air conditioning LAND ROVER DISCOVERY 1999 Owner's Manual
[x] Cancel search | Manufacturer: LAND ROVER, Model Year: 1999, Model line: DISCOVERY, Model: LAND ROVER DISCOVERY 1999Pages: 1529, PDF Size: 34.8 MB
Page 346 of 1529
ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-47
ATC compressor clutch relay
The ATC compressor clutch relay is located in the engine compartment fuse box. It is a four pin normally open relay.
The relay must be energised to drive the ATC compressor clutch.
Input/Output
The ECM provides the earth for the relay coil to allow the relay contacts to close and the ATC clutch drive to receive
battery voltage. The ECM uses a transistor as a switch to generate an open circuit in the earth path of the relay coil.
When the ECM opens the earth path, the return spring in the relay will pull the contacts apart to shut down the ATC
clutch drive.
Input to the ATC clutch relay switching contacts is via fuse 6 located in the engine compartment fuse box. The relay
coils are supplied with battery voltage from the main relay, also located in the engine compartment fuse box. The earth
path for the relay coil is via pin 29 of the ECM C0657 connector. When the relay is energised the output from the
switching contacts goes directly to the ATC compressor clutch.
The ATC clutch relay can fail in the following ways:
lRelay open circuit.
lShort circuit to vehicle supply.
lShort circuit to vehicle earth.
lBroken return spring.
In the event of an ATC clutch relay failure, the ATC does not work.
Should a malfunction of the component occur, the following fault codes may be evident and can be retrieved by
TestBook.
P Code J2012 Description Land Rover Description
P1536 Air conditioning compressor request range/
performanceATC compressor clutch relay open circuit
P1537 Air conditioning compressor request low input ATC compressor clutch relay short to earth
P1538 Air conditioning compressor request high input ATC compressor clutch relay short to battery supply
Page 350 of 1529
ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-51
Conditions
The ECM calculates ignition timing using input from the following:
lCKP sensor.
lKnock sensors (KS).
lMAF sensor.
lTP sensor (idle only).
lECT sensor.
Function
At engine start up, the ECM sets ignition timing dependent on ECT information and starting rev/min from the CKP. As
the running characteristics of the engine change, the ignition timing changes. The ECM compares the CKP signal to
stored values in its memory, and if necessary advances or retards the spark via the ignition coils.
Ignition timing is used by the ECM for knock control.
Knock control
The ECM uses active knock control to prevent possible engine damage due to pre-ignition. This is achieved by
converting engine block noise into a suitable electrical signal that can be processed by the ECM. A major contributing
factor to engine 'knock' is fuel quality, the ECM can function satisfactorily on 91 RON fuel as well as the 95 RON fuel
that it is calibrated for.
Conditions
The ECM knock control system operates as follows:
lHot running engine.
l91 or 95 RON fuel.
Function
The ECM knock control uses two sensors located one between the centre two cylinders of each bank. The knock
sensors consist of piezo ceramic crystals that oscillate to create a voltage signal. During pre-ignition, the frequency
of crystal oscillation increases which alters the signal output to the ECM.
If the knock sensors detect pre-ignition in any of the cylinders, the ECM retards the ignition timing by 3° for that
particular cylinder. If this action stops the engine knock, the ignition timing is restored to its previous figure in
increments of 0.75°. If this action does not stop engine knock then the ECM retards the ignition timing a further 3° up
to a maximum of -15° and then restores it by 0.75° and so on until the engine knock is eliminated.
The ECM also counteracts engine knock at high intake air temperatures by retarding the ignition as above. The ECM
uses the IAT signal to determine air temperature.
Idle speed control
The ECM regulates the engine speed at idling. The ECM uses the idle air control valve (IACV) to compensate for the
idle speed drop that occurs when the engine is placed under greater load than usual. When the throttle is in the rest
position i.e. it has not been pressed, the majority of intake air that the engine consumes comes from the idle air control
valve.
IACV control idle speed
Conditions in which the ECM operates the IACV control idle speed is as follows:
lIf any automatic transmission gears other than P or N are selected.
lIf air conditioning is switched on.
lIf cooling fans are switched on.
lAny electrical loads activated by the driver.
Function
The idle air control valve utilises two coils that use opposing pulse width modulated (PWM) signals to control the
position of a rotary valve. If one of the circuits that supplies the PWM signal fails, the ECM closes down the remaining
signal preventing the idle air control valve from working at its maximum/ minimum setting. If this should occur, the idle
air control valve assumes a default idle position at which the engine idle speed is raised to 1200 rev/min with no load
placed on the engine.
Page 431 of 1529
COOLING SYSTEM - V8
26-2-16 REPAIRS
8.Remove 6 scrivets and remove LH and RH air
deflectors from front panel. Disconnect
multiplug of gearbox oil temperature sensor
(arrowed).
9.Remove nut and move horn aside. 10.Remove 2 bolts securing radiator LH and RH
upper mounting brackets to body panel and
remove brackets.
11.Remove 4 screws securing air conditioning
condenser LH and RH upper mounting
brackets to condenser.
12.Remove brackets with rubber mounts from
radiator extension brackets.
13.Position absorbent cloth under each cooler
hose to collect oil spillage.
14.Push against coupling release rings and
disconnect hoses from gearbox oil cooler.
CAUTION: Always fit plugs to open
connections to prevent contamination.
15. If fitted: Push against coupling release rings
and disconnect hoses from engine oil cooler.
Page 432 of 1529
COOLING SYSTEM - V8
REPAIRS 26-2-17
16.Remove radiator assembly.
17.Release clip and remove bottom hose from
radiator.
18.Remove 2 bolts and remove extension
brackets from radiator.
19.Remove 2 captive nuts from radiator.
20.Remove 2 screws and remove gearbox oil
cooler from radiator.
21. If fitted: Remove 2 screws and remove engine
oil cooler from radiator.
22.Remove 2 rubber mountings from radiator.
23.Remove sealing strip from bottom of radiator.
24.Remove 2 cowl retaining clips from radiator. Refit
1.Fit cowl retaining clips to radiator.
2.Fit sealing strip to radiator.
3.Fit rubber mountings to radiator.
4.Fit gearbox oil cooler to radiator and secure
with screws.
5. If fitted: Fit engine oil cooler to radiator and
secure with screws.
6.Fit captive nuts to radiator.
7.Fit extension brackets to radiator and secure
with bolts.
8.Fit bottom hose to radiator and secure with clip.
9.Fit radiator and engage lower mountings in
chassis.
10.Ensure connections are clean, then secure
hoses to oil coolers.
11.Fit air conditioning condenser brackets and
secure with screws.
12.Fit radiator upper mounting brackets and
secure with bolts.
13.Fit LH horn and secure with nut.
14.Fit air deflectors and secure with scrivets.
15.Connect multiplug of gearbox oil temperature
sensor.
16.Fit front grille.
+ EXTERIOR FITTINGS, REPAIRS,
Grille - front - up to 03MY.
17.Connect bottom hose to thermostat housing
and secure with clip.
18.Connect top hose to radiator and secure with
clip.
19.Connect bleed hose to radiator and fit clip.
20.Fit lower fan cowl and secure with screws.
21.Fit viscous fan.
+ COOLING SYSTEM - V8, REPAIRS,
Fan - viscous.
22.Top up gearbox oil.
23.Top up engine oil.
24.Refill cooling system.
+ COOLING SYSTEM - V8,
ADJUSTMENTS, Drain and refill.
Page 871 of 1529
BRAKES
70-18 DESCRIPTION AND OPERATION
The SLABS ECU continually calculates vehicle speed using the wheel speed inputs from all four ABS sensors. The
calculated vehicle speed is then used as a reference against which individual wheel speeds are monitored for
unacceptable acceleration or deceleration. The ABS sensor inputs are also used by the SLABS ECU to detect vehicle
deceleration rate, vehicle cornering rate and rough terrain.
The engaged forward gear and (on manual gearbox models) the clutch status are computed from the engine data
input, the engine speed input and vehicle speed. Reverse gear status is provided by an input from the reverse lamp
switch (manual gearbox models) or the BCU (automatic gearbox models). On automatic models, the BCU also
provides the neutral selected input.
In addition to controlling the brake related functions, the SLABS ECU:
lControls the operation of the self levelling suspension (SLS) system (where fitted).
+ REAR SUSPENSION, DESCRIPTION AND OPERATION, Description.
lOn V8 models, outputs a rough road signal to the ECM when traversing rough terrain.
lOutputs a vehicle speed signal.
The vehicle speed signal is output to the following systems (where fitted):
lActive Cornering Enhancement.
+ FRONT SUSPENSION, DESCRIPTION AND OPERATION, Description - ACE.
lAir conditioning.
+ AIR CONDITIONING, DESCRIPTION AND OPERATION, Description.
lCruise control.
+ ENGINE MANAGEMENT SYSTEM - Td5, DESCRIPTION AND OPERATION, Description.
+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
lEngine management.
+ ENGINE MANAGEMENT SYSTEM - Td5, DESCRIPTION AND OPERATION, Description.
+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
lIn-car entertainment.
+ IN CAR ENTERTAINMENT, DESCRIPTION AND OPERATION, Description.
lInstrument pack.
+ INSTRUMENTS, DESCRIPTION AND OPERATION, Description.
5 Front right inlet solenoid valve Output
6 Shuttle valve switches Input
7 Rear left outlet solenoid valve Output
8 Rear left inlet solenoid valve Output
9 Centre differential lock switch Input
10 Rear right outlet solenoid valve Output
11 Rear right inlet solenoid valve Output
12 Brake lamp relay Output
15 Return pump relay Output
C0655
7 Audible warning Output
10 Engine speed Input
Connector and pins not listed are either not used or used by the self levelling suspension system.
+ REAR SUSPENSION, DESCRIPTION AND OPERATION, Description.
Connector/Pin
No.Description Input/Output
Page 1088 of 1529
PANEL REPAIRS
REPAIRS 77-2-21
REPAIRS
Front bulkhead assembly
Remove
1.Disconnect both battery leads, negative lead
first.
2.Disconnect leads/multiplug from alternator.
3.Remove front wing.
+ EXTERIOR FITTINGS, REPAIRS,
Wing - front - up to 03MY.
4.Remove washer reservoir.
+ WIPERS AND WASHERS, REPAIRS,
Reservoir - washer - up to 03MY.
5. Models with A/C: Remove condensor.
+ AIR CONDITIONING, REPAIRS,
Condenser.
6. Diesel models: Remove gearbox fluid cooler.
7.Remove RH and LH headlamps.
+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
8.Release headlamp levelling motors and
position aside.
9.Release headlamp wiring and position aside.
10.Remove battery.
+ CHARGING AND STARTING,
REPAIRS, Battery.
11.Remove battery tray.
12.Remove air filter assembly.
+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Air filter assembly.
+ ENGINE MANAGEMENT SYSTEM -
V8, REPAIRS, Air cleaner assembly.
13.Remove 2 earth leads from LH of front
bulkhead.
14.Remove RH horn.
+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
15. Models with A/C: Release and remove A/C
pipes.
16.Remove RH and LH crush cans.
17.Remove bonnet release cable.
18.Support bonnet in open position
19.Remove bonnet locking mechanism.
20.Remove VIN plate.
21.Remove 2 bolts securing front bulkhead
assembly to chassis.
22.Remove centre braces.Repair
1.Remove existing panel(s), prepare panel joint
faces and install new panel(s) in accordance
with Panel Replacement Procedure. Punch or
drill holes in new panel for plug welding as
shown.
Refit
1.Fit centre braces.
2.Fit 2 bolts securing bulkhead to chassis and
tighten to 45 Nm (33 lbf.ft).
3.Fit VIN plate.
4.Fit bonnet locking mechanism.
5.Fit bonnet release cable.
6.Fit crush cans.
7. Models with A/C: Fit A/C pipes.
8.Fit RH horn.
+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
9.Fit 2 earth leads to LH of front bulkhead.
10.Fit air filter assembly.
+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Air filter assembly.
+ ENGINE MANAGEMENT SYSTEM -
V8, REPAIRS, Air cleaner assembly.
11.Fit battery tray.
12.Fit battery. Do not connect leads.
+ CHARGING AND STARTING,
REPAIRS, Battery.
13.Fit headlamp wiring and headlamp levelling
motors.
14.Fit RH and LH headlamps.
+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
15. Diesel models: Fit gearbox fluid cooler.
16. Models with A/C: Fit condensor.
+ AIR CONDITIONING, REPAIRS,
Condenser.
17.Fit washer reservoir.
+ WIPERS AND WASHERS, REPAIRS,
Reservoir - washer - up to 03MY.
Page 1090 of 1529
PANEL REPAIRS
REPAIRS 77-2-23
Bonnet locking platform
Remove
1.Disconnect both battery leads, negative lead
first.
2.Disconnect leads/multiplug from alternator.
3.Remove front bumper assembly.
+ EXTERIOR FITTINGS, REPAIRS,
Bumper assembly - front.
4. Models with A/C: Remove condensor.
+ AIR CONDITIONING, REPAIRS,
Condenser.
5. Diesel models: Remove gearbox fluid cooler.
6.Remove RH and LH headlamps.
+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
7.Remove RH and LH repeater lamps.
+ LIGHTING, REPAIRS, Lamp - front
repeater - up to 03MY.
8.Release headlamp wiring and position aside.
9.Remove battery.
+ CHARGING AND STARTING,
REPAIRS, Battery.
10.Remove battery tray.
11.Remove air filter assembly.
+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Air filter assembly.
+ ENGINE MANAGEMENT SYSTEM -
V8, REPAIRS, Air cleaner assembly.
12.Remove RH horn.
+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
13.Remove bonnet release cable.
14.Support bonnet in open position
15.Remove bonnet locking mechanism.
16.Remove VIN plate.
17.Remove centre braces.Repair
1.Remove existing panel(s), prepare panel joint
faces and install new panel(s) in accordance
with Panel Replacement Procedure. Punch or
drill holes in new panel for plug welding as
shown.
Refit
1.Fit centre braces.
2.Fit VIN plate.
3.Fit bonnet locking mechanism.
4.Fit bonnet release cable.
5.Fit RH horn.
+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
6.Fit air filter assembly.
+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Air filter assembly.
+ ENGINE MANAGEMENT SYSTEM -
V8, REPAIRS, Air cleaner assembly.
7.Fit battery tray.
8.Fit battery. Do not connect leads.
+ CHARGING AND STARTING,
REPAIRS, Battery.
9.Fit headlamp wiring.
10.Fit RH and LH repeater lamps.
+ LIGHTING, REPAIRS, Lamp - front
repeater - up to 03MY.
11.Fit RH and LH headlamps.
+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
12. Diesel models: Fit gearbox fluid cooler.
13. Models with A/C: Fit condensor.
+ AIR CONDITIONING, REPAIRS,
Condenser.
14.Fit bumper assembly.
+ EXTERIOR FITTINGS, REPAIRS,
Bumper assembly - front.
15.Connect leads/multiplug to alternator.
16.Connect battery leads, negative lead last.
Page 1091 of 1529
PANEL REPAIRS
77-2-24 REPAIRS
Front cross member
Remove
1.Disconnect both battery leads, negative lead
first.
2.Disconnect leads/multiplug from alternator.
3.Remove washer reservoir.
+ WIPERS AND WASHERS, REPAIRS,
Reservoir - washer - up to 03MY.
4. Models with A/C: Remove condensor.
+ AIR CONDITIONING, REPAIRS,
Condenser.
5. Diesel models: Remove gearbox fluid cooler.
6.Remove RH and LH headlamps.
+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
7.Release headlamp levelling motors and
position aside.
8.Release headlamp wiring and position aside.
9.Remove RH horn.
+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
10. Models with A/C: Release and remove A/C
pipes.
11.Remove RH and LH crush cans.
12.Remove 2 bolts securing front bulkhead
assembly to chassis.
13.Remove centre braces.
Repair
1.Remove existing panel(s), prepare panel joint
faces and install new panel(s) in accordance
with Panel Replacement Procedure. Punch or
drill holes in new panel for plug welding as
shown.Refit
1.Fit centre braces.
2.Fit 2 bolts securing bulkhead to chassis and
tighten bolts to 45 Nm (33 lbf.ft).
3.Fit crush cans.
4. Models with A/C: Fit A/C pipes.
5.Fit RH horn.
+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
6.Fit headlamp wiring and headlamp levelling
motors.
7.Fit RH and LH headlamps.
+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
8. Diesel models: Fit gearbox fluid cooler.
9. Models with A/C: Fit condensor.
+ AIR CONDITIONING, REPAIRS,
Condenser.
10.Fit washer reservoir.
+ WIPERS AND WASHERS, REPAIRS,
Reservoir - washer - up to 03MY.
11.Connect leads/multiplug to alternator.
12.Connect battery leads, negative lead last.
Page 1092 of 1529
PANEL REPAIRS
REPAIRS 77-2-25
Headlamp mounting panel - RH
Remove
1.Disconnect both battery leads, negative lead
first.
2.Disconnect leads/multiplug from alternator.
3.Remove front bumper assembly.
+ EXTERIOR FITTINGS, REPAIRS,
Bumper assembly - front.
4. Models with A/C: Remove condensor.
+ AIR CONDITIONING, REPAIRS,
Condenser.
5. Diesel models: Remove gearbox fluid cooler.
6.Remove RH headlamp.
+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
7.Remove RH repeater lamp.
+ LIGHTING, REPAIRS, Lamp - front
repeater - up to 03MY.
8.Release headlamp levelling motor and position
aside.
9.Release headlamp wiring and position aside.
10.Remove battery and battery tray.
+ CHARGING AND STARTING,
REPAIRS, Battery.
11.Remove horn.
+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
12.Remove RH crush can.
13.Remove 2 bolts securing front bulkhead
assembly to chassis.
14.Remove RH centre brace.Repair
1.Remove existing panel(s), prepare panel joint
faces and install new panel(s) in accordance
with Panel Replacement Procedure. Punch or
drill holes in new panel for plug welding as
shown.
Refit
1.Fit centre brace.
2.Fit 2 bolts securing bulkhead to chassis and
tighten bolts to 45 Nm (33 lbf.ft).
3.Fit crush can.
4. Models with A/C: Fit A/C pipes.
5.Fit horn.
+ ALARM SYSTEM AND HORN,
REPAIR, Vehicle horn.
6.Fit battery and battery tray. Do not connect
leads.
+ CHARGING AND STARTING,
REPAIRS, Battery.
7.Fit headlamp wiring and headlamp levelling
motors.
8.Fit repeater lamp.
+ LIGHTING, REPAIRS, Lamp - front
repeater - up to 03MY.
M77 1741A
Page 1093 of 1529
PANEL REPAIRS
77-2-26 REPAIRS
9.Fit headlamp.
+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
10. Diesel models: Fit gearbox fluid cooler.
11. Models with A/C: Fit condensor.
+ AIR CONDITIONING, REPAIRS,
Condenser.
12.Fit bumper assembly.
+ EXTERIOR FITTINGS, REPAIRS,
Bumper assembly - front.
13.Connect leads/multiplug to alternator.
14.Connect battery leads, negative lead last.
Headlamp mounting panel - LH
Remove
1.Disconnect both battery leads, negative lead
first.
2.Disconnect leads/multiplug from alternator.
3.Remove washer reservoir.
+ WIPERS AND WASHERS, REPAIRS,
Reservoir - washer - up to 03MY.
4. Models with A/C: Remove condensor.
+ AIR CONDITIONING, REPAIRS,
Condenser.
5. Diesel models: Remove gearbox fluid cooler.
6.Remove headlamp.
+ LIGHTING, REPAIRS, Headlamp - up
to 03MY.
7.Remove repeater lamp.
+ LIGHTING, REPAIRS, Lamp - front
repeater - up to 03MY.
8.Release headlamp levelling motor and position
aside.
9.Release headlamp wiring and position aside.
10.Remove air filter assembly.
+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Air filter assembly.
+ ENGINE MANAGEMENT SYSTEM -
V8, REPAIRS, Air cleaner assembly.
11.Remove 2 earth leads from LH of front
bulkhead.
12.Release and remove A/C pipes.
13.Remove crush can.
14.Remove bonnet release cable.
15.Remove 2 bolts securing front bulkhead
assembly to chassis.
16.Remove centre brace.