Isuzu N-Series. Service manual - part 766

Engine Control System (4JH1) 6E-115

Turn OFF the ignition.

Disconnect the engine control module (ECM)
harness connector.

Turn ON the ignition, with the engine OFF.

Connect a 3-amp fused jumper wire between
the glow indicator lamp control circuit of the
ECM harness connector (pin 43 of B-234
connector) and a known good ground.

Does the glow indicator lamp illuminate?

—

Go to Step 11

Go to Step 7

Turn OFF the ignition.

Remove the instrument panel cluster (IPC).

Remove the glow indicator bulb from the IPC
(meter assembly).

Is the glow indicator bulb burned out?

—

Go to Step 15

Go to Step 8

Disconnect the IPC harness B-51 connector.

Connect a test lamp between the voltage feed
circuit of the glow indicator lamp (pin 8 of B-51
connector) and a known good ground.

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

—

Go to Step 9

Go to Step 12

Turn OFF the ignition.

Reconnect the ECM harness connector.

Connect a test lamp between the voltage feed
circuit and control circuit of the glow indicator
lamp (pins 6 and 8 of B-51 connector).

Turn ON the ignition, with the engine OFF.

Perform the Glow Indicator test with the Tech
2.

Command the Glow Indicator ON with the
Tech 2.

Does the test lamp turn ON when commanded ON
with the Tech 2?

—

Go to Step 14

Go to Step 13

Test the control circuit of the glow indicator
lamp between the ECM (pin 43 of B-234
connector) and the IPC (pin 6 of B-51
connector) for a short to ground.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 19

Go to Step 18

Turn OFF the ignition.

Disconnect the ECM harness connector.

Inspect for an intermittent and for a poor
connection on the glow indicator lamp control
circuit at the harness connector of the ECM
(pin 43 of B-234 connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 19

Go to Step 18

Repair the open circuit or high resistance on the
voltage feed circuit of the glow indicator lamp
between the IPC (pin 8 of B-51 connector) and
Meter (10A) fuse (F-16).

Did you complete the repair?

—

Go to Step 19

—

Step

Action

Value(s)

Yes

6E-116 Engine Control System (4JH1)

Repair the open circuit or high resistance on
the control circuit of the glow indicator lamp
between the ECM (pin 43 of B-234 connector)
and the IPC (pin 6 of B-51 connector).

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 19

—

Turn OFF the ignition.

Inspect for an intermittent and for poor
connections on the glow indicator lamp
circuits at the IPC (pins 6 and 8 of B-51
connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 19

Go to Step 16

Replace the glow indicator bulb.

Did you complete the replacement?

—

Go to Step 19

—

Repair or replace the IPC (meter assembly).

Did you complete the repair or replacement?

—

Go to Step 19

—

Turn OFF the ignition for 30 seconds.

Turn ON the ignition for 30 seconds, with the
engine OFF.

Monitor the DTC Information with the Tech 2.

Does the DTC fail this ignition?

—

Go to Step 18

Go to Diagnostic

Aids

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 19

—

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

Clear the DTCs with the Tech 2.

Turn OFF the ignition for 30 seconds.

Start the engine.

Monitor the DTC Information with the Tech 2.

Did the DTC fail this ignition?

—

Go to Step 2

Go to Step 20

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

Engine Control System (4JH1) 6E-117

P0381 (Symptom Code 8) (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 a short
to battery or ignition voltage 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 high voltage condition

on the glow indicator lamp control circuit for longer
than 1 second when the lamp 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.

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).

Test Description
The number below refers to the step number on the
diagnostic table.
3. If the control circuit of the glow indicator lamp
between the ECM and the IPC is normal, the control
circuit voltage low DTC P0381 (Symptom Code 4) will
set.

DTC P0381 (Symptom Code 8) (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

Did you perform the Diagnostic System Check –
Engine Controls?

—

Go to Step 2

Go to Diagnostic

System Check –

Engine Controls

Install the Tech 2.

Turn ON the ignition, with the engine OFF.

Perform the Glow Indicator test with the Tech
2.

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 Diagnostic

Aids

Go to Step 3

Turn OFF the ignition.

Remove the instrument panel cluster (IPC) in
order to disconnect the IPC harness B-51
connector.

Disconnect the IPC harness B-51 connector.

Turn ON the ignition for 30 seconds, with the
engine OFF.

Monitor the Diagnostic Trouble Code (DTC)
Information with the Tech 2.

Does DTC P0381 (Symptom Code 4) set, but not
DTC P0381 (Symptom Code 8)?

—

Go to Step 5

Go to Step 4

6E-118 Engine Control System (4JH1)

Test the control circuit of the glow indicator
lamp between the engine control module
(ECM) (pin 43 of B-234 connector) and the
IPC (pin 6 of B-51 connector) for a short to
battery or ignition voltage.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 7

Go to Step 6

Repair or replace the IPC (meter assembly).

Did you complete the repair or replacement?

—

Go to Step 7

—

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

—

Reconnect all previously disconnected
harness connector(s).

Clear the DTCs with the Tech 2.

Turn OFF the ignition for 30 seconds.

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

°C [77°F]).

Turn ON the ignition, with the engine OFF.

Monitor the DTC Information with the Tech 2.

Did the DTC fail this ignition?

—

Go to Step 2

Go to Step 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

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