Fuel Tank Level Sensor

Cooling Fan Operation - Vehicles With A/C The engine cooling fan and the condensor fan are operated in parallel by the ECM via a cooling fan ECU. The cooling fan ECU, which is located behind the radiator below the bonnet closing panel, receives a Pulse Width Modulated (PWM) signal from the ECM. The frequency of the PWM signal, which is varied by the ECM, is used by the cooling fan ECU to determine the output voltage supplied to the fan motors.

Fan operation is also dependent on vehicle road speed. The ECM will adjust the required fan speed in relation to the road speed using CAN signals received from the ABS ECU.

The ECM varies the duty cycle of the PWM signal between 10% and 90%. At duty cycles of between 10% and 49% the cooling fan ECU will not supply any power to the fan motors. At a duty cycle of 50%, the ECU supplies 6 volts to the fan motors to operate them at a minimum speed of approximately 1300 rev/min. As the duty cycle increases above 50%, the ECU increases the voltage, non-linearly, to the fan motors up to 90%. At this point the fan motors are supplied with 12 volts and operate at a maximum speed of approximately 3000 rev/min.

When the main relay is energised, the cooling fan ECU requires a PWM signal from the ECM of between 10% and 90% duty cycle. If this condition is not detected, the ECU will assume a fault condition (open or short circuit) exists and operate the fans continuously at full speed when the main relay is energised to ensure that engine and A/C system do not overheat.

The ECM will operate the fans in response to inputs from the ECT sensor and the A/C switch and A/C pressure sensor. Refer to A/C system for details AIR CONDITIONING, DESCRIPTION AND OPERATION, Description.

When the engine is switched off, the ECM maintains the cooling fans in an active condition for up to 8 minutes. If the temperature does not reach a predetermined value within 4 minutes, the ECM will terminate the active period. If the fans are active and the temperature falls below a predetermined value, the ECM will terminate further fan operation.

Fuel Tank Level Sensor

The ECM receives a fuel tank level signal on the CAN bus from the fuel tank level sensor via the instrument pack and the ABS ECU. This signal is stored in a misfire freeze frame by the ECM for OBD misfire detection when the fuel tank level falls to below 15% of maximum capacity.

Malfunction Indicator Lamp (MIL)

The MIL is located in the instrument pack to inform the driver that there is fault with an emission critical part of the engine management system. When the ignition is switched to position II, the MIL is illuminated until the engine starts to check bulb function.

If a fault occurs on an emission related component, the ECM provides a CAN message to the instrument pack, via the ABS ECU, to operate the MIL LED.

Tachometer Drive

The tachometer drive is a CAN message output from the ECM to the instrument pack, via the ABS modulator.

Vehicle Immobilisation

The vehicle immobilisation system operates by the EWS3D immobilisation ECU transmitting a unique code to the ECM when the ignition is switched on. If the code is recognised by the ECM it will energise the injectors and allow the engine to start.

If no code is received or the code is incorrect, the ECM will disable the vehicle by not energising the fuel injectors.

The immobilisation ECU also controls the starter relay and will passively disarm the starter relay when the key is removed from the ignition switch. Rearming is performed by switching the ignition on, which activates a coil around the ignition key barrel.

The coil transmits a waveform signal which excites the remote handset to transmit a re-mobilisation signal. When the signal is received by the anti-theft alarm ECU, the starter relay will be enabled.