Raise your hand and repeat after me, “I will always ask my customer if their vehicle’s tire pressure monitoring system (TPMS) warning light is on and I will always double check and document this before ever driving their vehicle into the shop.”
You might be asking yourself, “Why is this necessary? I know what I’m doing when it comes to TPMS issues.”
Great question, and it comes down to a saying you’ve probably heard repeatedly your whole life, “Ignorance of the law is no excuse.”
There is one area of TPMS service that must not be overlooked. It is the “make inoperative” words in the Federal Motor Vehicle Safety Act.
Must you repair a faulty system before the vehicle can be returned to the customer?
According to the law, “A manufacturer, distributor, dealer, or motor vehicle repair business may not knowingly make inoperative any part of a device or element of design installed on or in a motor vehicle or motor vehicle equipment in compliance with an applicable motor vehicle safety standard prescribed under this chapter....”
What, exactly, does that mean? When asked, a surprising number of dealers think that the only illegal action that they or their technicians can take is to purposely disable the TPMS system. Many also believe that they may not legally release a car back to the customer if the warning light is on.
In an effort to clarify this, the Tire Industry Association (TIA) sent a letter to the National Highway Traffic Safety Administration (NHTSA) asking for clarification on several key points regarding four different TPMS scenarios that service professionals regularly face. It is critical for every dealer/installer to know how NHTSA responded.
Each scenario includes how the “make inoperative” provision of the Motor Vehicle Safety Act (49 USC 30122(b)) applies to each situation.Scenario 1: Can a retailer replace an inoperative TPMS valve stem sensor with a standard rubber snap-in valve stem and still comply with the “make inoperative” provision?
NHTSA’s response was that as long as the TPMS part was inoperative before the customer brought the vehicle to the repair business, “a motor vehicle repair business would not be violating 49 USC 30122(b) by removing an inoperative or damaged TPMS sensor and replacing it with a standard snap-in rubber valve stem.”
However, a motor vehicle repair business that goes on to make any other element of the TPMS system inoperative, for example, by disabling the malfunction indicator lamp, would violate the “make inoperative” provision. Hence the importance of documenting an inoperable TPMS prior to any work being performed on the vehicle.
Scenario 2: If a customer purchased aftermarket performance tires and wheels and the customer refused to purchase new TPMS sensors or pay for the labor to transfer the original sensors to the aftermarket wheels, what would happen?
NHTSA responded that if the TPMS is functioning at the time of the aftermarket tire and wheel purchase, “a service provider would violate the ‘make inoperative’ prohibition of 49 USC 30122(b) by installing new tires and wheels that do not have a functioning TPMS system. To avoid a “make inoperative” violation, the service provider “would need to decline to install the new tires and rims, use the TPMS sensors from the original wheels (if they are compatible), or convince the motorist to purchase new TPMS sensors and ensure that the sensors are properly integrated with the vehicle’s TPMS system.”Scenario 3: Is a service provider violating the “make inoperative” provision if they inadvertently break a non-defective sensor and cannot locate an immediate replacement but would allow the vehicle to return to service because arrangements were made to obtain and install the replacement part at a future date?
NHTSA’s response was, “As a general matter, a violation of the ‘make inoperative’ prohibition does not occur until a repair business allows or intends a vehicle to be returned to use... this would be true regardless of whether arrangements have been made for future repair.”
“While there will be some debate over the circumstances related to inadvertent damage, there are no questions regarding the release of the vehicle,” says Kevin Rohlwing, senior vice president of training for TIA.
“If the actions of the service provider made a functioning TPMS inoperable, then it cannot be returned to service until the problem is solved.”
Scenario 4: What happens if a vehicle is released to the consumer without an illuminated malfunction indicator light (MIL) and then it illuminates after the vehicle has been driven?
According to NHTSA, “The mere illumination of the malfunction indicator lamp after the vehicle has been released by a motor vehicle repair business to the driver would not itself be a violation of the ‘make inoperative’ provision.”“Based on NHTSA’s response, we are advising tire retailers to document the status of the TPMS before and after any tire or wheel service,” concluded Rohlwing.
“If the electronic TPMS relearn or diagnostic tool includes the functionality to produce a print-out on the status of the system, we recommend that retailers give a copy to the consumer and retain a copy for their own records following service.”
Of course, offering to repair the malfunction is the best solution. ■
A Quick Review of Sensors
Estimates put the total number of TPMS systems currently found in the U.S. at over 100 million. Many of the original TPMS sensors are reaching the end of their projected service life. The batteries, which are intended to last up to 10 years, are dying. The batteries are not replaceable.
When it comes to selecting a replacement sensor, you have three basic choices:
1. Direct replacement, or “part for part” replacement sensors, can be obtained from original equipment as well as aftermarket providers, and typically do not require any programming or configuring with a TPMS tool.
2. Multi-protocol sensors, as the name suggests, come “pre-loaded” with many sensor protocols in a single sensor body. Again, no configuring is required, but a TPMS tool is needed to do the “re-learn.”
3. Programmable sensors typically represent fewer SKUs, but are able to cover a greater range of vehicles. The sensors are blank or in need of configuration before use.
There are two basic types of sensors: One-piece and two-piece.
One piece: A one-piece sensor has the housing and valve molded together. The valve is not removable. The items that should be serviced on this style of sensor include the valve core, hex nut, grommet, cap and washer. If the valve is broken or corrosion has occurred, this sensor is not serviceable and the entire sensor will need to be replaced.
Two piece: A two-piece sensor has a removable valve stem that can be separated from the sensor housing. The serviceable items on this style of sensor are a replacement valve, valve core, hex nut, grommet and cap. With this type we also have two different valve configurations.
OE manufacturers recommend replacing the two-piece, snap-in rubber valve whenever the sensor is removed from the wheel. The rubber snap-in valve is attached to the sensor module by a hex nut (or Torx screw).
When two-piece, clamp-in sensors are removed from a wheel, the sensor should be fitted with a new rubber grommet, aluminum retaining nut, special nickel-plated valve core and valve cap.
It is important that all components be torqued to appropriate values to prevent air leaks and valve damage. Attempting to reuse the original rubber grommet, valve core and retaining nut may result in an air leak.
There are three types of sensor relearns: stationary, OBD and auto learn.
Stationary relearn sensors need an activation tool with the car in “relearn” mode. New IDs can be programmed without driving the vehicle.
OBD relearn requires an activation tool in conjunction with an OBD scan tool to program new sensor IDs into the vehicle. New IDs can be programmed without driving the vehicle.
With the auto learn sensor, the vehicle can learn a single new ID and in some cases multiple new IDs without the use of a tool. The vehicle must be driven a prescribed time in order to turn off the light.
You do not need to memorize the various relearn protocols. Each carmaker provides the necessary information. And there is a convenient relearn chart from TIA.
The TPMS chart is divided into domestic and import vehicle sections and includes relearn requirements, relearn summaries, OEM sensor part numbers, and replacement sensor and seal kit part numbers for popular manufacturers and suppliers.
The chart lists the torque specs for the sensor nut, Torx bolt, worm gear and vehicle wheel fasteners.
The TPMS Relearn Chart includes troubleshooting tips to help technicians when the relearn is not working, revised relearn summaries so that they are more easily understood, pictures and part numbers for common multi-app, programmable sensors on the market and a valve reference page with pictures and part numbers of the various type of TPMS valves. It can be ordered at www.tireindustry.org.
Bob Weber is president of Virginia-based Write Stuff. He is an award-winning freelance automotive and technical writer and photographer with more than two decades of journalism experience. He is a National Institute for Automotive Service Excellence (ASE) certified Master Automobile Technician, and has worked on automobiles, trucks and small engines. He is a member of the Society of Automotive Engineers (SAE) and numerous other automotive trade associations. He has worked as an auto service technician, a shop manager and a regional manager for an automotive service franchise operation.