Isuzu N-Series. Manual - part 764

Engine Control System (4JH1) 6E-107

P0335 (Symptom Code E) (Flash Code 43)

Circuit Description
The crankshaft position (CKP) sensor is located on top
of the flywheel housing. The engine control module
(ECM) calculates the engine speed and exact position
of the crankshaft based on the signal from the CKP
sensor. If the ECM detects an engine overrun
condition, this DTC will set.

Condition for Running the DTC

• The ignition switch is ON.

Condition for Setting the DTC

• The ECM detects that the engine speed is higher

than 5700 RPM for 0.2 seconds.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM cuts fuel injection.

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

• Ensure the sensor is tight and the flywheel

circumference is not damaged.

Notice:

• This DTC is caused by an engine overspeed

condition, which was most likely caused by driver
error (i.e. downshifting a manual transmission on
a steep grade). Ensure there are no signs of
engine damage. Excessive engine overspeed
may damage internal engine components.

DTC P0335 (Symptom Code E) (Flash Code 43)

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.

Start the engine.

Observe the Engine Speed parameter with the
Tech 2.

Accelerate the engine between idle and
W.O.T. (accelerator pedal full travel) many
times while observing the Tech 2.

Does the Engine Speed parameter ever exceed the
specified value?

5000 RPM

Go to Step 4

Go to Step 3

Ask the driver if overrun is caused by gear slip-out,
shift error, down-slope diving, etc. If engine
overrun has experienced, the engine must be
inspected and repaired as necessary.

Did you complete the action?

—

Go to Step 7

—

Remove the crankshaft position (CKP) sensor.
Refer to CKP Sensor replacement in this
section.

Visually inspect the CKP sensor for the
following conditions:

• For physical damage
• For being loose
• For improper installation

Did you find and correct the condition?

—

Go to Step 7

Go to Step 5

Visually inspect the flywheel circumference for
damage.

Did you find and correct the condition?

—

Go to Step 7

Go to Step 6

6E-108 Engine Control System (4JH1)

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.

Start the engine.

Observe the Engine Speed parameter with the
Tech 2.

Accelerate the engine between idle and
W.O.T. (accelerator pedal full travel) many
times while observing the Tech 2.

Does the Engine Speed parameter ever exceed the
specified value?

5000 RPM

Go to Step 4

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

Engine Control System (4JH1) 6E-109

P0380 (Symptom Code 4) (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
an open circuit or short to ground 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 low voltage condition on

the glow relay control circuit for longer than 3
seconds when the relay 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.

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 4) (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

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 Relay test with the Tech 2.

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

Turn OFF the ignition.

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

Turn ON the ignition, with the engine OFF.

Command the Glow Relay ON with the Tech
2.

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

—

Go to Step 10

Go to Step 4

Turn OFF the ignition.

Remove the glow relay.

Connect a test lamp between the voltage feed
circuit of the glow relay coil side (pin 4 of X-20
connector) and a known good ground.

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

—

Go to Step 5

Go to Step 7

6E-110 Engine Control System (4JH1)

Turn OFF the ignition.

Connect a test lamp between the control
circuit of the glow relay (pin 5 of X-20
connector) and battery voltage.

Turn ON the ignition, with the engine OFF.

Does the test lamp continuously illuminate (the test
lamp blinks then goes out normally if the engine
coolant temperature lower than 30

°C [86°F])?

—

Go to Step 8

Go to Step 6

Keep the test lamp with connected.

Command the Glow Relay ON with the Tech
2.

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

—

Go to Step 10

Go to Step 9

Repair the voltage feed circuit between the ECM
main relay (pin 5 of X-14 connector) and the glow
relay (pin 4 of X-20 connector) for an open circuit or
high resistance.

Did you complete the repair?

—

Go to Step 14

—

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 ground.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 14

Go to Step 13

Test the control circuit of the glow relay
between the ECM (pin 94 of B-233 connector)
and the glow relay (pin 5 of X-20 connector)
for an open circuit or high resistance.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 14

Go to Step 11

Turn OFF the ignition.

Inspect for an intermittent and for poor
connections on the glow relay terminals (pins
4 and 5 of X-20 connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 14

Go to Step 12

Turn OFF the ignition.

Disconnect the ECM harness connector.

Inspect for an intermittent and for a poor
connection on the glow relay control circuit at
the harness connector of the ECM (pin 94 of
B-233 connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 14

Go to Step 13

Replace the glow relay.

Did you complete the replacement?

—

Go to Step 14

—

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 14

—

Step

Action

Value(s)

Yes

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