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The system comprises a TPMS module, a RF antenna, 4 initiators and 4 or 5 tire pressure sensors, depending on the type of spare wheel fitted.
The TPMS module is located on the LH (left-hand) side of the trunk. The RF antenna is located beneath the rear of the vehicle. The front initiators are positioned at the front of the wheel arches, behind the fender splash shields. The rear initiators are positioned at the rear of the rear wheel arches, behind the fender splash shields.
The 4 initiators are hardwired to the TPMS module. The initiators transmit 125 KHz Low Frequency (LF) signals to the tire pressure sensors which respond by modifying the mode status within the RF transmission. The 315 or 433 MHz RF signals are detected by the RF antenna which is connected directly to the TPMS module. The received RF signals from the tire pressure sensors are passed to the TPMS module and contain identification, pressure, temperature and acceleration information for each wheel and tire.
The TPMS module communicates with the instrument cluster via the high speed CAN (controller area network) bus to provide the driver with appropriate warnings. The TPMS module also indicates status or failure of the TPMS or components. Tire Location and Identification The TPMS can identify the position of the wheels on the vehicle and assign a received tire pressure sensor identification to a specific position on the vehicle, for example FL (front left), FR (front right), RL (rear left) and RR (rear right). This feature is required because of the different pressure targets and threshold between the front and rear tires.
The wheel location is performed automatically by the TPMS module using an 'auto-location' function. This function is fully automatic and requires no input from the driver. The TPMS module automatically re-learns the position of the wheels on the vehicle if the tire pressure sensors are replaced or the wheel positions on the vehicle are changed.
The TPMS software can automatically detect, under all operating conditions, the following: •
one or more new tire pressure sensors have been fitted •
one or more tire pressure sensors have stopped transmitting •
reject identifications from tire pressure sensors which do not belong to the vehicle •
two 'running' wheels on the vehicle have changed positions. If a new tire pressure sensor is fitted on any 'running' wheel, the module can learn the new sensor identification automatically when the vehicle is driven for more than 15 minutes at a speed of more than 20 km/h (12.5 mph).
The tire learn and location process is ready to commence when the vehicle has been stationary or traveling at less than 12 mph (20 km/h) for 15 minutes. This is known as 'parking mode'. The learn/locate process requires the vehicle to be driven at speeds of more than 20 km/h (12.5 mph) for 15 minutes. If the vehicle speed reduces to below 20 km/h (12.5 mph), the learn process timer is suspended until the vehicle speed increases to more than 20 km/h (12.5 mph), after which time the |