1999 LAND ROVER DISCOVERY transmission

DRIVING AIDS
DESCRIPTION AND OPERATION 86-8-11
Operation
PDC System Operation
When the ignition switch is in position II and reverse gear is selected, the PDC sensors are automatically activated.
The PDC ECU only activates the system if reverse is selected for more than 1 second. This avoids nuisance audible
warnings when the gear selector lever is being moved between Drive and Park on vehicles with automatic
transmission.
When the system is activated, the PDC ECU illuminates the indicator LED in the PDC switch, switches on the
ultrasonic sensors and generates a single chime on the PDC sounder to indicate the system is active. If an object is
range of the sensors when the system is activated, a series of audible warnings are emitted by the PDC sounder
immediately.
If PDC operation is not required, it can be suspended temporarily by pressing the PDC switch. When reverse is
deselected and subsequently reselected, PDC will automatically become active again.
PDC can also be manually selected when not in reverse gear by pressing the PDC switch. A second press of the
switch is required to turn off the PDC or the PDC will be deactivated if reverse is selected and then deselected.
Sensor Operation
The PDC ECU processes the distance readings from the ultrasonic sensors to determine if there are any objects
within the detection areas. If there are no objects in the detection areas, there are no further audible warnings. If an
object is detected, repeated audible warnings are produced on the PDC sounder.
The maximum detection range is 1800 mm (70 in). When an object is detected, the time delay between the audible
warning tones decreases as the distance between the detected object and the vehicle decreases until, at
approximately 450 mm (17 in), the audible warning tone is continuous.
After the initial detection of an object, if there is no decrease in the distance between an object and the central sensors,
the time delay between the audible warnings remains constant. If an object is detected by one of the corner sensors
only, the audible warnings stop after about 5 seconds if there is no change in the distance between the object and the
corner sensor.

DRIVING AIDS
86-8-12 DESCRIPTION AND OPERATION
Park Distance Control Detection Areas
aIntermittent Warning Tone
bContinuous Warning Tone
Detection Calculation
When operating in the combined transmitter and receiver mode, the sensor outputs a number ultrasonic pulses and
receives the reflected echo signal. The ECU amplifies the received echo signals and compares them with a
preprogrammed threshold to calculate the distance to the object. This is achieved by determining the elapsed time
between the transmission and reception of the ultrasonic signal.
When operating in receiver mode, the sensor receives echo signals transmitted by an adjacent sensor. This mode is
used to improve the accuracy of the system.
The detection cycle consists of the ECU operating one sensor in the combined transmitter and receiver mode and
transmitting a number of ultrasonic pulses. The ECU then switches the transmitting sensor and the adjacent sensor(s)
to receiver mode. After a short time delay, this sequence is repeated using a different sensor to transmit the ultrasonic
pulse and continues until all four sensors have output an ultrasonic signal. This sequence is completed in 100ms. The
ECU uses several measurements of the same sensors to remove errors from the calculation.
If the object is directly behind a sensor, the distance is calculated using the time between the transmission and
reception of the signal. If the object is positioned between two sensors, the ECU uses both signals to determine the
correct distance using triangulation.
To perform the triangulation calculation, the ECU must know the distance between the individual sensors in the
bumper. This information is stored in the ECU memory. From the received distance from each sensor and using the
known distance between adjacent sensors, the ECU can calculate the minimum distance from the vehicle to the
object.
When approaching several objects, the ECU recognises the distance from the vehicle to the nearest object.
A
Y- Y
1800mm (70in)
450mm (17in)
600mm (23.5in)
YY
B
M86 5917

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
88-2 DESCRIPTION AND OPERATION
Instrument component location - Engine
compartment / underneath vehicle
1ECM (diesel models)
2Alternator
3Glow plugs
4Transmission temperature sensor
5Water in fuel filter sensor
6Fuel tank sender unit
7Differential lock switch – vehicles up to 03
model year8Differential lock switches – vehicles from 03
model year (where fitted)
9Parking brake switch
10Brake fluid level switch
11Oil pressure switch

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
88-32 DESCRIPTION AND OPERATION
Transmission high temperature warning lamp
The transmission high temperature warning lamp within the instrument pack utilises a red LED and a clear legend.
On vehicles fitted with automatic gearboxes, the transmission high temperature warning lamp is utilised to provide the
driver with a visible warning that the automatic gearbox oil has exceeded a normal operating temperature. The
warning lamp will extinguish if the gearbox oil returns back to normal operating temperature.
When the ignition is switched on, the instrument pack illuminates the LED to provide a self-check, providing there is
no fault it will remain illuminated for 3 seconds or until the ignition is switched off.
The power input for the LED is supplied by the instrument pack via fuse 13. The temperature sensor provides the
earth path to illuminate the transmission high temperature warning lamp.
The transmission high temperature warning lamp is controlled according to the voltage present on the temperature
sensor to instrument panel earth path:
l< 1.8 volts = warning lamp on.
l> 7.7 volts = warning lamp off.

INSTRUMENTS
88-38 DESCRIPTION AND OPERATION
Gearbox manual/sport mode warning lamps
The gearbox manual/sport mode warning lamps within the instrument pack each utilise a green LED and a clear
legend. On vehicles fitted with an automatic gearbox, operating the manual mode switch instructs the Electronic
Automatic Transmission (EAT) ECU to illuminate the manual mode LED. Operating the sport mode switch instructs
the EAT ECU to illuminate the sport mode LED.
There is no self-test performed at ignition on for this warning lamp.
If the EAT ECU detects a fault it will cause both warning lamps to flash.
The power input for the LED's is supplied by the instrument pack. The EAT ECU applies a high or low voltage to the
instrument pack microprocessor which measures the applied voltage from the ECU and illuminates the appropriate
warning lamp.
The voltage on the earth paths from the EAT ECU to the instrument pack has the following functions:
Warning lamp response Manual earth path, volts Sport earth path, volts
No lamps > 7.7 > 7.7
Sport warning > 7.7 < 1.8
Manual warning < 1.8 > 7.7
Both lamps flash < 1.8 < 1.8