Tire Pressure Sensor
The Tire Pressure Monitoring System (TPMS) uses 'active' tire pressure sensors which are mounted on each wheel, inside the tire cavity. The sensor is retained in position by the valve attachment to the wheel structure. The sensors transmit their RF signals at 433 MHz.
The sensors periodically measure the pressure and temperature of the air inside the tire plus the centripetal acceleration acting on the sensor. These measurements are transmitted periodically to the Radio Frequency (RF) receiver located behind the overhead console.
The tire pressure sensors are self contained units which have no electrical connections into or out of the sensor.
The care points detailed in the 'Tires' article of this chapter must be followed to avoid damage to the sensor. If the sensor is replaced, the nut, seal and washer must also be replaced and the sensor tightened to the correct torque value as given in the Service Information.
The RF transmission from the sensor contains a unique identification code in its transmission data, so that the TPMS can identify the tire on the vehicle. If the sensor is replaced on a 'running' wheel, the identification for that sensor may be programmed into the TPMSCM using a Jaguar Land Rover approved diagnostic system. That wheel will not be monitored till programmed or till the wheel is learned by the vehicle, which can take up to 15 minutes. The code is provided on a label with the complete wheel and tire assembly when new and is also printed on the casing of each sensor.
In order to conserve battery power, the tire sensor module uses different transmission rates when the wheel is stationary or moving. The wheel speed required to change between the stationary and moving transmission rates is very low to allow for the requirement for slow off road driving.