Most of the time, technology is great. It’s become such an important part of our lives and has changed the way we work, communicate, and do daily tasks – heck, it just makes things easier for everyone…for the most part. However, as great as technology is, it can really grind your gears when it malfunctions or doesn’t work right, like when a customer’s TPMS light just won’t shut off.
While TPMS is an important safety function, a malfunctioning TPMS sensor can lead to time-consuming troubleshooting for your shop and technicians. If your customer’s tires are all filled up to recommended pressure yet the light remains on, what do you do? There could be other problems a shop has to address – like dead TPMS batteries, faulty sensors, a blocked signal to the module or a fault with the electronics.
Why the TPMS light comes on
TPMS sensors usually last five to 10 years, but this depends on the vehicle. When a sensor is nearing the end of its life, it may not always trigger a specific code on the TPMS tool, but instead send inconsistent signals to your customer’s vehicle. This can cause the TPMS light to either blink here and there or stay lit for a while, which could mean the sensor is failing.
While TPMS is an important safety function, a malfunctioning TPMS sensor can lead to time-consuming troubleshooting for your shop and technicians.
Sensor battery life depends on the mileage of the vehicle and the conditions it drives in. For example, stop-and-go traffic can affect the battery because sensors transmit more radio frequency transmissions when the vehicle is changing speeds, compared to vehicles traveling at a more constant speed.
How do you know which sensor is failing?
If one or more sensors are dying, it’s best to replace all four sensors at the same time. Once one sensor goes, the rest probably aren’t far behind, and replacing them all at once will save your customers from coming back to your shop.
To help you identify sensors that aren’t working, use the “test before touch” method, which includes a complete visual and electronic inspection of the vehicle’s TPMS. After pinpointing which sensor failed, determine the cause and explain what TPMS service you will perform for your customers.
Sensor failures aren’t always just technological – structural issues can also cause sensors to become faulty. If you didn’t find anything wrong with the tech itself, ask your customers if they recently hit a pothole or curb – this can cause a bent stem or improperly seated sensor, damaging it. If there is damage to the sensor, it’s best to just replace it.
If all sensors function fine and have no visible damage, the problem may be improper programming or the vehicle may need a relearn. For example, if the incorrect make, model, or year information was entered when the TPMS was originally programmed, the diagnostic tool might detect the sensor, but the vehicle’s ECU (Electronic Control Unit) won’t, causing the TPMS indicator to light up. Performing a relearn should resolve this issue.
TPMS sensors usually work off of a low-frequency signal. While it generally works fine, this signal can be prone to interference from anything transmitting in a similar frequency range. Cell phones or other sensors can cause this interference, so it’s best to keep TPMS sensors away from each other during a relearn and tell your technicians to keep their phones away from where they are servicing the sensor.
If all sensors function fine and have no visible damage, the problem may be improper programming or the vehicle may need a relearn.
If sensors are too close together, you may accidentally relearn a completely different sensor than the one that’s needed. Some vehicle manufacturers, like Ford, even recommend rolling down the windows during a relearn to avoid interference.
A TPMS module also may not be working correctly because of a lack of voltage supply, wiring issues or an internal electronics fault. When a TPMS module is struggling to receive signals from one or more sensors, check out the antenna wiring for issues and potential problems like shorts, open circuits, or high resistance in the wiring. If your inspection shows no issues with the antenna wiring but the TPMS module continues to show a “no sensor signal” code, the problem is likely with the module itself, which means the module may be faulty.
Make sure to let your customers know if the TPMS module needs to be replaced and verify the TPMS module’s voltage supply and ground connections before replacement. Low voltage can cause electronic modules to behave strangely.
In certain vehicles, the TPMS module shares signals with or receives information through the keyless entry system. With that being said, a wiring issue affecting the keyless entry could potentially cause issues with the TPMS. The TPMS module might be working fine, but it could be receiving incorrect data from the keyless entry system.
Whatever the issue with a stubborn TPMS light is, always consult the OEM service information specific to the vehicle you’re working on before repairing it – especially if you are having difficulty figuring out the problem. If you’re still having issues, check for any Technical Service Bulletins (TSBs) that might address that issue or provide an updated repair procedure. By following these tips, you can avoid grinding your gears and help your customers get back on the road with a working TPMS.
This story originally appeared on our sister site, Tire Review.
