Part 3

Electronic Engine Controls

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.

Air Conditioning (A/C) Relay
The A/C relay is located in the BJB. The operation of the A/C relay is controlled by the ECM which provides a ground path for the A/C relay coil, energizing the relay and closing the relay contacts.
When the relay contacts are closed, battery voltage is supplied via the relay to the A/C compressor clutch. The ECM controls the operation of the variable displacement compressor using a signal line to the compressor and received signals from the A/C pressure sensor.

Air Conditioning Compressor Control
Compressor displacement is controlled by the ECM based on current evaporator temperature and target evaporator temperature signals received from the ATC module. From these values the ECM calculates the required compressor displacement and provides a Pulse Width Modulated (PWM) signal to the compressor solenoid valve. The compressor solenoid valve is mounted on the rear of the compressor and interprets the PWM signal as a displacement value and alters the position of the internal swash plate accordingly.
The ECM will also reduce the displacement of the A/C compressor to its minimum level if 'full throttle' or automatic transmission 'kick down' is requested. This feature is not present on Gulf specification vehicles. Compressor clutch engagement is controlled by the ECM.

Engine Cooling Fan Control
The ECM has a hardwired connection with the cooling fan control module. The ECM outputs a PWM signal to the fan control module which relates to the required fan speed. The fan speed is determined by factors such as engine coolant temperature and A/C operation. The fan control module reacts to the received signal by controlling the operating voltage of the fan motors. The fan control module confirms the fan speed operation on the same connection back to the ECM.

Starter Motor Relay
The starter motor relay is located in the BJB. The operation of the starter motor relay is controlled by the ECM which provides a ground path for the relay coil, energizing the relay and closing the relay contacts. When the relay contacts are closed, battery voltage is supplied, via the starter motor relay, to the starter module solenoid coil. The starter solenoid is energized and connects the starter motor with a direct battery feed to operate the starter motor.
Once the engine has started, the ECM removes the starter motor relay ground, opening the relay contacts and terminating the battery feed to the starter solenoid, which in turn stops the operation of the starter motor. For additional information, refer to Starting System - 3.2L Description and Operation

Fuel Pump Module
The fuel pump is controlled by the FPDM which in turn is controlled by the ECM. The FPDM provides positive and negative feeds to the fuel pump motor which is controlled with a PWM output. The fuel pump is run for 2 seconds to prime the fuel system once ignition on is sensed by the ECM.For additional information, refer to Fuel Tank and Lines Fuel Tank and Lines

Malfunction Indicator Lamp (MIL)
The MIL is located in the instrument cluster and is illuminated by a CAN message from the ECM when an emission related fault occurs. The ECM also illuminates the MIL when requested to do so by the TCM and to perform a bulb check when the ignition is switched on. There is no MIL illumination for non emission related engine management faults. All engine faults are recorded with a Diagnostic Trouble Code (DTC) which can be retrieved using a Land Rover approved diagnostic system. For additional information, refer to Electronic Engine Controls - 3.2L Testing and Inspection

Generator Feedback Signal
The generator has a Local Interconnect Network (LIN) bus connection direct to the ECM. The LIN bus is used by the ECM to request voltage for battery charging and to monitor the fault status of the generator.