Isuzu 4HL1 Workshop Manual page 68

1A-66 Engine Control System
F3: Actuator F3: EGR
Test Control Test
When a fault
is found in
"F3: EGR
Control Test"
F4: Glow
Time Relay
Test
When a fault
is found in
"F4: Glow
Time Relay
Test"
Tech 2 typical data values
The data list is used to check the condition of the
vehicle (engine). The reference values (typical values)
are compared to the data acquired from the actual
vehicle to determine the current situation, for example,
This test aims at checking the working condition of the EGR valve and EGR valve
position sensor.
Test procedure:
1. Select "EGR 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 EGR control is correctly
executed.
Test result:
EGR Target Lift Position (mm)
EGR Current Position (mm)
EGR Duty Cycle (%)
EGR Position Sensor (V)
Difference Between Desired And Actual Values (mm)
When a fault is found in this test, identify regular error, irregular error, or fixed
indication.
Possible causes:
1. The EGR Target Lift valve position is fixed (no change):
Tech 2 communication error occurs or the ECM is faulty.
2. The EGR Current valve position does not follow the EGR Target Lift valve
position:
• Following under regular error = The problem lies in accuracy of EGR valve
position sensor.
• Following under irregular error = The problem lies in deformed EGR valve,
contamination, foreign material mixing-in, unstable or aged motor power supply,
unstable battery voltage, aged motor functions, or electrical or mechanical noise.
• Fixed indication of actual intake throttle position = The problem lies in shorted
EGR valve position system, faulty sensor, stuck EGR valve, or faulty motor.
This test aims at checking the working condition of the glow relay and the integrity
of the glow lamp bulb.
Test procedure:
1. Select "Glow Time Relay Test" from "Actuator Test".
2. Press "Run" or "Stop" soft key to check working sounds of the glow relay and
the operation of the glow lamp.
3. When the glow relay and glow lamp work as shown below, the warm-up control
is correctly performed.
Test result:
• Pressing "Run" soft key:
The glow relay generates sounds and the glow lamp is lit.
• Pressing "Stop" soft key:
The glow relay generates sounds and the glow lamp is turned off.
Possible causes:
1. No sound is generated: The glow relay system suffers from open wiring or
short, or the relay is faulty.
2. The glow lamp is not turned on after "Run" soft key is hit: The glow lamp system
suffers from open wiring or the lamp bulb filament is broken.
3. The glow lamp is not turned off after "Stop" soft key is hit: The glow lamp
system circuit is shorted to ground .
Item
temporary or permanent deviation, so that you can
diagnose the vehicle (engine) and think out appropriate
repair plan. (The menu in your Tech 2 may differ from
that shown above due to software version. Also, the
menu may be changed without prior notice.)
Increase Decrease
instruction instruction
Increase Decrease
Increase Decrease
Increase Decrease
Increase Decrease
within ±1