1999 LAND ROVER DISCOVERY warning light

ENGINE MANAGEMENT SYSTEM - V8
18-2-56 DESCRIPTION AND OPERATION
Function
Input for the rough road signal is measured via pin 34 of connector C0637 of the ECM. The SLABS ECU generates
a PWM signal that varies in accordance with changing road conditions. The rough road PWM signal operates at a
frequency of 2.33 Hz ± 10%. The significance of changes in the PWM signal are shown in the following table:
The rough road signal can fail in the following ways:
lHarness or connector damage
lSLABS failure — wheel speed sensor
A rough road signal failure may be evident from the following:
lHDC / ABS warning light on
Should a malfunction of the rough road signal occur, the following fault codes may be evident and can be retrieved
by TestBook:
Hill Descent Control (HDC) signal
The ECM transmits throttle angle, engine torque, engine identification (Td5 or V8), and transmission type (automatic
or manual) data to the SLABS ECU to support the Hill Descent Control system. The information is transmitted via a
0 – 12V pulse width modulated (PWM) signal at a frequency of 179.27 Hz.
Function
The HDC signal output from the ECM is via pin 29 of connector C0636. The ECM generates a PWM signal that varies
in pulse width in accordance with changing throttle angle or engine torque. The throttle angle data is transmitted on
pulses 1, 3, 5 and 37. The engine torque data is transmitted on pulses 2,4,6 and 38. The engine and transmission
information is transmitted on pulse 39. A synchronising pulse is transmitted after every 39th pulse.
The HDC signal can fail in the following ways:
lHarness or connector damage
A HDC signal failure may be evident from the following:
lHDC / ABS warning light on
lHDC inoperative
lAudible warning
Should a malfunction of the HDC signal occur, the following fault codes may be evident and can be retrieved by
TestBook:
PWM signal Indication
<10% Electrical short circuit to ground
25% ± 5 % Smooth road
50% ± 5 % SLABS error
75% ± 5% Rough road
>90% Electrical short circuit to battery voltage
P Code J2012 Description Land Rover Description
P1590 ABS rough road signal circuit malfunction Hardware is OK, but SLABS ECU is sending an error
signal
P1591 ABS rough road signal circuit low Signal from SLABS ECU short circuit to earth
P1592 ABS rough road signal circuit high Signal from SLABS ECU short circuit to vehicle battery
supply
P Code J2012 Description Land Rover Description
P1663 Throttle angle/Torque signal circuit malfunction SLABS HDC link open circuit
P1664 Throttle angle/Torque signal circuit low SLABS HDC link short circuit to ground
P1665 Throttle angle/Torque signal circuit high SLABS HDC link short circuit to battery voltage

TRANSFER BOX - LT230SE
41-28 REPAIRS
28.Remove 4 bolts and nut, remove gearbox RH
mounting.
29.With assistance, remove transfer box from
gearbox.
30.Remove input shaft oil seal.

+ TRANSFER BOX - LT230SE,
REPAIRS, Oil seal - input shaft.
Refit
1.Fit new input shaft oil seal.

+ TRANSFER BOX - LT230SE,
REPAIRS, Oil seal - input shaft.
2.Clean transfer box to gearbox mating faces.
3.Raise transfer box on jack and align to guide
studs LRT-41-009.
4.Clean transfer box to gearbox bolt threads.
5.Apply sealant, Part No. STC 50552 to bolt and
stud threads.
6.Fit and lightly tighten 2 bolts and nut securing
transfer box to gearbox. If new stud is to be
fitted, apply sealant, Part No. STC 50552 to
stud threads and tighten to 45 Nm (33 lbf.ft).
7.Remove guide studs, fit and lightly tighten
remaining 3 bolts.
8.Tighten bolts and nut by diagonal selection to
45 Nm (33 lbf.ft).
9.Position gearbox RH mounting and tighten
bolts to 85 Nm (63 lbf.ft).
10.Tighten gearbox RH mounting nut to 48 Nm
(35 lbf.ft).
11.Remove 4 bolts securing support plate to
gearbox jack.
12.Remove 4 bolts securing support plate LRT-99-
010 to transfer box and remove plate.
13.Clean bottom plate bolt threads.
14.Apply sealant, Part No. STC 50552 to threads
of 4 bottom plate bolts.
15.Fit 4 bolts securing bottom plate to transfer box
and tighten to 25 Nm (18 lbf.ft).
16.Position breather pipe and secure to bulkhead
clip.
17.Connect multiplug to reverse light switch. 18. Up to 03 Model Year - if fitted : Connect
Lucars to differential lock switch and multiplugs
to high/low ratio switch and neutral sensor.
19. 03 Model Year onwards - if fitted: Connect
differential lock warning lamp multiplugs,
secure harness.
20.Position high/low ratio selector cable and
secure with clevis pin and 'C' clip.
21.Position differential lock selector cable to
differential lock selector cable abutment
bracket and tighten locknuts sufficiently to
retain cable.
22. If fitted: Fit differential lock selector cable to
transfer gearbox and secure with clevis pin.
23. If fitted: Adjust differential lock selector cable.

+ TRANSFER BOX - LT230SE,
ADJUSTMENTS, Cable - selector -
differential lock - adjust.
24. Models fitted with high/low shift interlock
solenoid: Position interlock solenoid harness
to high/low shift cable, fit sleeve around cable
and harness; secure sleeve.
25. Models fitted with high/low shift interlock
solenoid: Connect solenoid multiplug to main
harness and secure multiplug to bracket.
26.Clean handbrake and mating face.
27.Position handbrake back plate and tighten
bolts to 75 Nm (55 lbf.ft).
28.Clean handbrake drum.
29.Fit handbrake drum and tighten retaining
screw.
30.Fit front propeller shaft.

+ PROPELLER SHAFTS, REPAIRS,
Propeller shaft - front.
31.Fit rear propeller shaft.

+ PROPELLER SHAFTS, REPAIRS,
Propeller shaft - rear.
32.Clean exhaust silencer and mating face.
33.Position silencer, fit new gasket , connect
mounting rubbers and tighten nuts to 40 Nm
(30 lbf.ft).
34.Refill transfer box with oil.

+ MAINTENANCE, PROCEDURES,
Transfer box.
35.Fit front exhaust pipe.

+ MANIFOLDS AND EXHAUST
SYSTEMS - Td5, REPAIRS, Pipe - front.

TRANSFER BOX - LT230SE
41-32 REPAIRS
Refit
1.Fit new input shaft oil seal.

+ TRANSFER BOX - LT230SE,
REPAIRS, Oil seal - input shaft.
2.Clean transfer box to gearbox mating faces.
3.Raise transfer box on jack and align to guide
studs LRT-41-009.
4.Clean transfer box to gearbox bolt threads.
5.Apply sealant, Part No. STC 50552 to bolt and
stud threads.
6.Fit and lightly tighten 2 bolts and nut securing
transfer box to gearbox. If new stud is to be
fitted, apply sealant, Part No. STC 50552 to
stud threads and tighten to 45 Nm (33 lbf.ft).
7.Remove guide studs, fit and lightly tighten 3
bolts.
8.Tighten bolts and nut by diagonal selection to
45 Nm (33 lbf.ft.
9.Position gearbox RH mounting and tighten
bolts to 85 Nm (63 lbf.ft).
10.Tighten gearbox RH mounting nut to 48 Nm
(35 lbf.ft).
11.Fit nut to LH mounting and tighten to 48 Nm (35
lbf.ft).
12.Remove 4 bolts securing support plate to
gearbox jack.
13.Remove 4 bolts securing support plate LRT-99-
010 to transfer box and remove plate.
14.Clean threads of bottom plate bolts.
15.Apply sealant, Part No. STC 50552 to threads
of 4 bottom plate bolts.
16.Fit 4 bolts securing bottom plate and tighten to
25 Nm (18 lbf.ft).
17.Using new washers position breather pipe and
tighten banjo bolt.
18.Connect multiplug to transfer box neutral switch
and secure harness.
19. Up to 03 Model Year - if fitted : Connect
Lucars to differential lock switch and multiplugs
to high/low ratio switch and neutral sensor.
20. 03 Model Year onwards - if fitted: Connect
differential lock warning lamp multiplugs,
secure harness.
21.Connect multiplug to reverse lamp switch.
22. If fitted: Connect Lucars to oil temperature
switch.
23.Position high/low ratio selector cable and
secure with 'C' clip and clevis pin.
24. If fitted: Position differential lock selector cable
to differential lock selector cable abutment
bracket and tighten locknuts sufficiently to
retain cable.
25. If fitted: Fit differential lock selector cable to
transfer gearbox and secure with clevis pin.
26. If fitted: Adjust differential lock selector cable.

+ TRANSFER BOX - LT230SE,
ADJUSTMENTS, Cable - selector -
differential lock - adjust.27. Models fitted with high/low shift interlock
solenoid: Position interlock solenoid harness
to high/low shift cable, fit sleeve around cable
and harness; secure sleeve.
28. Models fitted with high/low shift interlock
solenoid: Connect solenoid multiplug to main
harness and secure multiplug to bracket.
29.Secure cable to fuel pipes with new cable ties.
30.Clean handbrake back plate and mating face.
31.Position handbrake back plate, fit bolts and
tighten to 75 Nm (55 lbf.ft).
32.Clean handbrake drum.
33.Fit handbrake drum and tighten retaining
screw.
34.Fit front propeller shaft.

+ PROPELLER SHAFTS, REPAIRS,
Propeller shaft - front.
35.Fit rear propeller shaft.

+ PROPELLER SHAFTS, REPAIRS,
Propeller shaft - rear.
36.Clean exhaust silencer and tail pipe mating
faces.
37.Position silencer and secure on mountings,
using a new gasket align to tail pipe, fit nuts
and tighten to 25 Nm (18 lbf.ft).
38.Position rear cross member, fit bolts and
tighten to 26 Nm (19 lbf.ft).
39.Refill transfer box with oil.

+ MAINTENANCE, PROCEDURES,
Transfer box.
40.Fit front exhaust pipe.

+ MANIFOLDS AND EXHAUST
SYSTEMS - V8, REPAIRS, Front pipe.

FRONT SUSPENSION
REPAIRS 60-35
6.Apply a 3 mm (0.125 in) wide bead of sealant,
Part No. STC 50554 around drive shaft
circumference, as illustrated.
7.Ensure ABS harness is located in cut out in
steering knuckle.
8.Fit wheel hub to drive shaft and align steering
knuckle. The sealant will smear along the
length of the splines as the wheel hub is fitted
to the drive shaft.
9.Fit wheel hub bolts and tighten to 100 Nm (74
lbf.ft).
10.Fit new drive shaft nut and lightly tighten.
11.Fit front brake disc.

+ BRAKES, REPAIRS, Brake disc -
front.
12.With assistance, final tighten drive shaft nut to
490 Nm (360 lbf.ft). Stake drive shaft nut. The
drive shaft nut must be tightened before
sealant has cured.
13.Secure ABS sensor harness to brackets and
secure grommet to inner wing.
14.Fit road wheel and tighten nuts to 140 Nm (103
lbf.ft).
15.Remove stand(s) and lower vehicle.
16.Connect ABS sensor multiplug.
Damper - front
$% 60.30.02
Remove
1.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove road wheel.
3. RH damper: Release coolant reservoir and
position aside.
4.Loosen through bolt securing damper to turret.
WARNING: Make sure the axle cannot move
when the damper is disconnected. The
damper limits the downward movement of
the axle. If the axle is not restrained,
disconnecting the damper will allow
unrestricted movement which may cause
personal injury or damage to equipment.
M51 0058

BRAKES
70-20 DESCRIPTION AND OPERATION
Operation
Refer to illustration.

+ BRAKES, DESCRIPTION AND OPERATION, Brake system control diagram.
When the ignition is switched on, the SLABS ECU performs a check of the brake related warning lamps as part of the
power up procedure. The warning lamps are illuminated for approximately 3 seconds and then extinguished. If a fault
warning lamp remains illuminated after the lamp check, a fault has been detected and repair action is required.
ABS
The ABS function prevents the road wheels locking during brake application, thus maintaining vehicle stability even
under emergency conditions.
WARNING: ABS is an aid to retaining steering control and stability while braking:
lABS cannot defy the natural laws of physics acting on the vehicle.
lABS will not prevent accidents resulting from excessive cornering speeds, following another vehicle too
closely, aquaplaning, etc.
lThe additional control provided by ABS must never be exploited in a dangerous or reckless manner
which could jeopardise the safety of driver or other road users.
lThe fitting of ABS does not imply that the vehicle will always stop in a shorter distance.
NOTE: During normal braking the feel of the brake pedal on vehicles equipped with ABS will be the same as that on
non ABS vehicles. During anti-lock braking operation the driver will experience feedback in the form of a pulsating
brake pedal and solenoid/pump motor noise from the ABS modulator.
The anti-lock braking function is automatically enabled whenever the ABS modulator is in the normal braking mode.
While the anti-lock braking function is enabled, if the SLABS ECU detects a wheel decelerating faster than the
average and at the calibrated wheel slip limit for ABS operation, it operates the ABS modulator in the ABS braking
mode for the affected wheel.
EBD
The EBD function optimises the distribution of hydraulic pressure between the front and rear axles, under all vehicle
load configurations and road conditions, to maintain vehicle stability during braking. EBD operates in forward and
reverse and is automatically enabled whenever the ABS modulator is in the normal braking mode at vehicle
deceleration rates of 0.3 g and above (i.e. medium to high brake pedal loads). EBD operation is similar to that of ABS,
but is calibrated to intervene at lower wheel slip limits and operates the brakes in axle pairs instead of individually.
During braking, if the SLABS ECU detects the wheels of one axle going slower than those of the other axle, i.e. a
potential wheel slip situation, it signals the ABS modulator to close the inlet solenoid valve for the brakes of the slower
wheels. This prevents any further increase in hydraulic pressure to those brakes, while allowing the hydraulic pressure
to the brakes on the other axle to increase and so maximise the overall braking effort. If the wheel speeds of the axle
being subjected to EBD control return within the calibrated wheel slip limits, the SLABS ECU signals a stepped
opening of the inlet solenoid valves, which allows a progressive increase of hydraulic pressure to the related brakes.
Operation of EBD is detectable from a stiffening of brake pedal movement as the inlet solenoid valves close and a
slight pulsing of the brake pedal as the inlet solenoid valves open. EBD operation ceases immediately the brake pedal
is released.
The wheel slip limit for EBD operation varies with vehicle speed. During normal operation, the inlet solenoid valves
always operate in axle pairs, with only one axle pair closed at any one time. Since the most lightly loaded wheel during
a braking manoeuvre will usually be the first to reach the slip limit, under most vehicle load configurations and road
conditions EBD control occurs on the trailing axle. However, EBD control can occur on the leading axle or switch
between axles during the braking manoeuvre.

SCREENS
76-4-4 REPAIRS
15.Apply a continuous bead of sealant to sealant
face on screen as shown.
16.With assistance, lift screen into place and align
to screen supports and tape. Ensure top
finisher is located into correct position. Lightly
press glass to fully seat sealer.
CAUTION: Do not apply heavy pressure to
the sides of the windscreen. Lightly press
windscreen from centre outwards until
edges are to required gap. Pushing sides
into position can bend windscreen and lead
to cracking in service.
17.Remove protective covers and tape.
18.Test sealer for leaks, apply additional sealer if
necessary. If water is used, allow sealer to dry
before testing. Spray water around glass and
check for leaks. Mark any area that leaks. Dry
glass and sealer then apply additional sealer.
19.Fit interior mirror to slug.
20.If applicable, connect screen heater multiplugs.
21.Fit air intake plenum.

+ HEATING AND VENTILATION,
REPAIRS, Plenum Air Intake.
CAUTION: A curing time of 6 hours is
desirable. During this time leave a window
open to ventilate the vehicle interior. If the
vehicle must be used before the curing time
has elapsed, do not drive at speed or slam
the doors with the windows closed.
CAUTION: Vehicles fitted with a passenger
airbag should not be driven for 24 hours.
Glass - body side - rear
$% 76.81.18
Introduction
The following equipment is required:
lCutting wire and handles.
lKent cutting knife.
lGlazing knife.
lWindscreen repair kit.
lSealant applicator gun.
lSuction cups.
lA felt covered table or stand to support glass.
WARNING: Wear protective gloves when
handling glass, solvents and primers.
WARNING: Wear suitable eye protection when
removing and refitting glass.
Remove
1.If fitted, disconnect coaxial cable from terminal
on glass.
2.Fit protection to exterior body work adjacent to
glass.
3.Cover body panels adjacent to glass.
4.Fit protection to internal trim adjacent to glass.
5.Cover interior of vehicle with protective sheet.

SCREENS
76-4-6 REPAIRS
Glass - alpine light
$% 76.81.52
Introduction
The following equipment is required:
lCutting wire and handles.
lKent cutting knife.
lGlazing knife.
lWindscreen repair kit.
lSealant applicator gun.
lSuction cups.
lA felt covered table or stand to support glass.
WARNING: Wear protective gloves when
handling glass, solvents and primers.
WARNING: Wear suitable eye protection when
removing and refitting glass.
Remove
1.Fit protection to exterior body work adjacent to
glass.
2.Fit cover over adjacent body work.
3.Fit protection to internal trim adjacent to glass.
4.Cover interior of vehicle with protective sheet.
5.From outside of vehicle, use a Kent knife and
carefully cut through sealant to release glass
from body. Any remaining sealant not
accessible with Kent knife can be severed
using cutting wire or knife.
CAUTION: Hold the cutting wire as close to
the glass as possible to prevent damage to
the body and surrounding trim.
6.Remove glass.
CAUTION: Lay glass on felt covered
supports and be careful not to damage the
obscuration band. Do not stand on edge as
this can cause chips which subsequently
develop into cracks.Refit
1.Carefully remove sealant from body to leave a
smooth surface.
2.With assistance, fit glass without sealant to
body and apply masking tape to establish
reference marks as an alignment aid.
3.Remove glass and place aside.
4.Clean body and sealant face on glass with
solvent.
CAUTION: Do not touch cleaned or primed
surfaces with fingers.
5.Apply etch primer to any bare metal on body.
6.Apply glass primer to sealant face on glass and
allow to cure.
7.Apply primer over etch primer on body.
8.Apply activator over old sealant on body.
9.Allow activator to cure.
10.Fit pre-cut nozzle to sealant cartridge, remove
lid, shake out crystals, and fit cartridge to
applicator gun. If necessary modify the nozzle
to achieve required bead section.
11.Apply a continuous bead of sealant to sealant
face on glass as shown.

AIR CONDITIONING
82-14DESCRIPTION AND OPERATION
Display outputs
1LH temperature
2Economy mode
3Recirculated air
4Automatic mode5Manual distribution
6RH temperature
7Blower speed
8External air temperature
Outputs on the display are shown at full brightness when the exterior lights are off, and dimmed when the exterior
lights are on.
LH temperature. Illuminates to show the LH temperature selection, the temperature scale or that the ATC ECU is in
diagnostic mode.
Economy mode. Illuminates when the compressor is manually selected off with the ECON switch.
Recirculated air. Illuminates when the inlet air is manually selected to recirculated mode.
Automatic mode. Illuminates the AUTO legend and related symbol(s) when the blower speed, air distribution or
temperature control are in the automatic mode.
Manual distribution. Illuminates the appropriate symbol(s) to show the manually selected air distribution. Also
illuminates in the automatic modes when one of the temperatures is set to LO or HI.
RH temperature. Illuminates to show the RH temperature selection, external air temperature or diagnostic fault code.
Blower speed. Illuminates when the blower speed is manually selected. Also illuminates in the automatic modes when
one of the temperatures is set to LO or HI.
External air temperature. EXT illuminates to show that external air temperature is selected on.
All temperature indications on the display are in either °C or °F. For 1 second after the system is first switched on, the
display shows only °C or °F, in the LH temperature window, to indicate which temperature scale is in use. After 1
second, the °C or °F indication goes off and the display shows all relevant outputs.
Temperature conversion: While the system is on, the temperature indications on the display can be switched between
the two scales by pressing and holding the fresh/recirculated air switch, then pressing and holding the A/C on/off
switch until the audible warning sounds (approximately 3 seconds).