1999 LAND ROVER DISCOVERY ABS

NAVIGATION SYSTEM
87-2 DESCRIPTION AND OPERATION
Description
General
The navigation system provides audio and visual route guidance to help the driver reach a selected destination. The
system is an optional fit consisting of a Traffic Pro navigation computer and antenna, manufactured by Harman/
Becker Automotive Systems, which are fitted in place of the In Car Entertainment (ICE) head unit and antenna.
Compact Disc (CD) and radio functions are incorporated into the navigation computer.
The navigation system allows the driver to choose between the shortest and fastest routes between the vehicle's
current position and a selected destination, and to select a stopover point in the journey and a route that avoids
motorways, ferries and toll roads. Directions to Points Of Interest (POI) e.g. airports, hospitals, petrol stations etc,
either local, national or in another country, can also be selected. A traffic jam function enables the driver to request
diversion instructions, around an obstructed part of the selected route, during the journey. A Traffic Management
Control (TMC) function, currently only available in some European countries, monitors traffic broadcasts and
automatically selects an alternative route during the journey if the original route is effected by a traffic jam, accident
or road works etc.
The position of the vehicle is determined by the navigation computer using a combination of vehicle sensor inputs and
radio signals from the 24 Global Positioning System (GPS) satellites orbiting the earth. The position of the vehicle is
then plotted on a digitised map, loaded into the navigation computer from a CD-ROM, to determine the journey route
and provide the route guidance.
The GPS satellite signals are used for initial determination of the vehicle's position and periodic position updates. The
vehicle sensor inputs are used to monitor the vehicle's direction of travel and distance travelled between position
updates from the GPS satellite signals. The vehicle sensor inputs consist of:
lA vehicle speed signal from the ABS ECU, to monitor the distance travelled and for automatic volume control.
lA reverse gear signal from the selector and inhibitor switch of the automatic gearbox, or reverse gear switch of
the manual gearbox, to enable the navigation computer to differentiate between forward and rearward movement
of the vehicle.
lA gyro in the navigation computer, to monitor changes of direction, i.e. steering inputs.
The signal from each GPS satellite contains information about satellite position, almanac data and time (almanac data
is the current status of the satellite). Signals from between five and 11 of the GPS satellites can be received at a given
point on the earth's surface at any one time. The number and quality of separate GPS satellite signals received also
varies with vehicle location. In hilly or tree lined areas, built up areas with tall buildings, multi-storey car parks,
garages, tunnels, bridges and during heavy rain/thunderstorms, signal reception of some or all of the GPS satellites
will be poor or non existent.
A minimum of three separate GPS satellite signals are required for the navigation computer to calculate a three
dimensional (3D) positional fix. When only two signals are being received, the navigation computer will calculate a
less accurate two dimensional (2D) positional fix. The more widely dispersed that the GPS satellites are, the more
accurate the positional fix. The navigation computer can store information from a maximum of 12 GPS satellites at
any one time. When more than three signals are stored, the navigation computer selects the three most widely
dispersed signals for the position calculation.
GPS Antenna and diplexer unit
The GPS antenna is installed at the rear of the roof on the centreline. A diplexer unit on the underside of the GPS
antenna amplifies the radio signals received from the GPS satellites and transmits them through separate dedicated
co-axial cable to the navigation computer for processing.

NAVIGATION SYSTEM
87-4 DESCRIPTION AND OPERATION

Inputs and Outputs
In addition to the vehicle sensor and the antenna inputs, the navigation computer also receives the following:
lA permanent battery feed from the passenger compartment fusebox, to power the navigation function.
lAn ignition switched battery feed from the passenger compartment fusebox, to power the navigation, radio and
CD functions when the ignition switch is in positions I and II.
lAn illumination power feed for switch illumination and LCD backlighting when the exterior lights are on.
Navigation computer outputs consist of those for the ICE system speakers and to the auxiliary CD autochanger, where
fitted.
Security Code
The navigation computer is programmed with a five digit security code selected from numbers 1 to 7. If the battery or
the navigation computer are disconnected, the code is requested on the LCD the first time the navigation computer
is switched on after reconnection; this also occurs if a different removable panel is fitted.
The code is entered using the appropriate multifunction buttons. The navigation computer automatically starts to
operate when the fifth digit of the correct code is entered. If an incorrect code is entered, CODE is displayed on the
LCD to prompt another entry attempt. If an incorrect code is entered three times in succession, WAIT is displayed on
the LCD and the unit is disabled for approximately 60 minutes. If the navigation computer is switched off, the
remaining disabled time will resume when the power is restored.
Automatic Volume Control (AVC)
The AVC feature automatically increases and decreases the audio volume with increases and decreases of vehicle
road speed. The AVC feature, also known as the GAL setting, uses the vehicle speed signal from the ABS ECU and
can be turned off or adjusted to start at a different vehicle speed. The GAL setting is accessed through the User Menu
and can be set to between 0 and +15, where 0 is off and +1 to +15 progressively increase the vehicle speed at which
AVC starts to operate.

INSTRUMENTS
DESCRIPTION AND OPERATION 88-1
INS TRUMENTS DESCRIPTION AND OPERAT ION
Instrument pack
1Hill descent control information warning lamp
2Overspeed warning lamp
3Brake system warning lamp
4Malfunction Indicator Lamp (MIL)
5Tachometer
6Direction indicator warning lamp
7Main beam warning lamp
8Direction indicator warning lamp
9Speedometer
10SRS warning lamp
11Off road mode warning lamp
12Glow plug warning lamp
13Trailer warning lamp
14Water in fuel filter warning lamp
15Transmission high temperature warning lamp
16Seat belt warning lamp17Fuel tank level gauge
18Low fuel level warning lamp
19LCD odometer/trip meter
20Anti-theft status warning lamp
21ABS warning lamp
22Gearbox manual/sport mode warning lamp
23Alternator charge warning lamp
24ACE warning lamp
25Oil pressure warning lamp
26SLS warning lamp
27Hill descent control warning lamp
28Engine coolant temperature gauge
29High coolant temperature warning lamp
30Traction control warning lamp
31Differential lock warning lamp
32Transfer box neutral warning lamp

INSTRUMENTS
DESCRIPTION AND OPERATION 88-3
Instrument component location -
Passenger compartment
LHD illustrated
1ACE ECU
2BCU
3ECM (V8 models)
4SLABS ECU5SRS DCU
6EAT ECU
7Instrument pack

INSTRUMENTS
88-4 DESCRIPTION AND OPERATION
Instrument block diagram
1Instrument pack
2ECM
3Brake fluid level switch
4Parking brake switch
5Oil pressure switch
6Alternator
7Fuel tank sender unit
8Water in fuel filter sensor
9Transmission temperature sensor
10Differential lock switch - vehicles up to 03
model year or Differential lock switches -
vehicles from 03 model year11Audible warning speaker
12SRS DCU
13SLABS ECU
14BCU
15ACE ECU
16EAT ECU
17Diagnostic connector
18Serial communications link

INSTRUMENTS
88-6 DESCRIPTION AND OPERATION
The third warning lamp pack is located in the top right-hand side of the instrument pack and contains the following
warning lamps:
lSRS warning lamp.
lSLS off road mode warning lamp.
lTrailer warning lamp.
lGlow plug warning lamp.
lWater in fuel filter warning lamp.
lSeat belt warning lamp.
lTransmission high temperature warning lamp.
The fourth warning lamp pack is located underneath the tachometer of the instrument pack contains the following
warning lamps:
lOil pressure warning lamp.
lAlternator charge warning lamp.
lHDC fault warning lamp.
lSelf Levelling Suspension (SLS) warning lamp.
lActive Cornering Enhancement (ACE) warning lamp.
lGearbox manual/sport mode warning lamps.
The serial communication link is used to allow information to travel to and from the instrument pack, and it provides
the ability to configure the instrument pack to a specific market. It also allows the instrument pack to be controlled by
TestBook for diagnostics.
There are five market specific variants of the instrument pack:
lUnited Kingdom (UK).
lNorth American Specification (NAS).
lCanada.
lAustralia.
lRest Of the World (ROW), Gulf and Japan.
The main difference between the five markets is that the speedometer will indicate road speed in mph as major figures
and km/h as minor figures, km/h as major figures and mph as minor figures or km/h only.
When TestBook is used to diagnose the instrument pack it demands each of the dials and warning lamps to operate
in-turn so a visual check of their operation can be made.
CAUTION: The instrument pack must not be stored on its face side at any time. This is because the dials have
damping fluid within them to ensure smooth operation of the dials' indicator needles. This fluid will leak out.
Speedometer
The speedometer informs the driver of the current vehicle road speed. It has a Liquid Crystal Display (LCD) to show
odometer, trip meter and, on automatic gearbox models, the selected gear. The speedometer will not show speeds
of less than 1.5 mph (2.5 km/h).
There are three different market configurations:
lNAS and UK = mph as major figures km/h as minor figures.
lCanada = km/h as major figures mph as minor figures.
lROW and Australia = km/h only.
The Self Levelling and Anti-Lock Brake System (SLABS) ECU provides the signal input for the road speed. The signal
is at 8000 pulses per mile (1.6 kilometres).

INSTRUMENTS
DESCRIPTION AND OPERATION 88-7
LCD odometer/trip meter
The LCD has 3 different display elements:
lOdometer.
lTrip meter.
lSelected gear (on vehicles with automatic gearboxes).
The odometer displays units in either miles or kilometres. It has a range from 0 to 999,999 units, only full units are
displayed irrespective of the type of units selected, the display will stop at 999,999 units. TestBook can be used to
reset the odometer. This is allowed only once and must be carried out before 150 miles (240 km) from new, after this
distance the feature is disabled. The odometer may lose up to one km (0.6 miles) when the battery is reconnected,
this is due to the software incorporated into the instrument pack to prevent anyone tampering with the odometer
reading.
The trip meter displays units in either miles or kilometres and has a range of 0.0 to 999.9 units. The display rolls over
from 999.9 to 0.0 units. Units down to one tenth of a mile or one tenth of a kilometre are displayed. The trip meter
displays 0.0 when the battery is reconnected or charged from a discharged state.
A push button located next to the LCD is utilised to reset the trip meter to zero and to change the units from miles to
kilometres. Pressing the button for less than 2 seconds allows the display to reset to zero. Pressing the button for
more than 2 seconds changes the units from miles to kilometres and vice versa. The units will only change for UK,
NAS and Canadian market vehicles.
The selected gear displays when the automatic gearbox is in park, reverse, neutral, drive 3,2,1, by using the letters
or numbers PRND321 in the display.
The data input for the LCD odometer/trip meter is from the SLABS ECU for the distance input and from the BCU for
the gear position. The instrument pack provides the earth path to illuminate the gear position warning lamp.
If a replacement instrument pack is required TestBook must be used to retrieve the odometer reading, so that when
the new instrument pack is fitted the odometer reading can be programmed in.

INSTRUMENTS
88-14 DESCRIPTION AND OPERATION
Overspeed warning lamp
The overspeed warning lamp within the instrument pack utilises an amber LED and a clear legend. The BCU
illuminates the LED when the vehicle speed has exceeded 77 mph (123 km/h) and remains on until the vehicle speed
falls below 74 mph (118 km/h), providing the driver with a visible warning. There is no self-check for this warning lamp.
There are two configurations for this warning lamp:
lGulf = symbol.
lAll other markets = disabled.
The instrument pack provides the power input and the warning lamp is controlled by the instrument pack according
to PWM signal received from the ECM. The road speed information is derived from the SLABS ECU.
The lamp activation thresholds are shown in the table below
Lamp on Lamp off
Input pulse, Hz 165.75 158.83
Road speed, mph (km/h) 77 (123) 74 (118.5)