Isuzu N-Series. Manual - part 765

 Engine Control System (4JH1)    6E-111

14

1.

Reconnect all previously disconnected relay
or harness connector(s).

2.

Clear the DTCs with the Tech 2.

3.

Turn OFF the ignition for 30 seconds.

4.

Start the engine and warm up (allow engine
coolant temperature to reach at least 35

°C

[95

°F]).

5.

Monitor the DTC Information with the Tech 2.

Did the DTC fail this ignition?

—

Go to Step 2

Go to Step 15

15

Observe the DTC Information with the Tech 2.

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic 

Trouble Code (DTC) 

List

System OK

Step

Action

Value(s)

Yes

No

6E-112    Engine Control System (4JH1) 

P0380 (Symptom Code 8) (Flash Code 66)

Circuit Description
The engine control module (ECM) controls the glow
relay which supplies power to the glow plugs based on
engine coolant temperature.  In the after glow phase,
the glow indicator light is not illuminated but glow plugs
remain active for a certain period.  If the ECM detects a
short to battery or ignition voltage on the glow relay
control circuit, this DTC will set.

Condition for Running the DTC

• The ignition switch is ON.

Condition for Setting the DTC

• The ECM detects that the high voltage condition

on the glow relay control circuit for longer than 1
second when the relay is commanded ON.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

Condition for Clearing the MIL/DTC

• The ECM turns OFF the MIL when the diagnostic

runs and does not fail.

• A history DTC clears after 40 consecutive driving

cycles without a fault.  Or clear with the Tech 2.

Notice:

• The glow relay is commanded OFF with ignition

ON and engine OFF when the engine coolant
temperature is reached at 30

°C (86°F).

• The glow relay is commanded OFF with engine run

when the engine coolant temperature is reached at
30

°C (86°F).

DTC P0380 (Symptom Code 8) (Flash Code 66)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check –
Engine Controls?

—

Go to Step 2

Go to Diagnostic 

System Check – 

Engine Controls

2

1.

Install the Tech 2.

2.

Turn ON the ignition, with the engine OFF.

3.

Perform the Glow Relay test with the Tech 2.

4.

Command the Glow Relay ON with the Tech
2.

Does the glow relay click when commanded ON
with the Tech 2?

—

Go to Diagnostic 

Aids

Go to Step 3

3

1.

Turn OFF the ignition.

2.

Replace the glow relay with the starter relay or
replace with a known good relay.

3.

Turn ON the ignition, with the engine OFF.

4.

Command the Glow Relay ON with the Tech
2.

Does the glow relay click when commanded ON
with the Tech 2?

—

Go to Step 5

Go to Step 4

4

1.

Test the control circuit of the glow relay
between the engine control module (ECM)
(pin 94 of B-233 connector) and the glow relay
(pin 5 of X-20 connector) for a short to battery
or ignition voltage.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 7

Go to Step 6

5

Replace the glow relay.

Did you complete the replacement?

—

Go to Step 7

—

 Engine Control System (4JH1)    6E-113

6

Important:
Replacement ECM must be programmed.

Replace the ECM.  Refer to Engine Control Module
(ECM) Replacement in this section.

Did you complete the replacement?

—

Go to Step 7

—

7

1.

Reconnect all previously disconnected relay
or harness connector(s).

2.

Clear the DTCs with the Tech 2.

3.

Turn OFF the ignition for 30 seconds.

4.

Cool down the engine as necessary (allow
engine coolant temperature to cool down at
least 25

°C [77°F]).

5.

Start the engine.

6.

Monitor the DTC Information with the Tech 2.

Did the DTC fail this ignition?

—

Go to Step 2

Go to Step 8

8

Observe the DTC Information with the Tech 2.

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic 

Trouble Code (DTC) 

List

System OK

Step

Action

Value(s)

Yes

No

6E-114    Engine Control System (4JH1) 

P0381 (Symptom Code 4) (Flash Code 67)

Circuit Description
The glow indicator lamp is located on the instrument
panel cluster (IPC).  The glow control system is
operated when the engine coolant temperature is low,
which allows easier engine starting.  If the ignition
switch is turned ON when the engine coolant
temperature is low, the engine control module (ECM)
illuminates the glow indicator lamp and turns ON the
glow plugs.  After a fixed time passes, the ECM turns
OFF the glow indicator lamp and the glow plugs.  The
ECM monitors the glow indicator lamp control circuit for
conditions that are incorrect for the commanded state
of the glow indicator lamp.  If the ECM detects an open
circuit or short to ground on the glow indicator control
circuit, this DTC will set.

Condition for Running the DTC

• The ignition switch is ON.

Condition for Setting the DTC

• The ECM detects that the low voltage condition on

the glow indicator lamp control circuit for longer
than 3 seconds when the lamp is commanded
OFF.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

Condition for Clearing the MIL/DTC

• The ECM turns OFF the MIL when the diagnostic

runs and does not fail.

• A history DTC clears after 40 consecutive driving

cycles without a fault.  Or clear with the Tech 2.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Notice:

• The glow indicator lamp is commanded OFF with

the ignition ON and engine OFF when the engine
coolant temperature is reached at 30

°C (86°F).

DTC P0381 (Symptom Code 4) (Flash Code 67)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check –
Engine Controls?

—

Go to Step 2

Go to Diagnostic 

System Check – 

Engine Controls

2

1.

Install the Tech 2.

2.

Turn ON the ignition, with the engine OFF.

3.

Perform the Glow Indicator test with the Tech
2.

4.

Command the Glow Indicator ON with the
Tech 2.

Does the glow indicator lamp turn ON when
commanded ON with the Tech 2?

—

Go to Step 3

Go to Step 4

3

Command the Glow Indicator OFF with the Tech 2.

Does the glow indicator lamp OFF?

—

Go to Step 17

Go to Step 10

4

1.

Turn OFF the ignition.

2.

Inspect the Meter (10A) fuse (F-16) in the
glove box fuse block.

Is the Meter (10A) fuse (F-16) open?

—

Go to Step 5

Go to Step 6

5

Replace the Meter (10A) fuse (F-16).  If the fuse
continues to open, repair the short to ground on
one of the circuits that fed by the Meter (10A) fuse
(F-16) or replace the shorted attached component
fed by the Meter (10A) fuse (F-16).

Did you complete the repair?

—

Go to Step 19

—