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Lotus Service Notes Section EMN
Page 6
test. Run a further test to verify the repair.
Prog
The 'programme' menu is available only on the MEMS 2J card, and allows matching of the engine
management and security 5AS modules if one or the other is replaced. At the instant of ignition is switch on,
the security 5AS module sends a unique coded signal to the engine management ECM, which must be recog-
nised by the ECM before it will allow the engine to run. If no code, or an incorrect code is received, the ECM
will prevent fuelling of the engine, although the engine may crank - typically resulting in engine start followed
immediately by a stall. If either the engine ECM or security 5AS module is replaced, or swopped from another
vehicle, the ECM must be taught to recognise the coded 5AS signal by selecting 'MEMS MATCHING' from the
'PROG' menu and following the instructions.
When mems matching is complete, it is then necessary to select 'CALIBRATION ID' from the 'PROG'
menu to complete the operation - Unless this is performed, the engine will not run.
Note that for standard cars, ECM matching can only be carried out using the '5AS' card and security
password system - refer to service notes sub-section MN.2.
Test
This programme is more comprehensive than the Pre-Test, and takes about 10 minutes to complete tests
on many of the engine management components. During this routine, the scanner display will ask a series of
questions and issue instructions to guide the operator through the test, some parts of which require that the
engine be run up to normal operating temperature. The test should be used any time that a driveability concern
is reported, or if the Pre-Test does not identify the problem.
Components tested in this routine include:
- Coolant temperature sensor;
- Fuel injectors;
- Fuel pump;
- Oxygen sensor heater relay;
- Purge valve solenoid;
- VCC control solenoids (note that it is not normally possible to hear these solenoids operate);
- Throttle position sensor;
- Cooling fan;
- Tachometer;
- Idle air control motor;
- Oxygen sensor;
The test results should be printed out to identify any detected faults. If a fault is recorded, note that
problem may be in the component or the associated circuitry. Refer to the appropriate EMN sub-section or
circuit diagram to diagnose the fault. Displaying 'Live Data' (see below) may also help diagnosis.
Live Data
This programme, which requires the ignition to be switched on, allows readings from various sensors to
be displayed with or without the engine running. This facility may also be used to observe the sensor readings
whilst the car is being driven, which may help to identify an intermittent problem. Requesting a print, will freeze
the data at that instant and print out a complete list. Comparison of data with a known good car may help to
identify a problem. Erroneous readings may be due to a faulty sensor, or its associated circuitry; refer to the
appropriate EMN sub-section or circuit diagram.
Engine parameters monitored include:
- Engine rpm;
- Manifold vacuum;
- IAC valve position;
- Throttle position sensor reading;
- Coolant temperature;
- Inlet air temperature;
- Oxygen sensor voltage.
Tune
The 'test' programme is available only on the MEMS 2J card, and allows the oxygen sensor circuit to be
tested and the IAC valve to be tested and reset without performing a full 'test' programme.