed from the rim hole, the grommet, nut, nickel-plated core, cap and any other components supplied in the service pack should be replaced. Snap-in sensors should also have their rubber insert replaced each time the sensor is removed from the rim hole. The inserts should be replaced just as a standard valve stem is today.

There is a new valve core in the service pack. Do I really need to replace it?
Every time a sensor is serviced, the valve core should be replaced with the valve in the service kit. The valve core is Nickel-plated and prevents galvanic corrosion and insure integrity of the primary seal. To prevent galvanic corrosion, never use a brass valve core with an aluminum TPMS sensor. Instead, always use a nickel-plated valve core with an aluminum TPMS sensor.

What is the torque value required for the nut?
Typical torque values for the base nuts on a TPMS valve stem range from as low as 35 in.-lbs. of torque to as much as 80 in.-lbs. of torque. That&#;s quite a range. This does not mean that any torque value within this range is acceptable. It means that the torque specifications for the base nut on one car might require 44 in.-lbs., another might require 62 in.-lbs. EXACTLY, another might specify 71 in.-lbs. EXACTLY, and so on. Don&#;t guess. Look up the torque specifications for the vehicle you are servicing to make sure you use the correct torque.

Why should the nut be replaced every time a sensor is serviced?
The nut is made of a softer metal than the stem, so it will be damaged, and not the sensor, if it is overtightened. The material of choice is typically aluminum. If the nut is over tightened, it will develop hairline cracks.

Will sealants damage a TPMS sensor?
Some tire manufacturers and TPMS sensor manufacturers do not support the use of tire sealants. The use of any liquid or tire sealant injected into tires equipped with tire pressure sensors is not recommended and may cause the tire pressure sensors to malfunction. One manufacturer of sealants states: &#;&#;sealant may come in contact with the sensor in a way that renders the sensor temporarily inoperable until it is properly cleaned, inspected and re-installed by a tire care professional.&#; But, it also states that the sealant is water based and will clean up with no adverse effects.

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