DESCRIPTION & OPERATION
The purpose of the Tire Pressure Monitoring System (TPMS) is to assist the driver in maintaining the vehicle's tire pressures at the optimum level in order to improve fuel consumption, maintain ride and handling characteristics, reduce the risk of rapid tire deflation caused by under inflated tires and comply with legislation in relevant markets.
The TPMS measures the pressure in each of the tires on the vehicle and issues warnings to the driver if any of the pressures deviate from the established amounts.
NOTE:
- The system is not intended to warn the driver of a tire 'blow out'. It is not possible to give the driver sufficient warning that such an event is occurring, due to its short duration. The design of the TPMS is to assist the driver in keeping the tires at the correct pressure, which will tend to reduce the likelihood of a tire 'blow out' occurring.
- TPMS is inhibited when the vehicle is in 'delivery' mode.
A single TPMS hardware configuration is used. TPMS status information is relayed to the driver with a message displayed in the Instrument Cluster (IC) message center and an amber warning indicator.
The 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 Radio Frequency (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 RF receiver located in the Tire Pressure Monitoring System Control Module (TPMSCM) behind the front 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' information 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. The sensor must be tightened to the correct torque value as given in the service repair 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 (JLR) approved diagnostic equipment. That wheel is not monitored until it is programmed, or until the wheel is learned by the vehicle, which can take up to 15 minutes. The identification code is on a label with the complete wheel and tire assembly when new and is printed on the casing of each sensor. In order to conserve battery power, the TPMSCM uses different RF transmission rates when the wheel is stationary or moving. The wheel speed required to change between stationary and moving transmission rates is very low to allow for slow off road driving.
MEMORIZING THE TIRE PRESSURE SENSOR ID
The TPMS locates the position of the tire automatically. This function requires no manual intervention by the driver. The TPMS automatically learns the position of tires on the vehicle if the tire pressure sensors or their positions are changed on the vehicle. The tire learn and location process is ready to start when the vehicle has been stationary, or is travelling at less than 20 km/h (12.5 mph) 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 timer is resumed. If the vehicle speed remains below 20 km/h (12.5 mph) for more than 15 minutes, the timer is set to zero and the process starts again. The TPMS can automatically detect, under all operating conditions, the following:
- If one or more tire pressure sensors have been replaced.
- If one or more tire pressure sensor identifications are missing.
- If one or more 'alien' identifications are being received. (The TPMS will reject these signals.)
- Identifications from tire pressure sensors that do not belong to the vehicle.
- If one of the tires in use on the vehicle has changed position on the vehicle.
- If one or more incompatible tire pressure sensors have been installed.
If the tire pressure sensors installed to the running wheels are changed, the TPMS can learn the new sensor identifications automatically. The learn function requires no manual intervention by the driver.
TIRE PRESSURE SENSOR REMOVAL AND INSTALLATION
Removal
WARNING: The valve seal and steel washer must be replaced each time a tire is changed to avoid seal failure. The seal and washer must be replaced if the sensor is removed. Removal of the sensor retaining nut must be regarded as sensor removal. The valve cap must always be in place except when inflating, releasing or checking pressure.
NOTE: If the sensor is installed on a running wheel, the new sensor identification will be learned when the vehicle is first driven. If a new sensor is installed to the spare wheel, the identification for that sensor must be programmed into the TPMS module using Land Rover approved diagnostic equipment. The identification code is provided on a label with the complete assembly and is also printed on the casing of each sensor.
1) Raise and support the vehicle.
2) Remove the wheel and tire assembly.
CAUTION: To avoid damage to the tire low pressure sensor, release the tire bead from the wheel, 180 degrees from the valve.
3) Remove the tire from the wheel.
NOTE: Discard the nut.
4) Remove the sensor retaining nut and then remove the sensor and valve assembly
5) Remove and discard the seal and washer.
Installation
CAUTION:
- Do not use compressed air to clean the sensor. Do not clean the sensor with solvents or cleaning agents of any type, use a clean dry cloth.
- Make sure that the mating faces are clean and free of foreign material.
1) Inspect the components, renew if damaged.
CAUTION: Do not apply any lubricant to the new valve.
2) Install a new washer, seal and retaining nut making sure the valve remains pressed fully onto its seat.
3) Install the tire and balance the wheel.
4) Install the wheel and tire assembly.
TORQUE SPECIFICATIONS
DESCRIPTION NM LB-FT
Road wheel nuts 140 103
Tire low pressure sensor 8 6
