The first step in any TPMS diagnostic strategy is to figure out whether or not your customer’s vehicle actually has a TPMS problem. Why? Simply put, there are a number of factors that can cause a TPMS warning light to illuminate or flash — and some are hard to uncover.
The light should illuminate when a tire is low (25% below the OEM-mandated inflation pressure) and should eventually go out after the low tire has been inflated to its proper pressure. The winter season always leaves a few heads shaking when drivers see the TPMS light illuminate on cold mornings only to go out once the tire is warmed up during normal operation.
Of course, extreme cold is the exception. In normal operation, if the light remains on after checking/inflating the tires, or if it flashes and remains illuminated, it may signal a TPMS problem that will require further diagnosis.
TPMS problems can include any of the following:
- A TPMS sensor has stopped functioning because its battery has died.
- A TPMS sensor is working intermittently due to a weak or failing battery.
- A TPMS module is not receiving signals from one or more sensors because of an antenna or wiring fault.
- A TPMS module is not functioning properly or has failed because of a voltage supply, wiring or internal electronics fault.
- The relearn procedure not being done correctly after a tire rotation or other service.
- The vehicle’s owner not understanding how the TPMS works.
In preparation for the upcoming colder months when we will start to see a higher frequency of TPMS warning lights, be sure your TPMS scan tool is up to date so you can be ready to help your customers determine if there is a system fault or just simply low tire pressure.
Look for more TPMS diagnostic strategy in the next issue of TechShop.