Part 2

Electronic Engine Controls

Stop Lamp Switches









Both stop lamp switches are mounted adjacent to each other on the brake pedal bracket. The stop lamp switch is a normally open switch, the stop lamp diagnostic switch is normally closed to ground.
Both switches are connected directly to the CJB (central junction box). The stop lamp switch is also connected to the ECM (engine control module) for speed control functions.
Stop Lamp Diagnostic Switch
The stop lamp diagnostic switch opens a ground path to the CJB (central junction box) when the brake pedal is depressed. The ground path is used by the CJB (central junction box) to determine switch and brake pedal operation. The CJB (central junction box) can diagnose the operation of the stop lamp switch and the status of the switch can be read using a Land Rover approved diagnostic system.
Stop Lamp Switch
The stop lamp switch receives a permanent 12V fused supply from the CJB (central junction box) and when the brake pedal is depressed passes a signal voltage to both the CJB (central junction box) and the ECM (engine control module). The ECM (engine control module) can diagnose the operation of the stop lamp switch and the status of the switch can be read using a Land Rover approved diagnostic system.
The ABS (anti-lock brake system) module, the ECM (engine control module) and the CJB (central junction box) use the signals from both stop lamp switches and also the brake pressure sensor to perform plausibility checks. If one of the stop lamp switches fails, the diagnostic checks will be aware of the fault and the brake warning indicator in the instrument cluster will be illuminated.

Accelerator Pedal Position (APP) Sensor





The APP (accelerator pedal position) sensor is located on the accelerator pedal. The sensor comprises a plastic housing which contains two potentiometers and an analogue/digital converter. The potentiometers are connected to a common shaft which is actuated by movement of the accelerator pedal.
The APP (accelerator pedal position) sensor receives a fused 12V supply from the ignition relay in the CJB (central junction box). The sensor provides two outputs; the analogue output is transmitted directly to the CJB (central junction box), which in turn issues the signal to the ECM (engine control module) on the CAN (controller area network) bus, the second output is the PWM (pulse width modulation) signal which is transmitted directly to the ECM (engine control module). Both the analogue and PWM (pulse width modulation) signals transmit the same positional information.
The ECM (engine control module) uses the analogue sensor and the PWM (pulse width modulation) sensor information to calculate the required position of the throttle disc in the electric throttle body. The ECM (engine control module) then actuates the motor in the electric throttle assembly to move the throttle disc to the correct angle in relation to the pedal position.
In the event of a failure of the PWM (pulse width modulation) signal, the ECM (engine control module) uses the analogue signal received from the CJB (central junction box) as a replacement. If the analogue signal is also incorrect or missing, the ECM (engine control module) limits the maximum engine speed to 2000 rpm.
The PWM (pulse width modulation) and the analogue signal are used for diagnosing faults with the APP (accelerator pedal position) sensor. If the ECM (engine control module) detects a difference between the analogue and PWM (pulse width modulation) signals a fault code is stored. The ECM (engine control module) will use the signal with the lowest value for electric throttle control. The APP (accelerator pedal position) sensor position and any stored fault codes can be read using a Land Rover approved diagnostic system.

Turbocharger Wastegate Control Solenoid Valve





The wastegate control solenoid valve is attached to a bracket which is attached to the turbocharger compressor housing.
The solenoid valve is controlled by the ECM (engine control module) to control the turbocharger boost pressure using signals from the boost air pressure and temperature sensor. The ECM (engine control module) operates the valve using a 12V PWM (pulse width modulation) signal to modulate the air pressure supplied to the wastegate pressure actuator at a minimum of 20 Hz.
The wastegate control solenoid valve is a three-way valve with three hose connections; the first hose discharges excess pressurized air from the pressure actuator into the air inlet to the turbocharger, the second hose receives pressurized air from the compressor housing and the third hose supplies pressurized air to the wastegate pressure actuator. The valve connects the pressurized air from the compressor to either the pressure actuator or discharges the pressure into the turbocharger intake.
The ECM (engine control module) can monitor the solenoid valve operation and record DTC (diagnostic trouble code)'s. The solenoid valve has a resistance value of 23 Ohms ± 1.2 Ohms.

Turbocharger Boost Air Pressure and Temperature Sensor





The boost air pressure and temperature sensor is located in the outlet elbow of the charge air cooler. The sensor is sealed in the cooler with an O ring seal and secured with a single bolt.
The boost air pressure and temperature sensor is used by the ECM (engine control module) to monitor the boost pressure and temperature from the turbocharger. The ECM (engine control module) uses this information and information from other sensors to maintain the optimum boost pressure and modulate the pressure using the wastegate pressure control valve and pressure actuator.

Fuel Pump Driver Module (FPDM)
The FPDM (fuel pump driver module) is located in the LH (left-hand) rear of the luggage compartment. The module is attached to a bracket suspension turret and secured with two bolts.
The low pressure fuel pump (located in the fuel tank) operation is regulated by the FPDM (fuel pump driver module) which is controlled by a PWM (pulse width modulation) signal, output by the ECM (engine control module). The FPDM (fuel pump driver module) regulates the fuel flow and pressure output of the low pressure pump by controlling the fuel pump using a PWM (pulse width modulation) output
The FPDM (fuel pump driver module) is powered by a supply from the fuel pump relay in the BJB (battery junction box). The fuel pump relay is energized on opening the driver's door or when power mode 9 engine crank is initiated using the stop/start button. The FPDM (fuel pump driver module) supplies power to the fuel pump, and adjusts the power to control the speed of the fuel pump and thus the pressure and flow in the low pressure fuel delivery line.
For additional information, refer to Fuel Tank and Lines Fuel Tank and Lines

Low Pressure (LP) Fuel Sensor





The LP fuel sensor is located on a bracket on the top of the engine. It is located in a connector between the fuel supply pipe from the fuel tank pump module and the LP supply pipe to the High Pressure (HP) fuel pump. The sensor measures the fuel pressure being supplied from the tank mounted fuel pump module to the High Pressure (HP) fuel pump.
The LP fuel sensor is a peizo resistor type sensor. The sensor receives a 5V reference voltage supplied through a resistor within the ECM (engine control module) and produces an analogue signal of between 0 and 5V depending on the pressure sensed. Low pressure gives a low voltage output and consequently high pressure gives a higher voltage output. The ECM (engine control module) uses this pressure signal to adjust the fuel pump module output pressure by sending controlling signals to the FPDM (fuel pump driver module) and for injector timing.
The ECM (engine control module) monitors the LP fuel sensor for faults and can store fault related DTC (diagnostic trouble code)'s. These can be retrieved using a Land Rover approved diagnostic system.

Fuel Rail Pressure Sensor





The fuel rail pressure sensor is located on the fuel rail on the LH (left-hand) side of the engine. The sensor measures the fuel pressure in the fuel rail which is supplied from the HP fuel pump.
The fuel rail pressure sensor is a peizo resistor type sensor. The sensor receives a 5V reference voltage supplied through a resistor within the ECM (engine control module) and produces an analogue signal of between 0 and 5V depending on the pressure sensed. Low pressure gives a low voltage output and consequently high pressure gives a higher voltage output. The ECM (engine control module) uses this pressure signal to monitor the fuel pressure in the fuel rail and adjust the HP fuel pump fuel metering valve to control the fuel pressure in the fuel rail.
The ECM (engine control module) monitors the fuel rail 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.

Fuel Injectors





Four fuel injectors are located between the cylinder head and the fuel rail. The injectors are sealed in the cylinder head with O-ring seals and held in position by the fuel rail.
The ECM (engine control module) supplies the power and ground for each injector. The ECM (engine control module) operates the injectors by supplying power and ground signals to the solenoid valves in the injector. When the signals are applied the solenoid valve operates and the injector sprays pressurized fuel from the fuel rail directly into the cylinder. The amount of fuel injected and the timing of the injection period is controlled by the ECM (engine control module) using data from other sensors. The ECM (engine control module) can monitor the injector operation by monitoring both lines to the injector. Each injector can be diagnosed by the ECM (engine control module) and fault codes stored. The codes can be read using a Land Rover approved diagnostic system.
If a fuel injector fails, the engine will suffer from unstable idle speed, poor NVH (noise, vibration and harshness) and poor emissions performance. The engine MIL (malfunction indicator lamp) in the instrument cluster will also be illuminated.

Variable Camshaft Timing (VCT) Solenoid Valves





The VCT (variable camshaft timing) solenoids are located in the camshaft cover at the front of the engine. Each valve is sealed in the cover with O ring seals and secured with a bolt. Both solenoids are located in the front camshaft bearing cap which has internal drillings to direct pressurized oil to the VCT (variable camshaft timing) actuators.
The VCT (variable camshaft timing) solenoid comprises an electro-magnetic valve with a spring loaded piston. Slots in the piston allow oil to be channelled to the VCT (variable camshaft timing) actuator. The VCT (variable camshaft timing) actuators rotate the inlet and exhaust camshafts to adjust the camshaft timing as required. The direction in which the camshaft is rotated is dependent on the chamber in the VCT (variable camshaft timing) actuator which is supplied with oil pressure from the slot in the VCT (variable camshaft timing) solenoid piston.
An oil filter is located in the front camshaft bearing cap to prevent contaminants affecting the function of the solenoid valves.
Each VCT (variable camshaft timing) solenoid receives a fused battery supply via the BJB (battery junction box). Operation of the solenoid valves is controlled by the ECM (engine control module). The ECM (engine control module) provides a PWM (pulse width modulation) ground for the VCT (variable camshaft timing) solenoid. This allows oil to be directed to different chambers in the VCT (variable camshaft timing) actuators at variable rates, allowing the inlet and exhaust camshaft angle positions to be controlled independently and precisely.
Each solenoid valve operates on a 12V supply at 100A and has a resistance of 7.40 Ohm ± 0.50 Ohms. The ECM (engine control module) can diagnose the operation of the VCT (variable camshaft timing) solenoids and store fault related codes. The codes can be read using a Land Rover approved diagnostic system.

Purge Valve





The purge valve is located on the LH (left-hand) side of the engine, forward of the intake manifold. The valve is attached to a bracket which is secured to the FEAD (front end accessory drive) idler pulley bracket.
The purge valve is a solenoid operated valve which is closed when de-energized. The valve is controlled by the ECM (engine control module) and is operated when engine operating conditions are correct to allow vapor purging of the charcoal canister.
The purge valve receives a fused 12V battery supply via the BJB (battery junction box). The ECM (engine control module) provides a PWM (pulse width modulation) ground for the valve. The duty ratio of the PWM (pulse width modulation) ground determines the opening time of the purge valve.

Heated Oxygen (Lambda) Sensors





Two HO2S (heated oxygen sensor)'s are used by the ECM (engine control module) to measure the oxygen content of the exhaust gasses leaving the engine. One front (upstream) sensor measures the gasses before they pass through the catalytic converter and a second rear (downstream) HO2S (heated oxygen sensor) sensor measures the gasses after they have passed through the catalytic converter.
The HO2S (heated oxygen sensor) comprises a solid electrolyte Zirconium dioxide cell surrounded by a gas permeable ceramic coating. The output voltage from the sensor is dependent on the level of O passing through the permeable ceramic coating. Nominal voltage for lambda=1 is 300 to 500mV. As the fuel/air mixture becomes richer (lambda<1) the voltage rises to up to 900mV. As the mixture becomes weaker (lambda>1) the voltage falls towards 0mV.
Both HO2S (heated oxygen sensor)'s receive a 12V fused battery supply via the ECM (engine control module) relay in the BJB (battery junction box).
The HO2S (heated oxygen sensor) receive a fused 12V power supply from the ECM (engine control module) relay in the BJB (battery junction box). The front HO2S (heated oxygen sensor) is connected to the ECM (engine control module) on five wires and the rear HO2S (heated oxygen sensor) is connected to the ECM (engine control module) on three wires. The sensor connections provide power input, ground and analogue input and output to the ECM (engine control module).
Pre-Heating
The HO2S (heated oxygen sensor) operate efficiently at temperatures above 300°C (572°F). The normal operating temperature is between 300°C and 850 °C (572°F and 1562°F). In order to reach the optimum operating temperature quickly, the HO2S (heated oxygen sensor) is electrically pre-heated by the ECM (engine control module). Pre-heating the sensors also prevents condensation which can damage the sensor.
Each HO2S (heated oxygen sensor) contains a PTC (positive temperature coefficient) resistor which functions as the heating coil. The resistor is supplied with 12V current from the ECM (engine control module) relay in the BJB (battery junction box) and the ECM (engine control module) provides the ground for the resistor. When the sensor PTC (positive temperature coefficient) resistor coil is cold, resistance through the resistor will be low allowing a high current to pass, heating the coil. The ECM (engine control module) controls the current using a PWM (pulse width modulation) ground. As the resistor coil heats up, the resistance through the coil increases, reducing the current flow. The ECM (engine control module) reduces the duty cycle of the
PWM (pulse width modulation) ground until a continuous ground is provided. The ECM (engine control module) uses a PWM (pulse width modulation) ground to prevent damage to the sensor by thermal shock due to the sensor heating up too quickly
The PTC (positive temperature coefficient) resistor coil is heated following an engine start for approximately 20 seconds and also during low load conditions where the exhaust gas temperature is insufficient to maintain the optimum sensor temperature. The ECM (engine control module) can diagnose faults in the PTC (positive temperature coefficient) resistor and can record DTC (diagnostic trouble code)'s which can be retrieved using a Land Rover approved diagnostic system.
Front (Upstream) HO2S
The front HO2S (heated oxygen sensor) is located in the exhaust outlet pipe between the turbocharger and the catalytic converter.
The upstream HO2S (heated oxygen sensor) is used by the ECM (engine control module) to monitor the oxygen content of the exhaust gasses leaving the engine before they reach the catalytic converter. The ECM (engine control module) will check the output from the HO2S (heated oxygen sensor) to determine the combustion mixture and ensure lambda=1 is obtained. lambda=1 is the optimum air/fuel ratio which relates to a mixture of 14.7 kg air per 1 kg of fuel (14.7:1).
The HO2S (heated oxygen sensor) uses current regulation and outputs a linear signal dependent on the ratio of exhaust gas oxygen to ambient oxygen. The oxygen content of the exhaust gasses is measured by comparing it with ambient air drawn into the HO2S (heated oxygen sensor)
Rear (Downstream) HO2S
The rear HO2S (heated oxygen sensor) is located in the exhaust system between the catalytic converter and the flange connection for the center section exhaust. The rear HO2S (heated oxygen sensor) is used by the ECM (engine control module) to monitor the oxygen content of the exhaust gasses leaving the catalytic converter. The ECM (engine control module) can use this information to check (when the conditions for catalyst diagnostics have been met) for correct operation of the catalytic converter. The ECM (engine control module) uses the information from the rear HO2S (heated oxygen sensor) to enhance the signals from the front HO2S (heated oxygen sensor)
The rear HO2S (heated oxygen sensor) is similar in its construction to the front HO2S (heated oxygen sensor) with the exception of the output signal to the ECM (engine control module). The output signal is a binary signal where the amplitude of the signal curve changes considerably when the oxygen content in the exhaust gasses changes. The oxygen content of the exhaust gasses leaving the catalytic converter are measured by comparing it with ambient air drawn into the HO2S (heated oxygen sensor).

Ignition Coils





Four ignition coils are fitted directly to the spark plugs and are located in the center of the camshaft cover. The two inner coils for cylinders 2 and 3 are secured to the camshaft cover with screws and the two outer coils for cylinders 1 and 4 are secured with two studs and nuts.
The ignition coils are each connected to the ECM (engine control module) by a signal wire for the ECM (engine control module) to operate the coil. A second wire from the coil goes to a splice in the harness supplying the coil with a ground signal. The third connection on the coil is a fused 12V power supply from the ECM (engine control module) relay in the BJB (battery junction box).
Each coil contains a power stage which controls the primary current. The ECM (engine control module) controls the spark timing and production by switching the power stage of each coil to ground allowing the coil to charge up and then produce a spark at the spark plug at the appropriate time
The coil has a resistance of 0.730 Ohms - 0.08 Ohms + 0.07 Ohms.

Electric Throttle





The electric throttle is located at the entrance of the intake manifold and is secured to the manifold with four Torx head bolts.
The electric throttle comprises the throttle body, a round throttle disc which is actuated by a motor and a TP (throttle position) sensor. The electric throttle is controlled by the ECM (engine control module) which receives positional signals from the TP (throttle position) sensors. If a failure of the motor occurs, the throttle disc is returned to an emergency position by the springs, the throttle disc remains partially open with limited engine speed available to the driver.
The electric throttle has six wires which are connected to the ECM (engine control module). Two wires supply 12V current and ground for the DC motor. Four more wires go to the TP (throttle position) sensor. Two wires supply a 5V reference voltage and a ground to two analogue, Hall Effect sensors. Two further wires provide the TP (throttle position) sensor negative and positive signal feedback to the ECM (engine control module). As the throttle angle increases, the output of the negative sensor decreases and the output of the positive sensor increases


The motor is a DC (direct current) damper motor which drives a gear wheel and two springs; one for opening and one for closing. The motor rotates the spindle to which the throttle disc is attached. PWM (pulse width modulation) signals from the ECM (engine control module) control the motor to adjust the position of the throttle disc, regulating the amount of air entering the inlet manifold for combustion. Movement of the motor is achieved by changing the polarity of the power supply to the DC (direct current) motor, allowing it to be operated in both directions. The throttle disc and the motor has two maximum positions; throttle disc closed which allows minimal air flow through the electric throttle into the intake manifold and throttle disc open which allows maximum air flow into the intake manifold.
The ECM (engine control module) calculates the throttle disc position by comparing the feedback signals to stored values at a known datum position. The two signals are also compared to ensure that they show an accurate throttle disc position. The ECM (engine control module) performs a self test and a calibration routine on the throttle disc position at each ignition cycle. This is achieved by the ECM (engine control module) powering the damper motor to fully close the throttle disc and, if required, fully open the throttle disc.
The ECM (engine control module) monitors the DC (direct current) damper motor and the TP (throttle position) sensor for faults and can store fault related DTC (diagnostic trouble code)'s. These can be retrieved using a Land Rover approved diagnostic system.

Knock Sensors





The knock sensors are piezo-ceramic sensors that allow the ECM (engine control module) to employ active knock control and prevent engine damage from pre-ignition or detonation. Knocking or 'pinking' describes the combustion process in which flame speeds in the region of the speed of sound occur. This can happen towards the end of the combustion process if, after the normal combustion process has started, unburnt air/fuel mixture on the combustion chamber walls self ignites under increasing pressure. These pressure peaks can damage the pistons, cylinder head gasket and the cylinder head.
Two knock sensors are installed on the LH (left-hand) side of each cylinder block, below the intake manifold, one mid-way between cylinders 1 and 2, and one mid-way between cylinders 3 and 4. Each knock sensor is secured with a single screw. On each knock sensor, a two pin electrical connector provides the interface with the engine harness.
The ECM (engine control module) compares the signals from the knock sensors with mapped values stored in memory to determine when detonation occurs on individual cylinders. When detonation is detected, the ECM (engine control module) retards the ignition timing on that cylinder for a number of engine cycles, then gradually returns it to the original setting.
The ECM (engine control module) cancels closed loop control of the ignition system if the signal received from a knock sensor becomes implausible. In these circumstances the ECM (engine control module) defaults to base mapping for the ignition timing. This ensures the engine will not become damaged if low quality fuel is used. The MIL (malfunction indicator lamp) will not illuminate, although the driver may notice that the engine 'pinks' in some driving conditions and displays a drop in performance and smoothness. The ECM (engine control module) calculates the default value if one sensor fails on each bank of cylinders.