Doosan D35C-5 FDA04 Operation & Maintenance Manual page 153

Operation Section
Malfunction Indicator Lamp (MIL) Operation
How does my MIL work?
The emissions control system utilizes a MIL to warn the operator or technician of a possible issue with the
engine or emissions control system. The system will keep the MIL illuminated for the entire key cycle in
which the trouble code was set. It will keep the MIL illuminated for three additional engine run cycles under
the following two circumstances: (1) The fault caused the engine to shut down or (2) the fault is related to the
exhaust gas oxygen (EGO) sensors. This function is called MIL persistence.
How does MIL persistence work?
In the event the DTC is related to either an engine shutdown fault OR an oxygen sensor fault the following
statement applies: If the vehicle is not serviced by a technician and the condition causing the MIL
illumination (DTC) no longer exists, the MIL will remain illuminated for the 3 additional start cycles. The MIL
will go out on the 4th start cycle if the condition does not reoccur.
In the event the DTC is not related to an engine shut down or an oxygen sensor fault and the condition
causing the MIL illumination (DTC) no longer exists, the MIL will go out at the next run cycle.
If the condition is serviced by a technician and the DTC is cleared using a Diagnostic Service Tool (DST), the
MIL will go out immediately.
Diagnostic Trouble Codes (DTC) are permanently retained in the historic DTC section until cleared with a DST
or the auto clear requirements are met. The auto clear feature will clear out historic faults after 40 run cycles.
What are the requirements for a run cycle?
A run cycle is when the engine speed is above the "run speed" set point for 1.5 seconds or longer. The "run
speed" is the transition point when the ECM recognizes the engine is going from the cranking parameters to
the engine running parameters. The run speed is typically set at 450 rpm.
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