Isuzu 4JA1 Workshop Manual page 480

6E-226 Engine Control System (4JH1)
Glow Control System Check
Description
The glow control system consists of the engine control
module (ECM), the glow relay and glow plugs. The glow
control system is operated when the engine coolant
temperature is low, which allows easier engine starting.
The ECM commands the glow relay ON for a certain
length of time at ignition switch is ON with engine OFF.
In after glow phase, the glow plugs remain energized for
a certain period with engine run.
Step
1 Did you perform the Diagnostic System Check-
Engine Controls?
2 1. Install the scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Monitor the Diagnostic Trouble Code (DTC)
Information of the engine control system with the
scan tool and check whether following DTC(s) is
set:
•
P0115 (Symptom Code 1 & 2)
•
P0380 (Symptom Code 4 & 8)
•
P0381 (Symptom Code 4 & 8)
Are any of the above DTC(s) set?
3 1. Turn OFF the ignition.
2. Make sure the metal bus bar that connects
switched battery voltage supply terminal (E-49)
and all glow plugs is secured tightly.
3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the metal bus bar
(glow plug power supply E-49 terminal) and a
known good ground.
5. Perform the Glow Relay test with the scan tool.
6. Command the Glow Relay ON with the scan tool
while observing the test lamp.
Does the test lamp turn ON only when commanded
ON with the scan tool?
4 1. Turn OFF the ignition.
2. Remove the metal bus bar from the glow plugs.
3. Measure resistance of each glow plug between
the glow plug terminals and a known good
ground. Make sure to record all measurements
and take them quickly as to not allow engine
temperature changes between measurements.
Are the resistances within the specified value each
other?
Action
Glow Control Operation
• The pre glow control system operates when the
engine coolant temperature is less than 30°C
(86°F).
• The after glow control system operates when the
engine coolant temperature is less than 60°C
(140°F).
Glow Control System Check
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views
Value(s) Yes

Go to Step 2

Refer to Applicable
DTC

Go to Step 4
1Ω
System OK
No
Go to Diagnostic
System Check-
Engine Controls
Go to Step 3
Go to Step 5
Go to Step 15