Frelander 2. Manual - part 69

Vehicles fitted with TPMS can be visually identified by an external metal locknut and valve of the tire pressure sensor on
the road wheels. Vehicles without TPMS will have rubber tire valve.

Item

Part Number

Description

Tire valve and pressure sensor

Tire fitting/removal tool initial start position

High tire and bead tension area

Low tire and bead tension area

When removing the tire, the bead breaker must not be used within 90 degrees of the tire valve in each direction on each
side of the tire.

When using the tire removal machine, the fitting arm start position must be positioned as shown in the tire changing
illustration for each side of the tire. The wheel can then be rotated through 180 degrees in a counter-clockwise direction.
This will relieve tension from the tire bead allowing the remaining 180 degrees of the tire to be manually pulled from the
rim.

When refitting the tire, position the fitting arm as shown. Rotate the tire and take care that the bead on the low tension
side of the tire does not damage the sensor.

TREAD Act - NAS Only

Vehicles supplied to the North American markets must comply with the legislation of the Transport Recall Enhancement,
Accountability and Documentation (TREAD) act. Part of the requirement of the TREAD act is for the vehicle to display a
label, positioned on the driver's side 'B' pillar, which defines the recommended tire inflation pressure, load limits and
maximum load of passengers and luggage weight the vehicle can safely carry. This label will be specific to each individual
vehicle and will be installed on the production line.

This label must not be removed from the vehicle. The label information will only define the specification of the vehicle as
it came off the production line. It will not include dealer or owner fitted accessory wheels and tires of differing size from
the original fitment.

If the label is damaged or removed for body repair, it must be replaced with a new label specific to that vehicle. A new
label is requested from Land Rover parts and will be printed specifically for the supplied VIN of the vehicle.

TIRE PRESSURE MONITORING SYSTEM (TPMS)

Item

Part Number

Description

Battery junction box

Instrument cluster

RF receiver

Initiator

Central Junction Box (CJB)

Tire pressure sensor

The TPMS is a driver assistance system which assists the driver to maintain the tire pressures at the optimum level. The
TPMS is a standard fitment on North American Specification (NAS) vehicles and an optional fitment in other markets. The
TPMS system has the following benefits:

Improve fuel consumption
Maintain ride and handling characteristics
Reduce the risk of rapid tire deflation - which may be caused by under inflated tires
Comply with legislation requirements in relevant markets.

CAUTION: The TPMS is not intended as a replacement for regular tire pressure and tire condition checks and should

be considered as additional to good tire maintenance practices.

The TPMS measures the pressure in each of the tires on the vehicle (including the spare, if required) and issues warnings
to the driver if any of the pressures deviate from defined tolerances.

• NOTE: During a 'blow-out' a very rapid reduction in pressure is experienced. The system is not intended to warn the
driver of a 'blow-out', since 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.

The controlling software for the TPMS is located within the CJB. The software detects the following:

the tire pressure is below the recommended low pressure value - under inflated tire
the position of the tire on the vehicle.

The system comprises a Radio Frequency (RF) receiver, 4 initiators and 4 tire pressure sensors (5 if the spare wheel has a
sensor fitted).

The 4 initiators are hard wired to the CJB. 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 receiver which is located at the rear of the vehicle, behind the headlining. The RF receiver is connected
to the CJB on the Local Interconnect Network (LIN) bus. The received RF signals from the tire pressure sensors are passed
to the CJB on the LIN bus and contain identification, pressure, temperature and acceleration information for each wheel
and tire.

The TPMS software communicates with the instrument cluster via the medium speed Controller Area Network (CAN) bus to
provide the driver with appropriate warnings. The TPMS software 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 software using an 'auto-location' function. This function is fully
automatic and requires no input from the driver. The TPMS software 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
TPMS software can reject identifications from tire pressure sensors which do not belong to the vehicle
the spare wheel and one of the 'running' wheels on the vehicle have changed positions.

If a new tire pressure sensor is fitted on any 'running' wheel, the software 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).

• NOTE: The spare wheel is not fitted with a tire pressure sensor.

TPMS Operation

Each time the vehicle is driven the TPMS software activates each initiator in turn to transmit a LF 125 KHz signal to each
tire pressure sensor. The LF signal is received by the tire pressure sensor which responds by transmitting a 315 or 433
MHZ (depending on market) signal which is received by the RF receiver. The signal contains coded data which corresponds
to sensor identification, air pressure, air temperature and acceleration data. This is then passed to the CJB on the ISO
9141 K Line.

If the vehicle has been parked for more than 15 minutes and then driven at a speed of more than 12.5 mph (20 km/h), the
initiators each fire an LF signal in turn for 18 seconds in the following order:

Front LH
Front RH
Rear RH
Rear LH.

Each tire pressure sensor responds in turn which allows the TPMS software to establish the sensor positions at the start of
the drive cycle. This process is repeated up to three times but less if the sensor positions are already known. The process
is known as 'Auto Location' and takes 2 to 4 minutes to complete.

During this period the tire pressure sensors transmit at regular intervals, once every 5 seconds (once every 15 seconds on
NAS vehicles). For the remainder of the drive cycle the tire pressure sensors transmit once every 60 seconds or more often
if a change of tire pressure is sensed until the vehicle stops and the TPMS returns to the parking mode.

Once the wheel positions have been established, the initiators stop transmitting the LF signal and do not transmit again
until the vehicle has been parked for more than 15 minutes.

The warning appears in the instrument cluster message centre when the inflation pressure has fallen to 25% of the
nominal pressure. The displayed message will also include the position(s) of the affected wheel(s).

The TPMS enters 'Parking Mode' after the vehicle speed has been less than 20 km/h (12.5 mph) for 15 minutes. In parking
mode the tire pressure sensors transmit a coded RF signal once every 13 hours. If the tire pressure decreases by more

than 0.06 bar (1 lbf/in

), the sensor will transmit more often if pressure in the tire is being lost.

The spare wheel tire pressure sensor also transmits a signal once every 13 hours in the same manner as the 'running

wheels' when in parking mode. If the tire pressure decreases by more than 0.06 bar (1 lbf/in

), the sensor will transmit

more often if pressure in the tire is being lost.

Initiators

Four initiators are fitted to the vehicle. The front initiators are located near the front of the front wheel arches, behind the
fender splash shields. The rear initiators are located at the rear of the rear wheel arches, behind the fender splash shields.
Each initiator has a connector which connects to the vehicle body harness.

The initiator is a passive, LF transmitter. The initiators transmit their signals which are received by the tire pressure
sensors, prompting them to modify their mode status.

The TPMS energises each initiator in turn using LF drivers. The corresponding tire pressure sensor detects the LF signal and
responds by modifying the mode status within the RF transmission.

Tire Pressure Sensor

The TPMS uses active tire pressure sensors which are located on each wheel, inside the tire cavity. The sensor incorporates
the tire valve and is secured in the wheel by a nut on the outside of the wheel. The sensor contains a Printed Circuit Board
(PCB) which houses a Positive Temperature Co-efficient (PTC) sensor, a Piezo pressure sensor. a radio receiver and
transmitter and a lithium battery.

The tire pressure sensors use the PTC sensor and the Piezo sensor to periodically measure the pressure and temperature
of the air inside the tire. The data is transmitted by RF data signals at either 315 MHz or 433 MHz dependant on market
requirements.

The RF transmission from the sensor contains a unique identification code in its transmission data. This allows the TPMS
to identify the wheel on the vehicle. If the sensor is replaced on a 'running' wheel, the new sensor identification will be
learnt when the vehicle is driven at speed of more than 20 km/h (12.5 mph) for 15 minutes.

If a new sensor is fitted to the spare wheel, the identification for that sensor can be programmed into the TPMS using IDS.
The code is provided on a label with the complete tire, wheel and sensor assembly when new and is also printed on the
casing of each sensor. Alternatively, the spare wheel may also be programmed to the TPMS by using it as a 'running' wheel
for 15 minutes at a speed of more than 20 km/h (12.5 mph), then replacing it to the spare wheel location.

The tire pressure sensor can also detect when the wheel is rotating. In order to preserve battery power, the sensor uses
different transmission rates when the wheel is stationary or moving. The wheel speed required to change from stationary
to moving transmission rates is very low to allow for the requirement for slow off-road driving.

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