Part 1
Electronic Engine Controls
NOTE:
A = Hardwired; D = High Speed CAN Bus; O = Local Interconnect Network (LIN) Bus
CONTROL DIAGRAM - SHEET 1 OF 2
CONTROL DIAGRAM - SHEET 2 OF 2
OPERATION
The ECM (engine control module) processes inputs from the following sources:
- BJB (battery junction box)
- Generator
- CJB (central junction box)
- ECT (engine coolant temperature) sensor 1
- ECT (engine coolant temperature) sensor 2 (NAS only)
- Immobilizer Antenna Unit (IAU)
- TCM (transmission control module)
- APP (accelerator pedal position) sensor
- Ambient temperature sensor
- LP fuel sensor
- Oil pressure sensor
- CMP (camshaft position) sensor (inlet)
- CMP (camshaft position) sensor (exhaust)
- CKP (crankshaft position) sensor
- A/C (air conditioning) pressure sensor
- Front HO2S (heated oxygen sensor)
- Rear HO2S (heated oxygen sensor)
- Oil temperature sensor
- Fuel rail pressure sensor
- Turbocharger boost pressure and temperature sensor
- MAP (manifold absolute pressure) sensor
- MAF (mass air flow)
- Knock sensors (2 off)
- Stop lamp diagnostic switch
- Stop lamp switch
- RCM (restraints control module)
- A/C (air conditioning) compressor clutch
- Electric throttle position sensors.
The ECM (engine control module) outputs controlling signals to the following sensors and actuators:
- FPDM (fuel pump driver module)
- Cooling fan control module
- Fuel injectors
- Fuel pump metering valve
- Turbocharger wastegate control solenoid
- VCT (variable camshaft timing) solenoid (inlet)
- VCT (variable camshaft timing) solenoid (exhaust)
- Purge valve
- Ignition coils (4 off)
- Electric throttle motor
- DMTL pump (NAS only).
The ECM (engine control module) is connected to the engine sensors which allow it to monitor the engine operating conditions. The ECM (engine control module) processes these signals and decides the actions necessary to maintain optimum engine performance in terms of driveability, fuel efficiency and exhaust emissions. The memory of the ECM (engine control module) is programmed with instructions for how to control the engine, this known as the strategy. The memory also contains data in the form of maps which the ECM (engine control module) uses as a basis for fueling and emission control. By comparing the information from the sensors to the data in the maps, the ECM (engine control module) is able to calculate the various output requirements.
The ECM (engine control module) contains an adaptive strategy which updates the system when components vary due to production tolerances or ageing. Some sensors receive a regulated 5 Volt supply from the ECM.
The ECM (engine control module) receives a vehicle speed signal on a CAN (controller area network) bus from the ABS (anti-lock brake system) module. Vehicle speed is an important input to the ECM (engine control module) strategies. The ABS (anti-lock brake system) derives the speed signal from the ABS (anti-lock brake system) wheel speed sensors. The frequency of this signal changes according to road speed. The ECM (engine control module) uses this signal to determine the following:
- How much to reduce engine torque during gear changes
- When to permit speed control operation
- To control the operation of the speed control system
- Implementation of the idle strategy when the vehicle is stationary.
Ignition is controlled by a direct ignition system, provided by 4 plug top coils. The ECM (engine control module) is able to detect and correct for ignition knock on each cylinder and adjust the ignition timing for each cylinder to achieve optimum performance.
The ECM (engine control module) controls operation of the starter motor via the starter relay in the BJB (battery junction box). The ECM (engine control module) also protects the starter motor, preventing operation of the starter relay if the engine speed signal exceeds a predetermined value
The ECM (engine control module) and the CJB (central junction box) exchange encrypted data to validate and approve an engine start. For additional information, refer to Anti-Theft - Passive Description
DESCRIPTION
Engine Control Module (ECM)
The ECM (engine control module) is located at the rear of the engine compartment, between the bulkhead and the engine sound insulation. The ECM (engine control module) is located in a plastic molded carrier which in turn is located in a bracket attached to the vehicle structure.
The ECM (engine control module) is connected to the vehicle harnesses via 2 connectors. The ECM (engine control module) contains data processors and memory microchips. The output signals to the actuators are in the form of ground paths provided by driver circuits within the ECM (engine control module). Some output signals take the form of high side drive signals. The ECM (engine control module) driver circuits produce heat during normal operation and dissipate this heat via the ribbed casing.
The ECM (engine control module) performs self diagnostic routines and stores fault codes in its memory. These fault codes and diagnostics can be accessed using a Land Rover approved diagnostic system.
If the ECM (engine control module) is to be replaced, the new ECM (engine control module) is supplied 'blank' and must be configured to the vehicle using a Land Rover approved diagnostic system. A 'flash' EEPROM (electrically erasable programmable read only memory) allows the ECM (engine control module) to be externally configured, using a Land Rover approved diagnostic system, with market specific or new tune. The current engine tune data can be accessed and read using a Land Rover approved diagnostic system. When a new ECM (engine control module) is fitted, it must also be synchronized to the CJB (central junction box) using a Land Rover approved diagnostic system. ECM (engine control module)'s cannot be 'swapped' between vehicles.
Camshaft Position (CMP) Sensors
Two CMP (camshaft position) sensors are used; one for the inlet camshaft and one for exhaust camshaft. The sensors are located on the top of the camshaft cover and are each sealed with an O ring seal and secured with a bolt to the cover.
The sensors are Hall effect sensors which read off a target on each camshaft. Each sensor receives a 5V reference voltage from the ECM (engine control module). Two further connections to the ECM (engine control module) provide ground and signal output. The ECM (engine control module) uses the signals from the CMP (camshaft position) sensors and the CKP (crankshaft position) sensor to determine current camshaft position and camshaft adjustment.
If a fault occurs with one or both CMP (camshaft position) sensors, a DTC (diagnostic trouble code) is registered in the ECM (engine control module). Two types of failure can occur; camshaft signal frequency too high or total failure of the camshaft signal. The DTC (diagnostic trouble code) recorded by the ECM (engine control module) can also relate to a total failure of the crankshaft signal or crankshaft signal dynamically implausible. Both components should be checked to determine the cause of the fault.
If a fault occurs with a CMP (camshaft position) sensor when the engine is running, the engine will continue to run. Once the engine is switched off, the engine will crank and restart while the fault is present, but VCT (variable camshaft timing) control will be disabled.
Crankshaft Position (CKP) Sensor
The CKP (crankshaft position) sensor is located at the front of the engine, adjacent to the crankshaft pulley/vibration damper. The sensor is secured to two bosses on the engine front cover and secured with two bolts. The sensor receives a 5V reference voltage from the ECM (engine control module). Two further connections to the ECM (engine control module) provide ground and signal output.
The CKP (crankshaft position) sensor is positioned adjacent to the trigger wheel, which is an integral part of the crankshaft pulley/vibration damper. The trigger wheel has 58 teeth and a section where 2 teeth are missing. The sensor is a Hall effect sensor which uses the missing teeth on the trigger wheel to determine the crankshaft position and rotational speed.
If a fault occurs with the CKP (crankshaft position) sensor, a DTC (diagnostic trouble code) is registered in the ECM (engine control module). If the sensor fails when the engine is running the engine will stall and will not restart until the fault has been corrected.
The ECM (engine control module) uses the signal from the CKP (crankshaft position) sensor for the following functions:
- Synchronization
- Determine fuel injection timing
- Produce an engine speed signal which is broadcast on the CAN (controller area network) bus for use by other systems.
Mass Air Flow (MAF) Sensor
The MAF (mass air flow) sensor is located on the top cover of the air filter box and is secured with two screws. The sensor is downstream of the air filter and measures the air entering the clean air duct to the turbocharger.
The MAF (mass air flow) sensor receives a 12V power supply from the BJB (battery junction box). Three further connections provide signal feedback to the ECM (engine control module) for intake air temperature and air volume.
The MAF (mass air flow) sensor works on the hot film principle. Two sensing elements are contained within a film. One element is maintained at ambient (air intake) temperature, e.g. 25°Celsius (77°F). The other element is heated to 200°Celsius (392°F) above the ambient temperature, e.g. 225°Celsius (437°F). Intake air entering the engine passes through the MAF (mass air flow) sensor and has a cooling effect on the film. The ECM (engine control module) monitors the current required to maintain the 200°Celsius (392°F) differential between the two elements and uses the differential to provide a precise, non-linear, frequency based signal which equates to the volume of air being drawn into the engine.
The MAF (mass air flow) sensor output is a digital signal related to the mass of the incoming air. The ECM (engine control module) uses this data, in conjunction with signals from other sensors and information from stored fueling maps, to determine the precise fuel quantity to be injected into the cylinders.
The ECM (engine control module) checks the calculated air mass against the engine speed. If the calculated air mass is not plausible, the ECM (engine control module) uses a default air mass figure which is derived from the average engine speed compared to a stored characteristic map. The air mass value will be corrected using values for boost pressure, atmospheric pressure and air temperature.
If the MAF (mass air flow) sensor fails the ECM (engine control module) implements the default strategy based on engine speed. In the event of a MAF (mass air flow) sensor signal failure, any of the following symptoms may be observed:
- Difficult starting
- Engine stalls after starting
- Delayed engine response
- Emission control inoperative
- Idle speed control inoperative
- Reduced engine performance.
Mass Air Pressure (MAP) Sensor
A single MAP (manifold absolute pressure) sensor is located in the intake manifold and is secured with two screws. The sensor provides a voltage signal to the ECM (engine control module) relative to the intake manifold pressure.
The MAP (manifold absolute pressure) sensor has a three pin connector which is connected to the ECM (engine control module) and provides a 5V reference voltage from the ECM (engine control module), a signal input to the ECM (engine control module) and a ground connection.
The MAP (manifold absolute pressure) sensor uses a diaphragm transducer to measure the air pressure which allows the ECM (engine control module) to detect quick pressure changes in the intake manifold after the electric throttle. The signal is used in conjunction with the MAF (mass air flow) sensor signal to calculate the injection period
The ECM (engine control module) monitors the engine MAP (manifold absolute pressure) sensor for faults and can store fault related DTC (diagnostic trouble code)'s. These can be retrieved using a Land Rover approved diagnostic system. If the sensor fails, the ECM (engine control module) uses the MAF (mass air flow) sensor signal value as a substitute.
Engine Coolant Temperature (ECT) Sensor(s)
On vehicles in all markets an ECT (engine coolant temperature) sensor 1 is located in the water outlet on the cylinder head.
On NAS market vehicles an additional ECT (engine coolant temperature) sensor 2 is used which is mounted in a 'Y' piece in the radiator bottom return hose. This sensor measures the radiator outlet temperature.
The ECT (engine coolant temperature) sensor 1 provides the ECM (engine control module) and the instrument cluster with engine coolant temperature status. The additional ECT (engine coolant temperature) sensor 2 used on NAS vehicles enables the ECM (engine control module) to monitor the operation of the thermostat.
The ECM (engine control module) uses the temperature information for the following functions:
- Fueling calculations
- Limit engine operation if engine coolant temperature becomes too high
- Cooling fan operation.
The instrument cluster uses the temperature information for temperature gauge operation. The engine coolant temperature signal is transmitted on the CAN (controller area network) bus by the ECM (engine control module) for use by the instrument cluster and other systems.
The ECT (engine coolant temperature) sensor circuit consists of a voltage divider which incorporates the NTC (negative temperature coefficient) thermistor within the ECT (engine coolant temperature) sensor. The input to the sensor is a 5V reference voltage supplied through a resistor within the ECM (engine control module). The ground from the sensor is also connected to the ECM (engine control module) which measures the voltage across the sensor. As the coolant temperature rises the resistance of the sensor decreases and vice versa. The output voltage from the sensor changes as the thermistor allows more current to pass to ground relative to the temperature of the coolant. The ECM (engine control module) calculates the coolant temperature from a map of sensor voltage against temperature.
The ECM (engine control module) adjusts fuel delivery for the measured coolant temperature to ensure optimum driveability at all times. The engine will require more fuel when it is cold to overcome fuel condensing on the cold metal surfaces inside the combustion chamber. To achieve a richer air/fuel ratio, the ECM (engine control module) extends the injector opening time. As the engine warms up the air/fuel ratio is leaned off.
If the ECT (engine coolant temperature) sensor fails, the following symptoms may be observed:
- Difficult cold starting
- Difficult hot starting
- Reduced engine performance
- Temperature gage inoperative or inaccurate reading.
In the event of ECT (engine coolant temperature) sensor signal failure, the ECM (engine control module) applies a default value of 80°Celsius (176°F) coolant temperature for fueling purposes.
Engine Oil Pressure Sensor
The oil pressure sensor is located in a threaded port in the oil filter adaptor. The sensor contacts are closed and ground an input from the ECM (engine control module) when insufficient oil pressure is present or the engine is not running. The sensor contacts are open at a minimum engine oil pressure of 0.15 to 0.41 bar (2.2 to 5.9 Psi).
The oil pressure sensor is connected directly to the ECM (engine control module). The ECM (engine control module) outputs the engine oil pressure state on the high speed CAN (controller area network) bus for use by the instrument cluster. This message informs the instrument cluster if the switch is open or closed. The instrument cluster then turns the warning light on or off accordingly.
Engine Oil Temperature Sensor
The engine oil temperature sensor is located in a hole in the LH (left-hand) side of the oil pan. The sensor is sealed to the oil pan with an O ring seal and secured with flange head bolt.
The sensor uses an NTC (negative temperature coefficient) sensor to determine the oil temperature. The temperature sensor is a NTC (negative temperature coefficient) type which operates in the -40 Degrees Celsius to +159 Degrees Celsius temperature range. The sensor receives a 5V reference voltage supplied through a resistor within the ECM (engine control module) and returns a voltage to the ECM (engine control module) relative to the oil temperature and resistance through the NTC (negative temperature coefficient) sensor.
Fuel Pump Metering Valve
The fuel metering valve is integral with the HP fuel pump, which is located on the rear of the cylinder head. The fuel metering valve returns unwanted fuel back to the Low Pressure (LP) system to be recycled back to the HP fuel pump.
The fuel metering valve receives a 10.8V PWM (pulse width modulation) power supply and a ground from the ECM (engine control module) to control the valve opening. The valve coil has a resistance of 0.49 Ohms ± 0.023.