Isuzu N-Series. Manual - part 694

6E-198    Engine Control System (4HK1) 

P0612 (Flash Code 34)

Circuit Description
The charge up circuit in the engine control module
(ECM) steps up the voltage for fuel injectors and is
divided into two banks, common 1 and 2. The common
1 covers fuel injectors in cylinders 1 and 4, and the
common 2 covers fuel injectors in cylinders 2 and 3. If
the common 2 fuel injector charge up voltage circuit in
the ECM is excessively low, this DTC will set.

Condition for Running the DTC

• The ignition switch is ON.
• The battery voltage is more than 18 volts.

Condition for Setting the DTC

• The ECM detects that the common 2 fuel injector

charge up circuit is insufficient charge.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM limits accelerator control range.
• The ECM inhibits pilot injection.

Condition for Clearing the MIL / DTC

• The ECM turns OFF the MIL when the key is

cycled after a current DTC clears.

• A current DTC clears when the diagnostic runs and

does not fail.

• A history DTC clears after 20 consecutive driving

cycles without a fault. Or clear with the Tech 2 or
accelerator pedal operation.

Diagnostic Aid

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

DTC P0612 (Flash Code 34)
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 OFF the ignition for 30 seconds.

3.

Start the engine.

4.

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

Does the DTC fail this ignition?

—

Go to Step 3

Go to Step 8

3

1.

Test each ground circuit between the engine
control module (ECM) (pins 1, 3, 4, 43, 62 and
81 of J-191 connector) and the chassis ground
terminal (J-9) for an open circuit or high
resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 4

4

1.

Turn OFF the ignition.

2.

Inspect for an intermittent, for poor tightening
and corrosion at the chassis ground terminal
(J-9).

3.

Repair the tightening or clean the corrosion as
necessary.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 5

5

1.

Test each ECM main relay voltage feed circuit
between the ECM (pins 2 and 5 of J-191
connector) and the ECM main relay (pin 2 of
X-18 connector) for high resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 6

 Engine Control System (4HK1)    6E-199

6

1.

Turn OFF the ignition.

2.

Disconnect the ECM harness connector.

3.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the ECM 1, 2, 3, 4, 5, 43, 62 and
81 of J-191 connector.

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 7

7

Important:
Replacement ECM must be programmed.

Replace the ECM. Refer to Engine Control Module
(ECM) Replacement / Fuel Injector ID Code Data
Programming in this section.

Did you complete the replacement?

—

Go to Step 8

—

8

1.

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

2.

Clear the DTCs with he Tech 2.

3.

Turn OFF the ignition for 30 seconds.

4.

Start the engine.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 9

9

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-200    Engine Control System (4HK1) 

P0615 (Flash Code 19)

Circuit Description
The engine control module (ECM) controls the starter
cut relay which de-energizes the starter relay based on
engine speed inputs. The starter cut relay uses
normally close type relay. During engine stopping, the
relay is closed to allow grounding the starter relay.
Once engine run, the ECM energizes the starter cut
relay to open the starter relay circuit and starter motor
is cut even the ignition is positioned at START. If the
ECM detects an improper voltage on the starter cut
relay control circuit, this DTC will set. This diagnostic
only applies manual transmission model.

Condition for Running the DTC

• The ignition switch is ON.
• The battery voltage is between 16 – 32 volts.

Condition for Setting the DTC
Either of following condition is met:

• The ECM detects a low voltage condition on the

starter cut relay control circuit when the relay is
commanded OFF for longer than 10 seconds.

• The ECM detects a high voltage condition on the

starter cut relay control circuit when the relay is
commanded ON for longer than 10 seconds.

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 key is

cycled after a current DTC clears.

• A current DTC clears when the diagnostic runs and

does not fail at next driving cycle.

• A history DTC clears after 20 consecutive driving

cycles without a fault. Or clear with the Tech 2 or
accelerator pedal operation.

Diagnostic Aid

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

DTC P0615 (Flash Code 19)
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 OFF the ignition for 30 seconds.

3.

Turn ON the ignition, with the engine OFF. DO
NOT start the engine.

4.

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

Does the DTC fail this ignition?

—

Go to Step 4

Go to Step 3

3

1.

Start the engine.

2.

Monitor the DTC Information with the Tech 2.

Does the DTC fail this ignition?

—

Go to Step 8

Go to Diagnostic 

Aids

4

Start the engine.

Does the engine start?

—

Go to Step 6

Go to Step 5

5

1.

Turn OFF the ignition.

2.

Replace the starter cut relay with the marker
lamp relay or replace with a known good relay.

3.

Start the engine.

Does the engine start?

—

Go to Step 14

Go to Step 9

 Engine Control System (4HK1)    6E-201

6

1.

Turn OFF the ignition.

2.

Remove the starter cut relay.

3.

Connect a test lamp between the starter cut
relay voltage feed circuit (pin 3 of X-26
connector) and a known good ground.

4.

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

—

Go to Step 7

Go to Step 10

7

1.

Reinstall the starter cut relay.

2.

Start the engine.

3.

Disconnect the starter cut relay.

4.

Connect a test lamp between the starter cut
relay control circuit (pin 5 of X-26 connector)
and battery voltage.

Does the test lamp illuminate?

—

Go to Step 12

Go to Step 11

8

1.

Test the starter cut relay control circuit
between the engine control module (ECM)
(pin 14 of J-191 connector) and the starter cut
relay (pin 5 of X-26 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 16

Go to Step 15

9

1.

Test the starter cut relay control circuit
between the ECM (pin 14 of J-191 connector)
and the starter cut relay (pin 5 of X-26
connector) for a short to ground.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 16

Go to Step 15

10

Repair the open circuit or high resistance on the
voltage feed circuit between the ECM (10A) fuse
and the starter cut relay (pin 3 of X-26 connector).
Check the ECM (10A) fuse first.

Did you complete the repair?

—

Go to Step 16

—

11

1.

Test the starter cut relay control circuit
between the ECM (pin 14 of J-191 connector)
and the starter cut relay (pin 5 of X-26
connector) for an open circuit or high
resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 16

Go to Step 13

12

1.

Turn OFF the ignition.

2.

Remove the starter cut relay.

3.

Inspect for an intermittent and for a poor
connection on each starter cut relay terminal.

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 16

Go to Step 14

Step

Action

Value(s)

Yes

No