Tire pressure monitoring system
Tire pressure monitoring system (TPMS) is an active safety system, which measures the pressure in the tires. A sensor that measures the pressure inside the tire is attached to the tire valve itself. If the pressure falls below the set values, the sensor illuminates the yellow indicator light on the control panel. The indicator on the instrument panel for TPMS is the cross-section of the tire with the exclamation point in the middle.
There are two versions of the TPM sensor, indirect and direct. Indirect tire pressure information is read from the algorithm, wheel speed and vehicle speed. Tire size data is stored inside the control unit. With this type of sensor, the pressure is not measured but the speed of the rotation of the wheel, and the increase in the speed of the rotation of the wheel compared to the expected speed, the system recognizes the tire as empty and warns the driver of improper reduced pressure inside the tire.
With direct TPM sensors, unlike indirect sensors, the pressure in each tire is measured separately. Based on this, it can provide data on the pressure inside the tires and the temperature, which are algorithmically processed inside the control unit, and the observed irregularities are indicated on the control panel.
The sensors are numerically stored inside the control unit, and replacing the wheels on the vehicle without changing the position of the sensors in the control unit can lead to incorrect reading or indication which tire is losing pressure. If we use summer and winter sets of tires on the vehicle for each sensor, its position should be entered in the control unit so the system can work properly, and send accurate data.