Auto Service Professional

FEB 2018

Magazine for the auto service professional

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Page 48 of 61

47 | ASP February 2018 Technical Relearning tips Once one or more TPMS sensors have been replaced, or a service such as tire/wheel rota- tion has been performed, a relearn procedure is likely required. ere are three basic types of relearns, depending on the make, model and year vehicle. ese include auto-relearn, stationary relearn and OBD II relearn. Auto Relearn applies to vehicles that are designed to learn sensor IDs without the need for a TPMS tool. Once the service has been performed, the vehicle simply needs to be driven for a predetermined amount of time in order for the system to reset. Depending on the vehicle, this may require as little as 5 minutes to as long as perhaps 20 minutes. However, to prevent wasting your time, it's advisable to first use a TPMS tool to trigger each sensor to verify that the sensors are functioning properly. It should be obvious that all tires must first be inflated to the placard's recommended pressure. A Stationary Relearn allows sensor IDs to be transferred to the vehicle ECU while in the shop. is typically requires a TPMS tool or an OBD II scan tool. An RF signal communicates with the ECU to inform the computer as to the location of each sensor wheel position. According to ATEQ, an example is the 2014 Ford Escape that features a standard ignition. Inflate all tires to the specification, turn the ignition off, press and release the brake pedal, cycle the ignition off to run three times, finishing with the engine in the run position. Next, press and release the brake pedal again, and then turn the ignition to the off position. Once again, cycle the ignition from off to run three times, finishing with the engine in the run position. At this point, the horn will sound twice (at least, it should). Use the tool to activate the left front sensor, at which point the horn should sound once. Repeat this process for the right front sensor, followed by the right rear sensor, followed by the left rear sensor. e sequence must be followed properly (LF, RF, RR, LR). e OBD II Relearn requires a TPMS tool to transfer the new sensor IDs directly to the vehicle's ECU. With the tool connected to the OBD II port, each sensor is scanned, following the prompts on the tool. e sensor IDs are then transferred to the ECU. Most Asian and European vehicles cur- rently require the OBD II relearn procedure. Referring to a 2011 Toyota Camry as an example, the procedure is as follows: 1. Inflate all tires to specification. 2. Read all sensor IDs using a TPMS/scan tool. 3. Connect the tool to the OBD port. 4. Reset the ECU using the tool. 5. Turn the ignition off, then to the on position. 6. Drive the vehicle at a speed of about 12 mph for about five minutes. Again, this is merely one example. Always follow the procedure provided by the auto maker's service manual or the instructions provided by the sensor and/or tool maker. GM keyless entry/TPMS problem Several GM models require the use of the keyless entry remote fob in order to perform a TPMS relearn. If the keyless entry system malfunctions, TPMS relearn may not be possible, as well as the dashboard information center showing TPMS faults. A cause of the issue may be related to allowing the vehicle's battery to drain. After Scan tools are available to allow activating, read- ing and relearning all known TPMS sensors. photo courtesy Autel

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