Tire pressure monitoring system (TPMS) (Freelander 2)

Pos.	spare part no	Name
1	-	Battery junction box
2	-	Dashboard
3	-	RF receiver
4	-	Activator
5	-	Central electrical box (CJB)
6	-	Tire pressure sensor

TPMS is a system that helps the driver keep the tire pressure at the optimum level. TPMS is standard on North American vehicles (NAS), and as an option for other markets. The TPMS system provides the following benefits:

• Reduced fuel consumption.
• Maintaining good performance and dynamic characteristics.
• Reducing the risk of sudden tire flattening that can occur due to tire under-inflation.
• Compliance with applicable legal requirements.

WARNING: TPMS is not a substitute for regular tire health and tire pressure checks, it should be considered as an additional tool to keep tires in good condition.

The air pressure monitoring system measures the air pressure in each tire (if necessary, including spare tire) and warns the driver if the air pressure in at least one tire is out of range.

NOTE: In case «depressurization» tires usually experience a very rapid pressure drop. The system is not designed to notify the driver about «depressurization» tires, because it is impossible to do in such a short time. The purpose of the TPMS system is to help the driver maintain the correct air pressure in the tires, which reduces the risk of «depressurization» tires.

The TPMS control software is located in the CJB. The software detects the following states:

• If the air pressure in the tire drops below the minimum value, the tire is under-inflated.
• The position of the tire on the vehicle.

The system includes a high frequency receiver, 4 activators and 4 tire pressure sensors (5 if the sensor is installed on the steering wheel).

4 activators are rigidly connected to the CJB. The initiators send low-frequency signals of 125 kHz to the tire pressure sensors, which, taking into account these signals, change the status of the mode during high-frequency transmission. The 315 or 433 MHz radio frequency signals are received by a high frequency receiver located at the rear of the vehicle, under the roof lining. The RF receiver is connected to the CJB via the LAN interconnect bus (LIN). The high frequency signals received from the tire pressure sensors are transmitted to the CJB via the LIN bus, they contain the identification data, pressure, temperature and acceleration information of each wheel and tire.

The TPMS software communicates with the instrument cluster via the medium speed CAN bus to provide the driver with appropriate warnings. The TPMS software also indicates the status or malfunction of the TPMS system and components.