Actuator Test - Isuzu 4HL1 Workshop Manual

1A-64 Engine Control System

Actuator test

F3: Actuator F0: Common
Test Rail Pressure
Control Test
When a fault
is found in
"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
Desired Rail Pressure (MPa)
Actual Rail Pressure (MPa)
SCV Duty Ratio (%)
Common Rail Pressure Sensor (V)
SCV Current (mA)
Difference Between Desired And Actual Values (MPa)
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.
Item Increase Decrease
instruction instruction
Increase Decrease
Increase Decrease
Decrease Increase
Increase Decrease
Decrease Increase
within ±1