2002 LAND ROVER DISCOVERY engine

CORROSION PREVENTION AND SEALING
77-4-8 CORROSION PREVENTION
After refitting mechanical components, including hoses and pipes and other fixtures, mask off the brake discs and
apply a coat of approved underbody wax.
NOTE: Where repairs include the application of finish paint coats in the areas requiring underbody wax, carry out paint
operations before applying wax.
Cavity wax injection
Areas treated with cavity wax are shown in the previous figures. After repairs, always re-treat these areas with an
approved cavity wax. In addition, treat all interior surfaces which have been disturbed during repairs whether they
have been treated in production or not. This includes all box members, cavities and door interiors. It is permissible to
drill extra holes for access where necessary, provided these are not positioned in load-bearing members. Ensure that
such holes are treated with a suitable zinc rich primer, brushed with wax and then sealed with a rubber grommet.
Before wax injection, ensure that the cavity to be treated is free from any contamination or foreign matter. Where
necessary, clear out any debris using compressed air.
Ensure that cavity wax is applied AFTER the final paint process and BEFORE refitting any trim components.
During application, ensure that the wax covers all flange and seam areas and that it is adequately applied to all
repaired areas of both new and existing panels.
It should be noted that new panel assemblies and complete body shells are supplied without wax injection treatment.
Ensure that such treatment is carried out after repairs.
Effective cavity wax protection is vital. Always observe the following points:
lComplete all paint refinish operations before wax application;
lClean body panel areas and blow-clean cavities if necessary, before treatment;
lMaintain a temperature of 18
° C (64° F) during application and drying;
lCheck the spray pattern of injection equipment;
lMask off all areas not to be wax coated and which could be contaminated by wax overspray;
lRemove body fixings, such as seat belt retractors, if contamination is at all likely;
lMove door glasses to fully closed position before treating door interiors;
lTreat body areas normally covered by trim before refitting items;
lCheck that body and door drain holes are clear after the protective wax has dried;
lKeep all equipment clean, especially wax injection nozzles.
Underbody wax
The underbody wax must be reinstated following all repairs affecting floor panels. The wax is applied over paints and
underbody sealers.
Remove old underbody wax completely from a zone extending at least 200 mm (7.874 in) beyond the area where new
underbody sealer is to be applied.
Engine bay wax
Reinstate all protective engine bay wax disturbed during repairs using an approved material.
Where repairs have involved replacement of engine bay panels, treat the entire engine compartment including all
components, clips and other fixtures with an approved underbonnet lacquer or wax.

+ BODY SEALING MATERIALS, MATERIALS AND APPLICATIONS, Approved materials.

HEATING AND VENTILATION
DESCRIPTION AND OPERATION 80-3
Description
General
The heating and ventilation system controls the temperature and distribution of air supplied to the vehicle interior. The
system consists of an air inlet duct, heater assembly, distribution ducts and a control panel. An outlet vent is
incorporated at the rear of the cabin. Some diesel models also incorporate a fuel burning heater (FBH) system in the
engine coolant supply to the heater assembly.
Fresh or recirculated air flows into the heater assembly from the inlet duct. An electrical variable speed blower in the
inlet duct, and/or ram effect, forces the air through the system. Depending on the settings on the control panel, the air
is then heated and supplied through the distribution ducts to fascia and floor level outlets.

HEATING AND VENTILATION
DESCRIPTION AND OPERATION 80-5
Heater assembly
1Windscreen and side window air outlet
2Face level air outlet
3Casing
4Rear footwell air outlet
5Front footwell air outlet
6Drain outlet
7Air inlet8Engine coolant return
9Engine coolant feed
10Heater matrix
11RH temperature control cable
12Distribution control cable
13LH temperature control cable
The heater assembly heats and distributes air as directed by selections made on the control panel. The assembly is
installed on the vehicle centre-line, between the fascia and the engine bulkhead. The heater assembly consists of a
casing, formed from a series of plastic moldings, which contains a heater matrix and control flaps. Internal passages
integrated into the casing guide the air through the casing and separate it into two flows, one for the LH outlets and
one for the RH outlets. Two drain outlets at the bottom of the casing connect to overboard drain tubes installed in the
sides of the transmission tunnel.
Heater matrix
The heater matrix provides the heat source to warm the air being supplied to the distribution outlets. The heater matrix
is an aluminium two pass, fin and tube heat exchanger, installed in the RH side of the casing. Two aluminium tubes
attached to the heater matrix extend through the engine bulkhead to connect the heater assembly to the engine
coolant system. When the engine is running, coolant is constantly circulated through the heater matrix by the engine
coolant pump. On diesel models, the coolant flow is assisted by an electric pump while the FBH system is active.

HEATING AND VENTILATION
80-8DESCRIPTION AND OPERATION
Control panel
The controls for heating and ventilation are installed on a control panel in the centre of the fascia, below the radio.
Three rotary knobs control the LH and RH outlet temperatures and distribution. A slider switch controls blower speed.
A latching pushswitch controls the selection of fresh/recirculated air; an amber LED in the switch illuminates when
recirculated air is selected.
Graphics on the panel and the controls indicate the function and operating positions of the controls.
Outlet vent
The outlet vent promotes the free flow of heating and ventilation air through the cabin. The outlet vent is installed in
the RH rear quarter body panel and vents cabin air into the sheltered area between the rear quarter body panel and
the outer body side panel. The vent consists of a grille covered by soft rubber flaps and is effectively a non-return
valve. The flap opens and closes automatically depending on the differential between cabin and outside air pressures.
FBH system (diesel models only)
The FBH system is an auxiliary heating system that compensates for the relatively low coolant temperatures inherent
in the diesel engine. At low ambient temperatures, the FBH system heats the coolant supply to the heater assembly,
and maintains it within the temperature range required for good in-car heating performance. Operation is fully
automatic, with no intervention required by the driver.
The system consists of an air temperature sensor, a FBH fuel pump and a FBH unit. Fuel for the FBH system is taken
from the fuel tank, through a line attached to the fuel tank's fuel pump, and supplied via the FBH fuel pump to the FBH
unit. The connection on the fuel tank's fuel pump incorporates a tube which extends down into the tank. At the FBH
unit connection, the fuel line incorporates a self-sealing, quick disconnect coupling. In the FBH unit, the fuel delivered
by the FBH fuel pump is burned and the resultant heat output is used to heat the coolant. An ECU integrated into the
FBH unit controls the operation of the system at one of two heat output levels, 2.5 kW at part load and 5 kW at full load
Ambient temperature sensor
The ambient temperature sensor controls a power supply from the alternator to the FBH unit. The sensor is installed
on the RH support strut of the bonnet closing panel and contains a temperature sensitive switch that is closed at
temperatures below 5
°C (41 °F) and open at temperatures of 5 °C (41 °F) and above.

HEATING AND VENTILATION
80-10DESCRIPTION AND OPERATION
FBH unit
1Air inlet hose
2Electrical connectors
3Exhaust pipe
4Quick disconnect coupling5Coolant inlet hose
6Fuel supply line
7Circulation pump
8Coolant outlet hose
The FBH unit is installed on the bulkhead in the engine compartment, on the side opposite the brake servo, and is
connected in series in the coolant supply to the heater assembly. Two electrical connectors on the top of the FBH unit
connect to the vehicle wiring.
FBH unit connector pin details
Connector/Pin
No.Description Input/Output
C0925
2 K line (diagnostics) Input/Output
3 Alternator power supply Input
6 FBH fuel pump Output
C0926
1 Battery power supply Input
2Earth -

HEATING AND VENTILATION
80-12DESCRIPTION AND OPERATION
Circulation pump. The circulation pump is installed at the coolant inlet to the FBH unit to assist the coolant flow through
the FBH unit and the heater assembly. The pump runs continuously while the FBH unit is in standby or active
operating modes. While the FBH unit is inactive, coolant flow is reliant on the engine coolant pump.
Combustion air fan. The combustion air fan regulates the flow of air into the unit to support combustion of the fuel
supplied by the FBH pump. It also supplies the air required to purge and cool the FBH unit. Ambient air is supplied to
the combustion air fan through an air inlet hose containing a sound deadening foam ring.
Burner housing. The burner housing contains the burner insert and also incorporates connections for the exhaust
pipe, the coolant inlet from the circulation pump and the coolant outlet to the heater assembly. The exhaust pipe
directs exhaust combustion gases to atmosphere at the bottom of the engine compartment.
The burner insert incorporates the fuel combustion chamber, an evaporator and a glow plug/flame sensor. Fuel from
the FBH fuel pump is supplied to the evaporator, where it evaporates and enters the combustion chamber to mix with
air from the combustion air fan. The glow plug/flame sensor provides the ignition source of the fuel:air mixture and,
once combustion is established, monitors the flame.
ECU/heat exchanger. The ECU controls and monitors operation of the FBH system. Ventilation of the ECU is
provided by an internal flow of air from the combustion air fan. The heat exchanger transfers heat generated by
combustion to the coolant. A sensor in the heat exchanger provides the ECU with an input of heat exchanger casing
temperature, which the ECU relates to coolant temperature and uses to control system operation. The temperature
settings in the ECU are calibrated to compensate for the difference between coolant temperature and the heat
exchanger casing temperature detected by the sensor. Typically: as the coolant temperature increases, the coolant
will be approximately 7
°C (12.6 °F) hotter than the temperature detected by the sensor; as the coolant temperature
decreases, the coolant will be approximately 2
°C (3.6 °F) cooler than the temperature detected by the sensor.

HEATING AND VENTILATION
DESCRIPTION AND OPERATION 80-13
Operation
Air distribution
Turning the distribution knob on the control panel turns the control flaps in the heater assembly to direct air to the
corresponding fascia and footwell outlets.
Air temperature
Turning the LH or RH temperature knob on the control panel turns the related blend flaps in the heater assembly. The
blend flaps vary the proportion of air going through the cold air bypass and the heater matrix. The proportion varies,
between full bypass no heat and no bypass full heat, to correspond with the position of the temperature knob.
Blower speed
The blower can be selected off or to run at one of four speeds. While the ignition is on, when the blower switch is set
to positions 1, 2, 3, or 4, ignition power energises the blower relay, which supplies battery power to the blower. At
switch positions 1, 2 and 3, the blower switch also connects the blower to different earth paths through the resistor
pack, to produce corresponding differences of blower operating voltage and speed. At position 4, the blower switch
connects an earth direct to the blower, bypassing the resistor pack, and full battery voltage drives the blower at
maximum speed.
Fresh/Recirculated inlet air
When the recirculated air switch is latched in, the amber indicator LED in the switch illuminates and an earth is
connected to the recirculated air side of the fresh/recirculated air servo motor. The fresh/recirculated air servo motor
then turns the control flaps in the air inlet duct to close the fresh air inlet and open the recirculated air inlets.
When the latch of the recirculated air switch is released, the amber indicator LED in the switch extinguishes and the
earth is switched from the recirculated air side to the fresh air side of the fresh/recirculated air servo motor. The fresh/
recirculated air servo motor then turns the control flaps in the air inlet duct to open the fresh air inlet and close the
recirculated air inlets.
FBH system (where fitted)
The FBH system operates only while the engine is running and the ambient temperature is less than 5
°C (41 °F).
With the engine running and the ambient temperature below 5
°C (41 °F), the air temperature sensor connects the
alternator power supply to the ECU in the FBH unit. On receipt of the alternator power supply, the ECU starts the
circulation pump and, depending on the input from the temperature sensor in the heat exchanger, enters either a
standby or active mode of operation. If the heat exchanger casing temperature is 65
°C (149 °F) or above, the ECU
enters a standby mode of operation. If the heat exchanger casing temperature is below 65
°C (149 °F), the ECU enters
an active mode of operation. In the standby mode, the ECU monitors the heat exchanger casing temperature and
enters the active mode if it drops below 65
°C (149 °F). In the active mode, the ECU initiates a start sequence and
then operates the system at full or part load combustion to provide the required heat input to the coolant.
Start sequence
At the beginning of the start sequence the ECU energises the glow plug function of the glow plug/flame sensor, to
preheat the combustion chamber, and starts the combustion air fan at slow speed. After 30 seconds, the ECU
energises the FBH fuel pump at the starting sequence speed. The fuel delivered by the FBH fuel pump evaporates in
the combustion chamber, mixes with air from the combustion air fan and is ignited by the glow plug/flame sensor. The
ECU then progressively increases the speed of the FBH fuel pump and the combustion air fan to either part or full
load speed, as required by the system. Once full or part load speed is achieved, the ECU switches the glow plug/flame
sensor from the glow plug function to the flame sensing function to monitor combustion. From the beginning of the
start sequence to stable combustion takes approximately 90 seconds for a start to part load combustion and 150
seconds for a start to full load combustion.

HEATING AND VENTILATION
80-14DESCRIPTION AND OPERATION
Coolant temperature control
When the ECU first enters the active mode, it initiates a start to full load combustion. Full load combustion continues
until the heat exchanger casing temperature reaches 60
°C (140 °F), when the ECU decreases the speed of the FBH
fuel pump and the combustion air fan to half speed, to produce part load combustion. The ECU maintains part load
combustion while the heat exchanger casing temperature remains between 54 and 65
°C (129 and 149 °F). If the heat
exchanger casing temperature decreases to 54
°C (129 °F), the ECU switches the system to full load combustion
again. If the heat exchanger casing temperature increases to 65
°C (149 °F), the ECU enters a control idle phase of
operation.
On entering the control idle phase, the ECU immediately switches the FBH fuel pump off, to stop combustion, and
starts a timer for the combustion air fan. After a 2 minute cooldown period, the ECU switches the combustion air fan
off and then remains in the control idle phase while the heat exchanger casing temperature remains above 59
°C (138
°F). If the heat exchanger casing temperature decreases to 59 °C (138 °F), within 15 minutes of the ECU entering the
control idle phase, the ECU initiates a start to part load combustion. If more than 15 minutes elapse before the heat
exchanger casing temperature decreases to 59
°C (138 °F), the ECU initiates a start to full load combustion.
In order to limit the build-up of carbon deposits on the glow plug/flame sensor, the ECU also enters the control idle
phase if the continuous part and/or full load combustion time exceeds 72 minutes. After the cooldown period, if the
heat exchanger casing is still in the temperature range that requires additional heat, the ECU initiates an immediate
restart to part or full load combustion, as appropriate.
Shutdown
The FBH system is de-activated when the alternator power supply to the FBH unit is disconnected, either by the
engine stopping or, if the ambient temperature increases to 5
°C (41 °F) or above, by the contacts in the air
temperature sensor opening. If the system is active when the alternator power supply is disconnected, the ECU de-
energises the FBH fuel pump to stop combustion, but continues operation of the combustion air fan and the circulation
pump to cool down the FBH unit. The cool down time depends on the combustion load at the time the alternator power
input is disconnected.
Cool down times
Diagnostics
The ECU in the FBH unit monitors the system for faults. Any faults detected are stored in a volatile memory in the the
ECU, which can be interrogated by Testbook. A maximum of three faults and associated freeze frame data can be
stored at any one time. If a further fault is detected, the oldest fault is overwritten by the new fault.
The ECU also incorporates an error lockout mode of operation that inhibits system operation to prevent serious faults
from causing further damage to the system. In the error lockout mode, the ECU immediately stops the FBH fuel pump,
and stops the combustion air fan and circulation pump after a cool down time of approximately 2 minutes. Error lockout
occurs for start sequence failures and/or combustion flameouts, heat exchanger casing overheat and out of limit input
voltage. The error lockout mode can be cleared using Testbook, or by disconnecting the battery power supply for a
minimum of 10 seconds.
Start failure/flameout. If a start sequence fails to establish combustion, or a flameout occurs after combustion is
established, the ECU immediately initiates another start sequence. The start failure or flameout is also recorded by
an event timer in the ECU. The event timer is increased by one after each start failure or flameout, and decreased by
one if a subsequent start is successful. If the event timer increases to three (over any number of drive cycles), the
ECU enters the error lockout mode.
Heat exchanger casing overheat. To protect the system from excessive temperatures, the ECU enters the error
lockout mode if the heat exchanger casing temperature exceeds 105
°C (221 °F).
Out of limit voltage. The ECU enters the error lockout mode if the battery or alternator power input is less than 10.5
±
0.3 V for more than 20 seconds, or more than 15.5
± 0.5 V for more than 6 seconds.
Combustion load Cool down time, seconds
Part 100
Full 175