Isuzu N-Series. Manual - part 677

6E-130    Engine Control System (4HK1) 

4

1.

Turn OFF the ignition.

2.

Disconnect the FRP sensor harness
connector.

3.

Connect a DMM between the signal circuit of
the FRP sensor harness (pin 2 of E-113
connector) and a known good ground.

4.

Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than specified value?

5.5 volts

Go to Step 10

Go to Step 5

5

1.

Turn OFF the ignition.

2.

Connect a test lamp between the signal circuit
of the FRP sensor harness (pin 2 of E-113
connector) and a known good ground.

3.

Connect a DMM between the probe of the test
lamp and a known good ground.

4.

Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified value?

4.5 volts

Go to Step 9

Go to Step 6

6

1.

Turn OFF the ignition.

2.

Connect a 3-amp fused jumper wire between
the signal circuit and the low reference circuit
of the FRP sensor harness (pins 1 and 2 of E-
113 connector).

3.

Turn ON the ignition, with the engine OFF.

4.

Observe the FRP Sensor parameter with the
Tech 2.

Is the FRP Sensor parameter less than the
specified value?

0.7 volts

Go to Step 11

Go to Step 7

7

1.

Test the low reference circuit between the
engine control module (ECM) (pin 101 of E-
111 connector) and the FRP sensor (pin 1 of
E-113 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 15

Go to Step 8

8

1.

Test the signal circuit between the ECM (pins
82 and 90 of E-111 connector) and the FRP
sensor (pin 2 of E-113 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 15

Go to Step 12

9

1.

Test the signal circuits between the ECM (pins
82 and 90 of E-111 connector) and the FRP
sensor (pin 2 of E-113 connector) for a short to
any 5 volts reference circuit.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 14

Step

Action

Value(s)

Yes

No

 Engine Control System (4HK1)    6E-131

10

Important:
The FRP sensor may be damaged if the sensor
signal circuit is shorted to a voltage source.

1.

Test the signal circuits between ECM (pins 82
and 90 of E-111 connector) and the FRP
sensor (pin 2 of E-113 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 15

Go to Step 14

11

1.

Turn OFF the ignition.

2.

Inspect for an intermittent and for poor
connections at the harness connector of the
FRP sensor (pins 1 and 2 of E-113 connector).

3.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 13

12

1.

Turn OFF the ignition.

2.

Disconnect the ECM harness connector.

3.

Inspect for an intermittent and for poor
connections on the FRP sensor circuits at the
harness connector of the ECM (pins 82, 90
and 101 of E-111 connector).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 14

13

Replace the FRP sensor. Refer to Fuel Rail
Pressure (FRP) Sensor Replacement in this
section.

Did you complete the replacement?

—

Go to Step 15

—

14

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 15

—

15

1.

Reconnect all previously disconnected
harness connector(s).

2.

Clear the DTCs with the Tech 2.

3.

Turn OFF the ignition for 30 seconds.

4.

Start the engine.

5.

Operate the vehicle within the Conditions for
Running the DTC.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 16

16

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-132    Engine Control System (4HK1) 

P0201 (Flash Code 271)

Circuit Description
The engine control module (ECM) calculates the
optimum fuel injection ON time using data sent from
various engine sensors. The ECM supplies a high
voltage along with grounding the fuel injector control
circuit when it needs to energize the fuel injector (turn it
ON). The ECM also supplies battery voltage to the fuel
injector solenoid control circuit to allow for fault
detection. If the cylinder number 1 fuel injector solenoid
control circuit is open circuit, shorted to voltage or
shorted to the common 1 fuel injector drive circuit, this
DTC will set.

Condition for Running the DTC

• DTCs P0204, P0611 and P1261 are not set.
• The ignition switch is ON.
• The battery voltage is more than 18 volts.
• The engine is running.

Condition for Setting the DTC

• The ECM detects that the cylinder number 1 fuel

injector solenoid coil control circuit is open circuit,
shorted to voltage or shorted to common 1 fuel
injector drive circuit during engine rotations.

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 P0201 (Flash Code 271)
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 Diagnostic 

Aids

3

1.

Turn OFF the ignition.

2.

Disconnect the in-line harness connector (H-
125) from the cylinder head cover case.

3.

Connect a DMM between the common 1 fuel
injector drive circuit (pin 1 of H-125 female
side connector) and a known good ground.

4.

Turn ON the ignition, with the engine OFF.

Is the DMM voltage less than the specified value?

1.0 volt

Go to Step 4

Go to Step 9

4

Connect a DMM between the cylinder number 1
fuel injector control circuit (pin 5 of H-125 female
side connector) and a known good ground.

Is the DMM voltage less than the specified value?

16.0 volts

Go to Step 5

Go to Step 10

5

Is the DMM voltage more than the specified value
at Step 4?

12.0 volts

Go to Step 6

Go to Step 11

 Engine Control System (4HK1)    6E-133

6

1.

Inspect for an intermittent and for a poor
connection at the in-line harness connector
(pin 5 of H-125 connector).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 7

7

1.

Remove the cylinder head cover. Refer to Fuel
Injector Replacement in this section.

2.

Inspect the fuel injector harness for loose
injector terminal nuts, objects touching injector
terminals.

3.

Inspect for an intermittent and for a poor
connection at the in-line harness connector
(pin 5 of H-126 connector).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 8

8

1.

Test the cylinder number 1 fuel injector
solenoid control circuit between the fuel
injector terminal (pins 1, 2 and 3 of E-138
connector) and the in-line harness connector
(pins 1, 4 and 5 of H-126 connector) for the
following conditions:

• An open circuit
• A short to the common 1 fuel injector

drive circuit

• High resistance

2.

Repair or replace the injector harness as
necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 13

9

1.

Test the cylinder number 1 fuel injector
solenoid control circuit and common 1 fuel
injector drive circuit for a short to each other
between the engine control module (ECM)
(pins 119 and 121 of E-111 connector) and the
in-line harness connector (pins 1 or 4 and 5 of
H-125 connector).

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 14

10

1.

Test the cylinder number 1 fuel injector
solenoid control circuit between the ECM (pin
119 of E-111 connector) and the in-line
harness connector (pin 5 of H-125 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 15

Go to Step 14

11

1.

Test the cylinder number 1 fuel injector
solenoid control circuit between the ECM (pin
119 of E-111 connector) and the in-line
harness connector (pin 5 of H-125 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 15

Go to Step 12

Step

Action

Value(s)

Yes

No