EVAP Management Components Descriptions
Engine Control Module (ECM) - (up to 99MY)
The engine control module (ECM) prior to 99MY is a GEMS (Generic Engine Management System), it is located in a plastic moulded box behind the battery in the engine compartment.
The ECM has various sensors fitted to the engine to allow it to monitor engine condition The ECM processes these signals and decides what actions to carry out to maintain driveability, after comparing the information from these signals to mapped data within its memory.
Input/Output:
The black plastic case which houses the ECM protects it from sources of contamination including heat. The ECM itself is contained in a cast aluminium case. The ECM has 3 independent connectors totalling 90 pins, of which up to 66 are used, dependent on market variations.
18-pin black connector (C509):
This connector is used primarily for ECM power and earth connections.
NOTE: Voltages and other measurements given are approximations only. Actual values will depend on particular specification and will be effected by accuracy and calibration of the measurement tool used and impedances caused by harness wiring etc.
ECM Pin Details For Connector C509::
36-pin red connector (C507):
This connector is used primarily for sensor inputs to the ECM.
NOTE: Voltages and other measurements given are approximations only. Actual values will depend on particular specification and will be effected by accuracy and calibration of the measurement tool used and impedances caused by harness wiring etc.
ECM Pin Details For Connector C507::
ECM Pin Details For Connector C507 Continued::
36-pin black connector (C505):
This connector is used primarily for outputs to actuators and sensors driven by the ECM.
NOTE: Voltages and other measurements given are approximations only. Actual values will depend on particular specification and will be effected by accuracy and calibration of the measurement tool used and impedances caused by harness wiring etc.
ECM Pin Details For Connector C505::
ECM Pin Details For Connector C505 Continued::
Advanced Evaporative Emissions System - 98MY to 99MY (NAS only)
The Advanced evaporative emissions system is included on NAS vehicles from 98MY in compliance with OBD strategies. The system has the capability of detecting holes in the fuel system down to 1 mm (0.04 in.). The leak tests are performed by the ECM, allowing the tank to be depressurised and measuring the pressure over a period of time.
See EMISSION CONTROL, Description and operation. Description and Operation
Fault codes:
- P1440 - Purge valve stuck open.
- P0442 - Evaporative loss control system - small leak
- P0448 - Evaporative loss control system - major leak
- P0496 - Evaporative loss control system - major leak
- P0446 - Purge canister closure valve information
- P1447 - Purge canister closure valve - poor performance
Fuel Tank Pressure Sensor
This sensor is used on NAS vehicles with advanced evaporative emissions systems. The sensor is located in the fuel tank sender unit and is not a serviceable item. The GEMS ECM checks for any fuel system leaks through joints and holes, by measuring the pressure drop after the vent seal valve is shut. The diagnostic system performs out of range and validity checks.
The following failure modes are possible:
- Connector or harness open circuit
- Sensor earthing problem
- Blocked sensor
Certain failure modes may cause the 5V supply voltage which is shared with the throttle position sensor to be reduced to less than 1V.
Fault codes:
- P0451 - Fuel tank pressure sensor poor performance fault
- P0452 - Fuel tank pressure sensor low range fault
- P0453 - Fuel tank pressure sensor high range fault
See EMISSION CONTROL, Description and operation. Description and Operation
EVAP Canister Purge Valve
The purge valve is controlled by the GEMS ECM and allows hydrocarbons stored in the EVAP canister to be purged to the engine inlet manifold for burning. Electrical circuit integrity and system flow checks are performed.
If a purge valve breaks or becomes stuck, the purge system will cease to function, and there is no default operation measures. GEMS will store the fault if the correct monitoring conditions have been achieved (45 seconds after 15 minutes running). If a valve is stuck open, the engine may misfire and the fuelling adoptions will change.
The following failure modes are possible:
- Sticking valve
- Valve blocked
- Connector or harness wiring fault (open or short circuit)
- Valve stuck open
Fault codes:
- P0441 - Purge valve flow fault
- P0443 - Purge valve open or short circuit
See EMISSION CONTROL, Description and operation. Description and Operation
EVAP Canister Vent Solenoid (CVS) Valve
The CVS unit is located at the left hand side of the engine bay. The vent seal valve is normally open. When the GEMS ECM is required to run a fuel system test, the vent valve is closed to seal the system. The ECM is then able to measure the pressure in the fuel system using the fuel tank pressure sensor. Electrical integrity checks are performed on the CVS valve and a valve blockage can be determined from a depressurising fuel tank.
The following failure modes are possible:
- Connector or harness wiring fault (open or short circuit)
- Valve stuck open or shut
- Valve blocked
See EMISSION CONTROL, Description and operation. Description and Operation
Inertia Fuel Shut-off (IFS) Switch
The inertia switch isolates the power supply to the fuel pump in the event of sudden deceleration, as encountered during an accident. The inertia switch is located in the right hand side footwell behind an access flap. It is reset by depressing the central plunger at the top of the switch.