TPMS in the modern age
Since the TPMS mandate came into effect in the United States in 2007, independent repairers have spent time acquiring the knowledge and skills to meet the new TPMS service requirements to find that the technology and implementation continue to evolve over time. This change in methodology has left many repairers struggling to follow the new repair procedures.
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Traditionally, when servicing many Chrysler vehicles, technicians would benefit from the simplicity of its automatic relearn procedure. After successfully programming and installing replacement sensors, it takes a short drive for the vehicle to locate all four wheels and display wheel pressures and locations on the Driver Information Center. How does he do this?
RF TPMS antennas are located near each wheel and tire assembly. There are 2 antennas in the front and one in the back. The ignition switch module acts as the fourth antenna – representing the four wheels. During a test drive at sustained speeds above 15 mph, the sensor accelerometers will activate the sensors and transmit the sensor ID and wheel location information to the controller. The level of equipment and components required for this system to function properly are complex and expensive to integrate, but it simplifies the relearn process for technicians.
Since 2018, Fiat Chrysler Automobiles (FCA), along with other manufacturers, has been developing technologies to protect their vehicle networks against unauthorized access, including potential cyber attacks. FCA recently implemented a Secure Gateway module which was introduced on a selection of its 2018 and newer vehicles.
For vehicles equipped with a Secure Gateway (SGM) module, access to certain diagnostic functions requires registration and authentication through an approved device. This is true for all aftermarket analysis tools that participate in the AutoAuth program. In some cases, special access may be required for TPMS service procedures that include changing the sensor ID configuration.
The first attempts to bypass the SGM module required the use of a dedicated drop cable. This involved disassembling the interior sections of the vehicle to access the physical SGM module and plug the cable directly into the SGM controller. Removing components such as the infotainment screen or interior floor trim to access it has proven to be time consuming and impractical for simple maintenance procedures, such as relearning the TPMS.
Due to the addition of the SGM module, when attempting to machine learn an FCA vehicle where a new sensor has been added, technicians can sometimes have difficulty relearning the new sensor IDs on the control module. TPMS command. Some TPMS-equipped diagnostic tablets are equipped with access to AutoAuth software, a third-party subscription-based software service that will provide access to all vehicle systems including TPMS through the safety feature.
It is important to note that there is always access to output data including code scan, live data, and freeze frame data without special permission. The limitation appears when a technician attempts bidirectional functions. Without access, we cannot operate vehicle systems, perform component activation or service bay tests on the vehicle.
Where does this fit in the TPMS? When adding or changing any of the vehicle’s TPMS sensor IDs, they must be taught to the vehicle. This is a bidirectional function which can be blocked by the SGM. A simple tire rotation or tire replacement is not a problem as the IDs stay the same, and all that changes is the location of the wheels.
Autel technical support is constantly responding to calls from technicians who cannot successfully service vehicles equipped with SGMs with universal programmable TPMS sensors. Armed with the knowledge of these systems, a subscription to AutoAuth and a capable TPMS and service tool eliminates the complications of maintaining these systems.
What if we try to get away with a more modest TPMS tool that isn’t capable of using an AutoAuth subscription?
The most important consideration when servicing a Chrysler vehicle equipped with SGM is that no matter how many sensors are replaced, the sensor IDs should remain consistent with the factory equipment. To do this, we need to consider the sensor programming method we use before installing the sensor. Most TPMS tools will offer an “auto-create” programming method that will assign the new sensor a random, but compatible ID, and the correct communication protocol for the vehicle. This method will prove ineffective because a new identifier will not be accepted by the system. Instead, the recommendation is to stick with a cloning method.
These methods are available on most portable TPMS tools – on Autel’s TS508 tool in particular, this can be accomplished in several ways. We can use the “Copy By OBD” programming method. A sensor is duplicated based on the information stored in the control module.
The tool will communicate with the vehicle through the diagnostic port and access the controller’s existing credentials. This will allow the replacement sensor to be programmed using the credentials of the current sensor. Cloning or “copy-by-activation,” as shown on the TS508, will allow technicians to activate the old sensor, if the sensor is still functioning, and extract the old credentials. We can then create a new sensor with the same credentials and characteristics.
Or, we can choose a “manual input” programming method if the sensor battery is discharged or if it cannot activate. A manual entry programming method will allow the technician to manually type the ID stamped on the original sensor into the TPMS tool and create a sensor with the same ID. These programming methods will maintain consistent credentials between new and old sensors and eliminate the need to “learn” new sensor IDs from the vehicle.
Although the sensors used in systems equipped with SGM are fairly new and will not require immediate replacement, there are certain circumstances in which we would be required to repair the TPMS system on these vehicles.
Winter tires, for example, are mandatory in some Canadian provinces, including Quebec and British Columbia. Many motorists may choose to store and maintain a set of pre-defined wheels and tires with TPMS sensors preinstalled. Creating replicas of existing sensor IDs is the easiest way to eliminate the complications of swapping sets.
There may also be scenarios where a vehicle can be damaged due to road hazards or collisions. It’s never too early for tire installers to familiarize themselves with these new technologies and service requirements. It is important to gain a thorough understanding of these new systems now so that we are fully prepared to meet the needs of our customers as the demand for service increases among these models.
The primary goal of the aftermarket automotive tool industry is to stay ahead of the technology and deliver the next generation of solutions. Additional service capacity will always translate into new revenue streams for repairers. Manufacturers of innovative industrial tools will continue to adapt to these changes, ensuring our customers current and future success.