Isuzu 4HL1, Workshop Manual

Page: 66 / 267

1A-64 Engine Control System
Actuator test
F3: Actuator
Test F0: Common
Rail Pressure
Control Test This test aims at checking the common rail pressure is correctly controlled by the
ECM and common rail pressure sensor.
Test procedure:
1. Select "Common Rail Pressure Control Test" from "Actuator Test".
2. Press "Decrease" or "Increase" soft key to check the data list.
3. When the data list changes as shown below, the common rail pressure control
is correctly performed.
Test result
Item Increase
instruction
Decrease
instruction
Desired Rail Pressure (MPa) Increase Decrease
Actual Rail Pressure (MPa) Increase Decrease
SCV Duty Ratio (%) Decrease Increase
Common Rail Pressure Sensor (V) Increase Decrease
SCV Current (mA) Decrease Increase
Difference Between Desired And Actual Values (MPa) within ±1
When a fault
is found in
"F0: Common
rail Pressure
Control Test" When a fault is found in this test, identify regular error, irregular error, or fixed
indication.
Possible causes:
1. The desired rail pressure is fixed:
Tech 2 communication error occurs or the ECM is faulty.
2. The actual rail pressure does not follow the desired rail pressure:
• Following under regular error = The problem lies in accuracy of common rail
pressure sensor.
• Following under irregular error =The problem lies in collapsed fuel pipe, foreign
material mixing-in, poor fuel system vent, unstable battery voltage, SCV aging,
supply pump aging, or electrical or mechanical noise.
• Fixed indication of actual rail pressure = The problem lies in shorted common rail
pressure sensor system, faulty sensor, shorted SCV system, or faulty SCV.