Isuzu N 2008 Series Workshop Manual page 376

Legend
1. Exhaust brake valve
2. Exhaust temperature sensor 2 (in front of oxygen
catalyst)
3. Exhaust temperature sensor 1 (in front of filter)
The DPD is a system that uses an oxidation catalyst to
clean the CO and HC, and a filter to collect PM
discharged from the engine. When PM accumulated in
the filter, regeneration is performed. The ECM detects
the condition of PM accumulations from the exhaust
differential pressure sensor or from mileage. When it is
reached to a certain amount of PM accumulations or a
certain length of mileage, the automatic regeneration
starts. If the automatic regeneration cannot be
completed by some reason, the manual regeneration is
requested to the driver by blinking the DPD amber lamp
or "PUSH DPD SWITCH" indicator on the instrument
panel cluster. During regeneration, the temperature
inside the filter is raised, and the accumulated PM is
burned off. In order to adjust to optimized temperature,
the ECM detects exhaust temperature using the
exhaust temperature sensors, and then raises the
temperature by controlling fuel injections, the exhaust
brake valve and exhaust throttle valve to burn off the
accumulated PM. Once the regeneration starts, it must
be finished within a certain time. After regeneration is
finished, a purification of the filter is judged by
monitoring the exhaust differential pressure.
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Engine Control System (4JJ1)
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2
6
4. Exhaust differential pressure sensor
5. Exhaust throttle valve
6. DPD assembly
Exhaust Differnetial Pressure Sensor
The exhaust differential pressure sensor is attached to
the chassis frame near the DPD assembly. The
exhaust differential pressure sensor is a transducer
that varies voltage according to changes of the exhaust
gas differential pressure between in front and in rear of
DPD filter. The exhaust differential pressure sensor
provides a signal to the ECM on the signal circuit,
which is relative to the differential pressure changes in
front and in rear of DPD filter. The ECM should detect a
low signal voltage at a low differential pressure, such
as small PM accumulation. The ECM should detect
high signal voltage at high differential pressure, such as
large PM accumulation.
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5
1A-373
LNW76ESF000901
MFW4ADSH002301