TPMS: What are Dealers Doing? – UnderhoodService

TPMS: What are Dealers Doing?

Service shops aren’t the only ones concerned about TPMS these days. Auto dealers, also, are handling an increasing number of TPMS-equipped vehicles in their service bays.

While there’s strong competition for vehicle service, TPMS is forcing both auto and tire dealers to cope with a new side dish on their service menus. The common thread, however, is that TPMS is a relatively new science that no one yet has seemed to perfect.

Now, we’re not shedding a tear for the car dealers, just pointing out that they face some of the same TPMS struggles you do. Of course, they have better access to parts and information. At the same time, some of what car-dealer service managers and techs have learned can be helpful to service shops.

To illustrate, let’s consider Toyota, a company whose vehicles have been among the most sought after worldwide. In addition, the Japanese company said that it expects to sell 9.34 million vehicles worldwide next year, compared to the 9.2 million projected by General Motors. If that happens, Toyota will break GM’s 81-year-old claim as the world’s number-one automaker.

TPMS and Toyota
Toyota didn’t get to that position through passive interest in quality, components and the supply chain. It has taken a similar approach with TPMS.

“We are very much aware of the concerns of the new TPMSs,” said Jim Buner, service manager for Don Joseph Toyota in Kent, OH. “It starts when our new cars come right off the carrier trucks.” And, these days, Buner is dealing with several models newly equipped with TPMS. According to a Toyota technical service bulletin issued late last year, the company has direct-type TPMSs on 11 models: the 2004-2007 4Runner; 2005-2006 Tundra; 2005-2007 Sequoia; 2006-2007 Land Cruiser, Prius, RAV4, and Tacoma; and the 2007 Avalon, Camry, Solara and Scion tC.

In addition, Buner said that five other models use an indirect system: the 2001-2005 Sienna, the 2004-2007 Highlander, 2004-2005 Solara and RAV4 and the 2005 Scion tC.

Direct vs. Indirect
Buner says that a vehicle equipped with an indirect system poses some interesting problems in the service bays.

“In the early stages of TPMS, we just didn’t have enough information,” he said. “That was our biggest problem. Today, generally speaking, we don’t have too many problems with the indirect systems. They are fairly rugged. It would almost take a shot from a grassy knoll to disable one of those systems. It’s a ‘sensitivity’ issue more than anything else. Any time you take a tire off a vehicle, you’ve got to recalibrate whatever system you have in place.” He also noted that the caveat is the same with a direct system.

“You have to read as much information as you can because of the variety of systems that are available,” said Buner. “Once you think you’ve got it under control, then it’s time to worry.”

Toyota uses primarily one TPMS supplier – Denso. It recently signed a deal with EnTire Solutions to supply a direct system for the 2007 Toyota Sienna.

Recalibrating TPMS
Buner also stated that working with new vehicles is a fairly routine process. As soon as a Toyota service technician rolls a new car off the truck, the first part of the ‘ready’ process is putting the proper amount of air into the tires and recalibrating the sensors. “We don’t need any special equipment to handle the new systems,” said Buner. “The new cars are relatively easy. We check the inflation pressure, since they arrive slightly over inflated. We usually have to bleed them. Then, when they are filled with the correct pressure, we just press the reset button inside the glove compartment, and reset the system.”

Most of Toyota’s new vehicles come equipped with a direct system, and the tire pressure monitor ECU is located in the glove box. A low-tire-pressure warning light is located on the instrument panel next to the speedometer.

“Most of our technicians know how to use a scanning tool for recalibration,” said Buner. “For the entry-level techs, this is covered in classes that deal with electrical components. Our journeymen technicians already are accustomed to using the tool.”

Toyota stated that the “unique TD number must be manually entered into the ECU using a diagnostic tester whenever the tire pressure warning valve/sensor is replaced or after a tire and wheel are exchanged.”

Spares and Used Cars
Another factor to consider is recalibration of the spare tire. Toyota vehicles equipped with a TPMS sensor in the spares include: 2004-2007 4Runner; 2007 Avalon, Camry, Solara; 2006-2007 Land Cruiser, RAV4, Tacoma; and the 2005-2006 Tundra.

When a used vehicle comes in for any type of tire service, and it is determined to have a TPMS, the process is slightly different.

“If a tire pressure warning valve/sensor is removed from the wheel,” said Buner, “the grommet must be inspected and replaced if damaged.”

Speaking of damage, Buner added, “the biggest issue then becomes just avoiding breaking a stem or monitor. At this point, it’s critical to use extreme care in mounting and dismounting tires. The sensors are mounted inside the well of the rim. It’s important to be careful when using a tire-mounting machine. The sensor could be damaged in two ways: either by direct contact with the machinery or by the bead of the tire as it is forced over the wheel rim.

Pressures, Brands Critical
“The receiver is programmed at the factory to recognize which sensor is at each wheel location,” he continued. “If tires are rotated, or a sensor is replaced, the receiver must be reprogrammed, following recommended procedures. If the receiver is not reprogrammed, the system will continue to report the correct pressures, but will assign them to the wrong locations on the vehicle.”

TPMSs operate under the premise that irregular pressure in just one tire (including the spare) should trigger a low-indicator light.

However, Buner says that there is one Toyota vehicle that allows for different tire pressures, and that’s the Toyota Land Cruiser.

“The Land Cruiser is the only Toyota vehicle with a ‘Main/2nd’ switch,” Buner said. “This allows the owner to have two different sets of tires and wheels with two different sets of tire pressure warning valve/sensor ID numbers. For example, the second set might be used for snow tires. Therefore, we would register both the main and a second set of ID numbers using a scan tool.

“At this point, if our technicians are unfamiliar with this operation, we refer them to the technical service bulletin,” he said. “We receive many bulletins, and they are continuously updated. So, when in doubt, we refer to the most current ones applicable to the component or part.”

The last recommendation Buner makes could impact all dealers – auto and tire.

“It’s very important to use the same brand of tire on all four positions,” he insisted. “While you might have a 205/60R15 Michelin tire on the front of your vehicle, you can’t assume that a 205/60R15 Yokohama, for example, would function the same from a TPMS standpoint. The reality is that the height of the tire – from brand to brand – could be different. Also, it’s extremely important to have the same aspect ratio on the front and the rear.”

There is another reason varied aspect ratios are a concern: “We had a customer who brought in an all-wheel-drive Previa with 205/60s on the front and 205/65s on the rear. We made all the correct calibrations to the system, and he went on his way. After about 50 miles of driving, he came back and said he smelled burning. What had happened was, because of the difference in the aspect ratio between the front and the rear, his system ‘read’ that his tires were slipping, and it engaged the all-wheel-drive at 65 mph on dry pavement.”

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