Technical
TPMS diagnosis and service tips Advice from parts & equipment manufacturers As you know, tire pressure monitoring systems (TPMS) have been mandatory on new vehicles since 2008. Servicing these systems involves sensor replacement, proper programming and relearning. However, there are a number of common misconceptions and misunderstandings of how some of these systems operate, especially regarding diagnosis, inspection, handling and vehicle-specific procedures. In this article, we’ll share advice and tips regarding TPMS service.
By Mike Mavrigian
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ikely the leading cause of system failures lies with the condition of the sensor batteries. Sensor batteries are expected to last around six to 10 years, with newer sensors lasting longer due to battery improvements. The rule of thumb is that once a single sensor goes bad, it’s likely that the others are soon to fail as well. Make this an educational opportunity for the customer. Explain that sensor batteries have a finite lifespan. Let them know that it’s likely time to replace the other sensors. Otherwise they may need to return to the shop once another battery dies. Always give them the option of changing them now or letting them know that they will likely need sensors in the not-too-distant future. Replacing all the sensors at the same time avoids having the customer face another tire/ wheel disassembly, remount and balance in the near future simply due to dying or dead sensor batteries. In addition to the ability to perform
programming and relearning, TPMS scan tools are available that allow the technician to read individual tire pressure and individual sensor battery condition on-screen, alerting you of low/bad battery state.
Not the batteries? Other issues can arise that have nothing to do with sensor battery life. One or more sensors may have trouble getting the signal through to the module, which could be a damaged antenna or a wiring issue, or a bad module. EMI (electromagnetic interference) also can cause issues that disrupt the TPMS signals, such as another wiring harness running too close or touching the TPMS harness, similar to an engine misfire when (depending on the application) two spark plug wires run against each other. Depending on the design of the vehicle’s electrical system, keyless entry systems also can present problems if TPMS signals run through the keyless entry system, where a keyless system glitch can in turn prevent the correct TPMS signals from communicating properly.
32 | ASP February 2018
