Originally Posted By: yonyon
It isa important to differentiate between the TPMS light being on and the light first flashing, then staying on. Whereas coming on and staying on should indicate low tire pressure; an indicator flashing and then staying on would indicate a system fault such as from a damaged sensor.
That said, TrailBlazer is a GM product. The computer needs to be told which sensor is at which wheel position. After rotating the tires and setting the pressures it will see two tires as being underinflated and two tires overinflated unless the system is retrained. Retraining can be done in two minutes. Stop by the place that put the tire on. Don't let them charge you for doing it.
Most shops charge a flat rate for calibration. That said, if your car had sensors and they never told you about calibration or did it, then you shouldnt have to pay.