1999 LAND ROVER DISCOVERY fuel

ENGINE MANAGEMENT SYSTEM - V8
18-2-8 DESCRIPTION AND OPERATION
Engine Control Module (ECM)
The engine control module (ECM) is located on the RH side A post below the face panel inside the vehicle. It has a
cast aluminium case and is mounted on a bracket. The ECM has 5 independent connectors totalling 134 pins.
The ECM is available in 4 variants:
lNAS.
lNAS low emission vehicles.
lUK/ Europe/ Japan/ Australia.
lROW/ Gulf.
The ECM uses a 'flash' electronic erasable programmable read only memory (EEPROM). This enables the ECM to
be externally configured, to ensure that the ECM can be updated with any new information, this also allows the ECM
to be configured with market specific data. TestBook must be used to configure replacement ECM's. The ECM can
be reprogrammed, using TestBook/T4, with new engine tunes up to 16 times to meet changing specifications and
legislation. The current engine tune data can be accessed and read using TestBook/T4.
The ECM memorises the positions of the crankshaft and the camshaft when the engine has stopped via the CKP and
CMP sensors. This allows immediate sequential fuel injection and ignition timing during cranking. This information is
lost if battery voltage is too low (i.e. flat battery). So the facility will be disabled for the first engine start.
Input/Output
The ECM has various sensors fitted to the engine to allow it to monitor engine condition. The ECM processes these
signals and decides what actions to carry out to maintain optimum engine operation by comparing the information
from these signals to mapped data within its memory.
Connector 1 (C0634): This connector contains 9 pins and is used primarily for ECM power input and earth. The ECM
requires a permanent battery supply, if this permanent feed is lost i.e. the battery discharges or is disconnected the
ECM will lose its adapted values and its Diagnostic Trouble Codes (DTC). These adapted values are a vital part of
the engine management's rolling adaptive strategy. Without an adaptive strategy, driveability, performance, emission
control, and fuel consumption are adversely affected. The ECM can be damaged by high voltage inputs, so care must
be taken when removing and replacing the ECM.

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-9
Pin out details connector C0634
Connector 2 (C0635): This connector contains 24 pins and is primarily used for Heated Oxygen Sensors (HO
2S)
control and earth. The HO
2S sensors require a heater circuit to assist in heating the tip of the sensors to enable closed
loop fuelling to be implemented quickly after cold starting.
Pin out details connector C0635
Pin No. Function Signal type Reading
1 Ignition position II Input 12 V
2 Not used - -
3 Not used - -
4 Chassis earth Earth 0V
5 Fuel injectors earth Earth 0V
6 Power stage earth Earth 0V
7 Permanent battery supply Input battery supply 12V
8 Switched relay positive Input switched 0-12V
9 Not used - -
Pin No. Function Signal type Reading
1HO
2S heater RH bank - downstream Output PWM 12-0V
2 Not used - -
3 Not used - -
4 Not used - -
5 Thermostat monitoring sensor Earth 0V
6 Not used - -
7HO
2S heater LH bank - downstream Output PWM 12-0V
8HO
2S sensor RH bank - downstream Earth/ Signal 0V
9HO
2S sensor LH bank - upstream Earth/ Signal 0V
10 HO
2S sensor RH bank - upstream Earth/ Signal 0V
11 HO
2S sensor LH bank - downstream Earth/ Signal 0V
12 Not used - -
13 HO
2S heater RH bank - upstream Output PWM 12-0V
14 HO
2S sensor RH bank - downstream Input/ Signal Analogue 0-5V
15 HO
2S sensor LH bank - upstream Input/ Signal Analogue 0-5V
16 HO
2S sensor RH bank - upstream Input/ Signal Analogue 0-5V
17 HO
2S sensor LH bank - downstream Input/ Signal Analogue 0-5V
18 Fuel pump relay Output Switch to earth
19 HO
2S heater LH bank - upstream Output PWM 12-0V
20 Not used - -
21 Thermostat monitoring sensor Signal Analogue 0-5V
22 Not used - -
23 Main relay Output Switch to earth
24 EVAP system leak detection pump motor (NAS
vehicles with positive pressure type, EVAP system
leak detection capability only)Output Switch to earth

ENGINE MANAGEMENT SYSTEM - V8
18-2-10 DESCRIPTION AND OPERATION
Connector 3 (C0636): This connector contains 52 pins and is used for most sensor and actuator inputs and outputs.
Sensor and actuator control is vital to ensure that the ECM maintains adaptive strategy
Pin out details connector C0636
Pin No. Function Signal type Reading
1 Injector cylinder number 2 Output Switch to earth
2 Injector cylinder number 5 Output Switch to earth
3 Purge valve Output, signal PWM 12-0V
4 SAI vacuum solenoid valve (NAS vehicles from 2000MY
only)Output Switch to earth
5 Not used - -
6 Fuel tank pressure sensor (NAS vehicles with vacuum type,
EVAP system leak detection only)Earth 0V
7 MAF sensor 5V supply Output, reference 5V
8 Not used - -
9 MAF sensor earth Earth 0V
10 TP sensor 5V supply Output, reference 5V
11 Not used - -
12 Not used - -
13 Not used - -
14 Injector cylinder number 7 Output Switch to earth
15 Injector cylinder number 6 Output Switch to earth
16 SAI pump relay (NAS vehicles from 2000MY only) Output Switch to earth
17 CMP sensor Earth 0V
18 Low range switch (manual transmission only) Input, signal Active low
19 Not used - -
20 CMP signal Input, signal Digital switch 0-12V
21 ECT sensor Earth 0V
22 Coolant temperature signal Input, signal Analogue 0-5V
23 MAF sensor signal Input, signal Analogue 0-5V
24 TP sensor signal Input, signal Analogue 0-5V
25 TP sensor earth Earth 0V
26 Not used - -
27 Injector cylinder number 3 Output Switch to earth
28 Injector cylinder number 8 Output Switch to earth
29 Hill decent control output Output, signal PWM 0-12V
30 EVAP canister vent solenoid (CVS) valve (NAS vehicles with
vacuum type, EVAP system leak detection only)Output Switch to earth
30 Leak detection pump solenoid (NAS vehicles with positive
pressure type, EVAP system leak detection only)Output Switch to earth
31 A/C condenser fan Output Switch to earth
32 CKP sensor signal Input, signal Analogue, 0-300V peak
33 Not used - -
34 IAT sensor signal Input, signal Analogue 0-5V
35 KS, RH bank earth Earth 0V
36 KS, RH bank signal Input, signal Analogue
37 Not used - -
38 Not used - -
39 Not used - -
40 Injector cylinder number 4 Output Switch to earth
41 Injector cylinder number 1 Output Switch to earth
42 Idle air control valve open Output, signal PWM 12-0V
43 Idle air control valve close Output, signal PWM 12-0V
44 ECT sensor signal Output, signal PWM 0-12V

ENGINE MANAGEMENT SYSTEM - V8
18-2-12 DESCRIPTION AND OPERATION
Connector 4 (C0637): This connector contains 40 pins and facilitates use of TestBook via the Diagnostic connector.
Also contained in this connector is the Malfunction Indicator Lamp (MIL), this instrument panel lamp informs the driver
of concerns within the engine management system.
Pin out details connector C0637
Pin No. Function Signal type Reading
1 Not used - -
2 Not used - -
3 Not used - -
4 Not used - -
5 Not used - -
6 Not used - -
7 Not used - -
8 Low fuel level Input, signal Active high
9 Fuel tank pressure sensor (NAS vehicles with
vacuum type, EVAP system leak detection
capability only)Output, reference 5V
10 Not used - -
11 Not used - -
12 Analogue fuel level (NAS vehicles with positive
pressure type, EVAP system leak detection only)Input, signal 0-5V
13 Not used - -
14 Fuel tank pressure sensor (NAS vehicles with
vacuum type, EVAP system leak detection
capability only)Input, signal Analogue 0-5V
15 Not used - -
16 ATC compressor request Input, signal Active low
17 Engine speed output Output, signal PWM 0-5V
18 Not used - -
19 Not used - -
20 Malfunction indicator lamp 'ON' Output Switched earth
21 Not used - -
22 Vehicle speed signal (VSS) Input, signal PWM 0-12V
23 Not used - -
24 Not used - -
25 Not used - -
26 Not used - -
27 Not used - -
28 Not used - -
29 ATC compressor relay Output Switched earth
30 Not used - -
31 Positive pressure type EVAP system heater (02MY
vehicles only)Output, drive Switched earth
32 Diagnostic connector K-line Bi-directional Serial 0-12V
33 Immobiliser serial W link Input, signal Serial 0-12V
34 Rough road signal Input, signal PWM 0-12V
35 Not used - -
36 CAN data bus 'high line' Bi-directional 5-2.5V
37 CAN data bus 'low line' Bi-directional 0-2.5V
38 ATC stand by Input, signal Active low
39 Not used - -
40 Not used - -

ENGINE MANAGEMENT SYSTEM - V8
18-2-14 DESCRIPTION AND OPERATION
Crankshaft speed and Position (CKP) sensor (C0168)
The CKP sensor is located towards the rear of the engine below cylinder number 7, with its tip adjacent to the outer
circumference of the flywheel. The CKP sensor is the most important sensor on the vehicle and without its signal the
engine will not run. The signal produced by the CKP sensor allows the ECM to determine crankshaft angle and speed
of rotation. The ECM uses this information to calculate ignition timing and fuel injection timing.
The CKP sensor works as a variable reluctance sensor. It uses an electromagnet and a reluctor ring to generate a
signal. As the reluctor ring passes the tip of the CKP sensor the magnetic field produced by the sensor is cut and then
re-instated. The ECM measures the signal as an ac voltage.
The output voltage varies in proportion to engine speed. The reluctor ring has a set tooth pattern, 60 teeth are spaced
at 6° intervals and are 3° wide, two teeth are removed to provide a reference mark at 60° BTDC for number 1 cylinder.
There is no back up strategy or limp home facility if this sensor fails, the engine does not run.
Input/Output
Because of the nature of its operation the CKP sensor does not require any electrical input source. The CKP sensor
is a 3 pin variable reluctance sensor generating its own electrical output. The 2 output sources from the sensor are
earthed via pin 46 of connector C0636 of the ECM and sensor output is via pin 32 of connector C0636 of the ECM.
This output is in the form of an ac voltage waveform. The 3rd pin is used by the ECM as an earth screen, this screen
protects the integrity of the CKP sensor signal to ensure that outside electrical interference is eliminated, it is
controlled via pin 45 of connector C0636 of the ECM. The ac voltage generated from the CKP sensor is relative to
engine speed.

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-17
Camshaft Position (CMP) sensor (C0176)
The CMP sensor is located on the front of the engine, above and behind the crankshaft pulley. The CMP sensor is a
Hall effect sensor producing four pulses for every two crankshaft revolutions. The sensor is positioned close to the
camshaft gear wheel, the gear wheel has four slots machined at 90° intervals. This allows the ECM to recognise 4
individual cylinders every camshaft revolution or all 8 cylinders every crankshaft revolution.
The CMP sensor Hall effect works as a magnetic switch. It switches battery voltage on or off depending on the position
of the camshaft gear wheel in relationship to the sensor.
The ECM uses this signal for cylinder recognition to control sequential fuel injection, engine knock and diagnostic
purposes.
Input/Output
Electrical input to the camshaft position sensor is from fuse 2 located in engine compartment fuse box. One output is
sensor earth, the other is the signal output to the ECM via pin 20 of connector C0636.
The CMP sensor can fail the following ways or supply incorrect signal:
lSensor open circuit.
lShort circuit to vehicle battery supply.
lShort circuit to vehicle earth.
lIncorrect fitting of the sensor.
lExcessive camshaft gear wheel tolerance.
lExcessive camshaft endfloat.
lCamshaft and crankshaft misalignment.
lSpeed signal correlation with CKP sensor signal.
lCam wheel magnetised / residual magnetism
In the event of a CMP sensor signal failure any of the following symptoms may be observed:
lIgnition timing reverts to default values from ECM memory.
lLoss of cylinder correction.
lLoss of active knock control.
lLoss of active knock control diagnostics.
lLoss of cylinder identification for misfire diagnostics.
lLoss of quick synchronisation of crankshaft and camshaft for cranking/ start up.
lFuel injection could be 360° out of phase.
lFront HO
2S sensor ageing period diagnostic disabled (NAS only)
Should a malfunction of the component occur the following fault code may be evident and can be retrieved by
TestBook:
The fault condition has to be detected for more than 100 cam pulses (25 revolutions) when the engine speed is greater
than 500 rev/min.
P code J2012 description Land Rover description
P0340 Camshaft position sensor circuit malfunction Open/short circuit to vehicle supply or earth

ENGINE MANAGEMENT SYSTEM - V8
18-2-18 DESCRIPTION AND OPERATION
Engine Coolant Temperature (ECT) sensor (C0196)
The ECT sensor is located at the front of the engine adjacent to the coolant outlet pipe. The ECT sensor forms a vital
part of the ECM operating strategy, and therefore the optimum control of the running of the engine. Richer air/ fuel
ratio is required at lower coolant temperatures such as cold starting. Coolant temperature information from the ECT
sensor is also vital to enable the ECM to weaken the air/ fuel mixture as temperature rises to maintain low emissions
and optimum performance.
For NAS vehicles with secondary air injection, the signal from the ECT sensor is monitored at engine start, to
determine whether the conditions are cold enough to warrant secondary air injection to be employed. The ECT sensor
is then monitored to switch off the secondary air injection when the required engine coolant temperature has been
attained.

+ EMISSION CONTROL - V8, DESCRIPTION AND OPERATION, Secondary Air Injection System.
The ECT works as a Negative Temperature Coefficient (NTC) sensor. As temperature rises, the resistance in the
sensor decreases, as temperature decreases, the resistance in the sensor increases. The ECT sensor forms part of
a voltage divider chain with a pull up resistor within the ECM. Consequently as the ECT sensor resistance changes,
the analogue voltage at the input signal from the ECT sensor to the ECM will be adjusted which corresponds to the
temperature of the engine coolant. With this information, the ECM can implement the correct strategies for cold start,
warm up etc. The ECM supplies the instrument cluster with a pulse width modulated (PWM) coolant temperature
signal to drive the temperature gauge.

ENGINE MANAGEMENT SYSTEM - V8
18-2-22 DESCRIPTION AND OPERATION
Input/Output
The ECM provides the thermostat monitoring sensor with a 5 volt reference via pin 21 of connector C0635 of the ECM,
and an earth via pin 5 of connector C0635 of the ECM.
There are three types of thermostat monitoring sensor diagnostic checks:
lSensor signal is above maximum threshold. For the ECM to register this as a fault, and illuminate the MIL, the
temperature registered by the thermostat monitoring sensor must be above 140 °C (284 °F) for more than 1
second.
lSensor signal is below minimum threshold. For the ECM to register this as a fault, and illuminate the MIL, the
temperature registered by the thermostat monitoring sensor must be below -33 °C (-27 °F) for more than 1
second, while the inlet air temperature reading is greater than -32 °C (-25 °F).
lSignal difference between ECT sensor and thermostat monitoring sensor is below maximum threshold. For the
ECM to register this as a fault, and illuminate the MIL, the following conditions must exist:
lNo maximum or minimum threshold signal faults exist.
lNo faults are recorded against the thermostat monitoring sensor or vehicle speed signal.
lEngine not in idle speed control.
lFuel cut-off not active.
lEngine speed is greater than 400 rpm.
lRoad speed is greater than 0 mph.
lIntegrated mass air flow from engine start to fuel cut-off is greater than set value (between 3 kg and 10 kg
dependent upon engine coolant temperature at engine start).
lEngine coolant temperature at engine start is between 9 °C and 39 °C (48 °F and 102 °F).
lHigh range is selected.
lDelay time before thermostat monitoring is enabled is between set limits (between 50 and 500 seconds
dependent upon engine coolant temperature at engine start).
lEngine coolant temperature is greater than 90 °C (194 °F).
lThe difference between the ECT sensor reading and the thermostat monitoring sensor reading is less than
39 °C (102 °F).