Doosan D20G, Service Manual

Page: 749 / 1209

G424F(FE) Service Manual Chapter 9. Advanced Diagnostics 249
Fault Action Descriptions
Each fault detected by the SECM is stored in
memory (FIFO) and has a specific action or result
that takes place. Listed below are the descriptions of
each fault action.
Engine Shutdown: The most severe action is an
Engine Shutdown. The MIL will light and the engine
will immediately shutdown, stopping spark, closing
the fuel lock-off closing, and turning off the fuel
pump and fuel injectors.
Delayed Engine Shutdown: Some faults, such as
low oil pressure, will cause the MIL to illuminate for
30 seconds and then shut down the engine.
Cut Throttle: The throttle moves to its default
position. The engine will run at idle but will not
accelerate.
Cut Fuel: Fuel flow will be turned off.
Turn on MIL : The MIL will light by an active low
signal provided by the SECM, indicating a fault
condition. May illuminate with no other action or may
be combined with other actions, depending on which
fault is active.
Soft Rev Limit / Medium Rev Limit / Hard Rev
Limit:
System will follow various sequences to bring
engine speed back to acceptable levels.
Level4 Power Limit / Level3 Power Limit / Level2
Power Limit / Level1 Power Limit:
The maximum
engine power output will be limited to one of four
possible levels. The engine power is calculated from
measured engine parameters (e.g. MAP, rpm, fuel
flow, etc).
Disable Gas O2 Control : In LPG mode, closed loop
correction of air fuel ratio based on the Pre-catalyst
O2 sensor is disabled.
Disable Liquid O2 Control: In Gasoline mode,
closed loop correction of air fuel ratio based on the
Pre-catalyst O2 sensor is disabled.
Fault List Definitions
All the analog sensors in the MI-07 system have
input sensor range faults. These are the coolant
temperature sensor, fuel temperature sensor,
throttle position sensors, pedal position sensors,
manifold pressure sensor, HEGO sensors, and
intake air temperature sensor. Signals to these
sensors are converted into digital counts by the
SECM. A low/high range sensor fault is normally set
when the converted digital counts reach the
minimum of 0 or the maximum of 1024 (1024 = 5.0
Vdc with ~ 204 counts per volt).
Additionally, the SECM includes software to learn
the actual range of the pedal position and throttle
position sensors in order to take full advantage of
the sensor range. Faults are set if the learned
values are outside of the normal expected range of
the sensor (e.g. APP1AdaptLoMin).