Part 3

Electronic Engine Controls

Stop Lamp Switch





The stop lamp switch is attached to the brake pedal bracket, adjacent to the speed control inhibit switch. When the brake pedal is pressed, a plate on the pedal moves away from the switch plunger allowing the plunger to extend and complete the switch contacts.
The switch receives a permanent, fused battery voltage via the BJB and the CJB. The switch is connected to the ECM which provides the ground path. The ground (battery voltage signal) is used by the ECM as a switch operation signal. The ground from the switch is routed via the CJB to the ECM which allows the CJB to also determine the switch operation.
The CJB uses the completed ground when the switch is operated to activate the stop lamps.
The ECM 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.

Ambient Air Temperature (AAT) Sensor





The AAT sensor is located in the underside of the Left Hand (LH) exterior door mirror. The sensor is a Negative Temperature Co-efficient (NTC) thermistor element. The element resistance decreases as the sensor temperature increases which produces a low signal voltage. The ECM supplies the sensor with a 5V reference voltage and a ground and measures the returned signal voltage as an outside temperature.
The AAT signal is used by the ECM for a number of functions including engine cooling fan control and A/C compressor displacement control. The ECM also transmits a message on the high speed CAN bus relating to the current outside temperature for use by other control modules.
The ECM can diagnose the operation of the AAT sensor and the sensor output values can be read using a Land Rover approved diagnostic system.

Fuel Pump Driver Module (FPDM)





The FPDM is located in the LH rear corner of the luggage compartment, behind the trim panel and is secured to the LH chassis longitudinal with 2 screws.
The FPDM receives a battery supply via the fuel pump relay in the CJB. The relay is energized by the CJB when a request is received from the ECM. Two wires connect the FPDM to the fuel pump motor and a ground is via a body ground point. The ECM is connected to the FPDM on a single wire and this is used to control the pump pressure output and consequently the pump output pressure. The ECM uses signals from the MAP sensor, the fuel rail pressure/temperature sensor and the MAF/IAT sensor to determine and control the pump output.
The ECM outputs a PWM signal to the FPDM. The frequency of the signal determines the duty cycle of the FPDM which subsequently controls the pump pressure output. The frequency of the PWM signal represents half of the 'on' time of the pump. If the ECM outputs a PWM signal of 50% on time, the FPDM will operate the pump at 100% (permanently on). If the ECM outputs a PWM signal of 5%, the FPDM will operate the pump at 10% on time. The FPDM will only operate the fuel pump if it receives a PWM signal from the ECM of between 4% and 50%. If the ECM requires the pump to be stopped, the ECM transmits a PWM signal at a cycle of 75%.
If the power supply to the FPDM from the CJB or the fuel pump relay is disrupted for any reason, the fuel pump will not operate. The FPDM is monitored by the ECM for faults. Faults with the FPDM are stored in the ECM as fault codes which can be retrieved using a Land Rover approved diagnostic system.

Variable Camshaft Timing (VCT) Solenoid





The VCT solenoid is located in the LH end of the cylinder head and is secured with a bolt. The VCT solenoid is a valve which controls the oil flow to the VCT unit.
The VCT solenoid receives a fused battery supply via the main relay. The ECM provides a pulsed ground for the solenoid.
The VCT solenoid comprises an electro-magnetic valve with a spring loaded piston. Slots in the piston allows oil to be channelled to the VCT unit. The VCT unit rotates the inlet camshaft to adjust the camshaft timing as required. The direction in which the camshaft is rotated is dependent on the chamber in the VCT unit which is supplied with oil pressure from the slot in the VCT solenoid piston. For additional information, refer to Engine - 3.2L
An oil filter is located in the intake channel for the VCT solenoid to prevent contaminants affecting the function of the valve.
Operation of the valve is controlled by the ECM. The ECM provides a PWM ground for the VCT solenoid. This allows oil to be directed to different chambers in the VCT unit at variable rates, allowing the camshaft angle position to be controlled smoothly and precisely.
The ECM can diagnose the operation of the VCT solenoid and store fault related codes. The codes can be read using a Land Rover approved diagnostic system.

Camshaft Profile Switching (CPS) Solenoid - Front/Rear





Two CPS solenoids are located at each end of the cylinder head, adjacent to the inlet camshaft and are each secured with a bolt. The CPS solenoids supply oil pressure to the hydraulic tappet locking pins allowing the camshaft profile to be changed. Each solenoid controls the oil pressure supply to the hydraulic tappet locking pins on 3 cylinders. For additional information, refer to Engine - 3.2L
The CPS solenoids receive a fused battery supply via the main relay. The ECM provides a ground for the solenoid, which actuates a valve within the solenoid allowing oil pressure to adjust the camshaft profile.
The ECM can diagnose the operation of the CPS solenoids and store fault related codes. The codes can be read using a Land Rover approved diagnostic system.

Ignition Coils





Six plug top coils are used on the i6 engine and are located in recesses in the top of the cylinder head. The coils are controlled by the ECM and receive a fused, battery voltage supply via the main relay. The ECM controls the spark timing and production by switching the primary circuit of each coil to ground allowing the charge which has built up in the coil to produce a spark at the spark plug.
Each coil contains a power stage which controls the primary current and the ECM sends a signal to each coil to operate the power stage switching at the appropriate time. Each coil has a feedback wire to the ECM which allows the ECM to diagnose each individual coil and store fault related codes. The codes can be read using a Land Rover approved diagnostic system.
A suppressor is mounted on the camshaft cover adjacent to ignition coil 3 to prevent interference from the coils and/or the injectors affecting audio operation.

Fuel Injectors





Six fuel injectors are used on the i6 engine and are located on the inlet side of the cylinder head. The injectors are sealed in the cylinder head with O-ring seals and held in position by the fuel rail.
The injectors receive a fused battery voltage supply via the main relay. The ECM operates the injectors by grounding solenoid valves in the injector. When the ground is applied the solenoid valve operates and the injector sprays pressurized fuel from the fuel rail into the cylinder intake ports. The amount of fuel injected and the timing of the injection period is controlled by the ECM using data from other sensors.
The ECM can monitor the injector operation by monitoring the ground line from the injector. Each injector can be diagnosed by the ECM and fault codes stored. The codes can be read using a Land Rover approved diagnostic system.

Variable Intake System (VIS)
The VIS changes the length of the inlet manifold using two ECM controlled actuators which move flaps to control the air flow. The actuators operate singularly or together to adjust the length of the inlet tract.
Using an 'H' bridge, the intake and plenum actuator's internal electronics changes the actuator motor's polarity and therefore the flap position. At each flap position change, the DC actuator motor is powered for approximately 0.5 seconds. The worm gear design ensures that the flap remains in the desired position, even when the electric motors are not powered.

Intake Tract Variable Manifold





The ECM controls the position of the flaps by modulating the relevant actuator's control signal. If the signal shifts from low (approximately 1 volt) to high (approximately 10 volts) the internal electronics interpret it as the flap must close. If the signal shifts from high to low, the flap must open.
At engine speeds of less than 3800 rpm both the intake and plenum flaps are closed. At engine speeds of approximately 3800 rpm and higher the intake flap begins to open, effectively shortening the length of the intake manifold. At engine speeds of 4800 rpm or higher both the intake and plenum flaps are open, providing the shortest length of intake manifold.





Plenum Variable Intake Manifold





The ECM diagnoses via the actuator if the flap has assumed the correct position. It does this, by comparing the desired air flow with the actual air flow. A fault code is stored if the deviations are outside the tolerances. The codes can be read using a Land Rover approved diagnostic system.
If an actuator fails and the flap is in the open position, it is not possible to remove the actuator and flap assembly from the inlet manifold. A small indentation on the body of the actuator allows for a 3 mm Allen key to be pushed through the thin membrane wall of the actuator housing. The Allen key can be engaged in the spindle of the actuator motor which allows the flap to be turned to the closed position and consequently the actuator and flap assembly can then be removed from the intake manifold.

Purge Valve





The purge valve is located on a bracket on the inlet manifold, above the electric throttle. The valve has a hose connection on the bottom which connects into the electric throttle and allows the fuel vapors to be drawn into the inlet manifold. A larger connection on the side of the valve is connected via a pipe to the evaporative (EVAP) emission canister which is located in the LH wheel arch behind the liner.
The purge valve controls the flow of fuel vapor from the EVAP canister to the engine intake manifold. Vacuum in the intake manifold draws the vapor from the canister once the purge valve is open and burns the vapor as part of the combustion process.
The ECM controls the operation of the purge valve when engine operating conditions are correct to add the fuel vapor to the combustion process. The valve is an electro-magnetic solenoid valve which receives a fused battery voltage supply via the main relay. The ECM uses a PWM ground to control the operation of the valve. By altering the frequency of the PWM ground signal, the ECM can control the rate at which valve is open. This allows the ECM to precisely control the amount of fuel vapor passing from the EVAP canister. For additional information, refer to Evaporative Emissions Description and Operation
The ECM can diagnose faults with the purge valve and store fault related codes. The codes can be read using a Land Rover approved diagnostic system.

Fuel Tank Leakage Monitoring Module (NAS only)





The fuel tank leakage monitoring module is located in the LH rear wheel arch, adjacent to the EVAP canister. A port on the side of the module provides for the attachment of a dust filter, through which fresh air is drawn into the EVAP canister. A port on the underside of the module is connected by a short curved hose to the EVAP canister. This connection allows fresh air to be drawn into the canister during the purge process and also allows the system to be pressurized by the module for leakage testing.
The fuel tank leakage monitoring module receives a fused battery voltage supply via the main relay. The module is connected to the ECM which provides a ground for the module when leak detection is required.
The fuel tank leakage monitoring module comprises an electric air pump, a solenoid valve and a heater element. The air pump is used to pressurize the EVAP system for leak testing. The solenoid valve is normally open, but closes when energized by the ECM to close the system to allow it to be pressurized. The PTC heater element is used to warm the pump before operation.
The fuel tank leakage monitoring system periodically checks the EVAP system and the fuel tank vent system for leaks when the ignition is off. The system can also be activated for a diagnostic check by the ECM.
The ECM checks for leaks in the system by operating the air pump in the fuel tank leakage monitoring module. The module air pump is activated and the ECM monitors the current draw on the air pump motor. A reference orifice is provided in the module which allows the ECM to make a comparison and establish a reference figure for measuring the current draw on the air pump motor when air is pumped through the orifice. For additional information, refer to Evaporative Emissions Description and Operation
The ECM can diagnose faults with the air pump and the solenoid valve and store fault related codes. These codes can be read using a Land Rover approved diagnostic system.

Speed Control Inhibit Switch





The speed control inhibit switch is attached to the brake pedal bracket, adjacent to the stop lamp switch. When the brake pedal is pressed, a plate on the pedal moves away from the switch plunger allowing the plunger to extend and complete the switch contacts.
The switch receives a power supply from the CJB which senses the completed ground path when the switch is operated. The switch has two functions; it is used for starting purposes when the brake pedal must be pressed before engine cranking is allowed and it is used to suspend speed control operation when speed control is active and the brake pedal is pressed.
The CJB can diagnose the operation of the speed control inhibit switch and the status of the switch can read using a Land Rover approved diagnostic system.

Main Relay
The main relay is located in the BJB. The operation of the main relay is controlled by the ECM which provides a ground path for the main relay coil, energizing the relay and closing the relay contacts.
The main relay supplies battery voltage to the following engine sensors and actuators:
- Electric throttle - TP sensor (via ECM)
- Fuel injectors
- Ignition coils
- Coil Capacitor
- Variable inlet cam profile switching solenoid - front and rear
- Intake tract variable manifold motor
- Plenum variable intake manifold motor
- HO2S
- Purge valve
- Fuel tank leakage monitoring pump (NAS only).

Air Conditioning (A/C) Pressure Sensor
The refrigerant pressure sensor provides the Air Temperature Control (ATC) module with a pressure input from the high pressure side of the refrigerant system. The refrigerant pressure sensor is hardwired to the ECM, which uses the signal to control operation of the A/C compressor and to calculate the additional load on the engine when the A/C compressor is operating.
The ECM also broadcasts the refrigerant high pressure value over the high speed Controller Area Network (CAN) bus to the CJB. The CJB relays the signal to the ATC module over the medium speed CAN bus to increase the amount of recirculated air if required.