Diesel Particulate Defuser (Dpd) Control System Check - Isuzu 2008MY N Series Workshop Manual

1A-336 Engine Control System (4HK1)

Diesel Particulate Defuser (DPD) Control System Check

Description
The ECM detects the condition of PM accumulations
from the exhaust differential pressure sensor attached
to the chassis frame near the diesel particulate defuser
(DPD) assembly or from mileage. 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
filter. When it is reached to a certain amount of PM
accumulations or a certain length of mileage, the
automatic regeneration
regeneration cannot be completed by some reason, the
manual regeneration is requested to the driver by
blinking the DPD lamp or "PUSH DPD SWITCH"
indicator on the instrument panel cluster. 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 an exhaust differential
pressure. If an excessive PM accumulation has been
detected, the regeneration will not start since
uncontrolled burning might be happened during
regeneration process.
The DPD Status Table is used to determine type of the
DPD filter regeneration procedure by comparing the
DPD Accumulation Status parameter and the DPD
Distance Status parameter. To use this table, observe
both parameters with a scan tool, and plot both
readings on the DPD status table. The intersected
range indicates A, B, C or D. (e.g. DPD Accumulation
Status is 3 and DPD Distance Status is 1. The range is
located in B)
5
4
3
2
A
1
0
0
DPD Distance Status
Circuit/ System Testing Diesel Particulate Defuser (DPD) Control System Check
Step
Did you perform the Diagnostic System Check
1
- Engine Controls?
starts. If the
C
B
D
1 2 3 4
LNW76ESH003501
Action
Range A: Normal range
Range B: DPD lamp or "PUSH DPD SWITCH" indicator
blinks but manual regeneration is possible.
Range C: Exhaust differential pressure is excessive
high range and manual regeneration is inhibited.
Range D: Distance status is abnormal range and
manual regeneration is inhibited.
Test Description
The number below refers to the step number on the
automatic Circuit/ System Table.
6. 8. 9. If the regeneration is not started, any DTCs may
be set which inhibits regeneration control. If no DTC is
set, use the scan tool to observe the Vehicle Speed,
Accelerator Pedal Position, Neutral Switch, Idle Up
Sensor and PTO Switch parameters which allows the
DPD regeneration control. Refer to Engine Controls
Schematic and Scan Tool Data List for diagnosis.
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Value(s)
—
Yes
Go to Diagnostic
System Check -
Go to Step 2 Engine Controls
No