Auto Service Professional

FEB 2018

Magazine for the auto service professional

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34 | ASP February 2018 Technical Don't guess on torque! is basic service procedure is critical and cannot be over-emphasized. TPMS sensors can easily be damaged by improper tightening of stems, valve cores and/or caps. Seriously... this is no joke. Tightening "until it feels good" simply doesn't cut it. All sensor and sensor service kit makers provide torque specifications for core to stem, stem hex nut to wheel and replacement stem to sensor installations. When a specification calls for 40 in.-lbs., for example, you must use a quality, and properly calibrated, torque wrench that will release torque at 40 in.-lbs. If you don't want to use the correct tools and follow the correct torque specs, you shouldn't be servicing TPMS. Since TPMS sensors require relatively light torque specified in inch-pound value, you need torque-application tools that are specifically designed for these applications. You can certainly source these from a major tool supplier, but obtaining specialty TPMS torque tools is best done through your supplier of TPMS sensors, since they offer torque-application and specialty tools that are specifically designed for TPMS service. Even pre-set 4 in.-lbs. valve core torque wrenches are available. We can't over-emphasize the need to follow correct tightening values. e specified torque values must be followed to avoid valve, core and or sensor damage. TPMS sensor-related torque values are based on dry-thread torque. Do not apply lubricant to any threads, as this can reduce friction during tightening and can result in unintentional over-torquing. Tips from AirTech TPMS ere are no TPMS shortcuts. Following are steps to follow when troubleshooting TPMS. TPMS dashboard icon: solid or blinking? A solid icon indicates low or high tire pressure, or vehicle relearn required. A blinking light indicates a TPMS system error. is could indicate a wrong or dead sensor, or relearn required. Confirm if the vehicle is equipped with a spare wheel/tire assembly, and confirm if the spare has a sensor. 1. Inflate all tires to match the vehicle placard (including spare, if so equipped). Start the engine. If the warning light is still on, some vehicles require a short drive period. If tire pressure is not the issue but the light is still on, go to Step 2. 2. Scan all sensors with a TPMS tool. Verify that all sensors are functioning. If you can't obtain correct data from a sensor, the battery may be dead. Write down tire position and the last 5 digits of the sensor ID. Verify that there are no duplicates. If you know the sensor brand, try to modify the sensor ID. 3. Perform a valid relearn. Be sure to follow the specific relearn procedure for the vehicle. ere are many sources of abbreviated pro- cedures for a specific year/make/model, but some models may differ. e wrong relearn procedure simply won't work. Tips from ATEQ TPMS To avoid issues with your TPMS sensors, be sure to take the proper precautions to keep the sensors functioning properly. Some common practices include: – Avoid flat tire repair sprays. Some brands display "safe to use with TPMS sensors." An example of two fixed-value in.-lb. torque application tools, one labeled at 65 in.-lbs. and another at 40 in.-lbs. While 65 in.-lbs. is theoreti- cally equal to 5.41 ft.-lbs., DO NOT be tempted to try using a ft.-lb. torque wrench dialed "a bit below" the tool's lightest 10 ft.-lbs. mark in an effort to "guesstimate." You absolutely must use torque-limiting tools calibrated to the specific torque break-away limit to prevent damage. Photo courtesy Dill

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