Auto Service Professional

FEB 2018

Magazine for the auto service professional

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35 | ASP February 2018 Technical However, the glue can stick to the sensor and prevent it from working properly. – Avoid over-torquing the TPMS valve stem nut. is can easily break the sensor stem. – When cleaning the TPMS sensor port during inspection, don't allow any sharp objects to puncture the diaphragm, as this can damage the sensor. – For clamp-in sensors, always use new rubber seals between the sensor and the wheel to prevent sensor damage or leaks. For example, never re-use grommets or O-rings for clamp-in sensors. ey develop set dimen- sions that eventually become permanent to the TPMS sensor. – When replacing a snap-in sensor, always replace the valve. If you cannot read tire pressure informa- tion from the vehicle using your TPMS tool, first determine which TPMS light is on... a malfunction indicator lamp MIL or telltale light. e MIL will blink when the ignition is turned on, indicating a failure of operating the TPMS, such as a dead sensor. e telltale light will remain solid to warn the driver when their tire pressure is below 25% of the placard pressure. Next, determine if the vehicle has a direct or indirect TPMS. Direct TPMS uses TPMS sensors inside the wheels to report pres- sure data to the vehicle's ECU in real time. Direct systems include domestic, Asian and European vehicles. An indirect system uses an ABS to monitor the speed of the wheel and communicate with the ECU. Indirect systems include some Asian and European vehicles. ere are ways to determine whether the vehicle is equipped with a direct or indirect TPMS. – Use your TPMS tool to look up the make, model and year of the vehicle to determine the relearn procedure. It should list whether your system is a direct TPMS (auto, station- ary or OBD II relearn procedure) or indirect TPMS. – Refer to the Tire Industry Association (TIA) or your service information provider relearn chart to determine the type of system. – Demount the tire to verify which system you are working with. If there is no TPMS sensor in the wheel, and the vehicle is 2008-present year, the vehicle has an indirect TPMS. If the vehicle is older than 2008, indi- rect TPMS were available in many vehicles, so be sure to visually inspect the valve. A TPMS sensor valve has a visible "shoulder" shape on the valve, where a valve with no TPMS sensor attached does not have the same shape and is easier to physically move back and forth. If you are working with a direct TPMS and your TPMS tool still does not display the vehicle make, model and year, you may want to update your tool to the latest software version. Tips from Autel Intelligent Technology Corp. One of the most common TPMS tool feature purposes that customers don't understand is the difference between a sensor relearn and a sensor program procedure. ey think programming and relearn are the same thing, but they are two different procedures that offer different benefits. Users don't understand the fundamental differences between the features and why one is more useful than the other. e ability for a sensor to provide both By taking advantage of a torque-limiting tool that is preset to one specific in.-lb. value, there is no need to adjust the tool. Apply rotation until the application torque releases. Photo courtesy Dill

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