Isuzu N-Series. Manual — part 665

6E-82 Engine Control System (4HK1)

P1271

24

ON

Accelerator
Pedal Position
(APP) Sensor 1-
2 Correlation

• DTCs P1630, P1631

and P1632 are not
set.

• The ignition switch is

ON.

• The ignition voltage

is more than 18
volts.

• The ECM detects

that the APP sensor
1 and sensor 2 are
more than 45% out
of range of each
other.

• Sensor 5V reference

circuit is high resistance.

• Sensor signal circuit is

high resistance.

• Sensor low reference

circuit is high resistance.

• Faulty sensor.
• Faulty ECM.
• Electromagnetic

interference and
electrical noise.

P1277

24

ON

Accelerator
Pedal Position
(APP) Sensor 1
Circuit Low
Voltage

• DTCs P1630 and

P1631 are not set.

• The ignition switch is

ON.

• The ignition voltage

is more than 18
volts.

• The ECM detects

that the APP sensor
1 signal voltage is
less than 0.2 volts.

• Sensor 5V reference

circuit is short to ground
or short to the low
reference circuit. (P1631
may also set.)

• Sensor 5V reference

circuit is open circuit,
high resistance.

• Sensor signal circuit is

open circuit, high
resistance, short to
ground or short to the
low reference circuit.

• Poor harness connector

connection.

• Faulty sensor.
• Faulty ECM.

P1278

24

ON

Accelerator
Pedal Position
(APP) Sensor 1
Circuit High
Voltage

• DTCs P1630 and

P1631 are not set.

• The ignition switch is

ON.

• The ignition voltage

is more than 18
volts.

• The ECM detects

that the APP sensor
1 signal voltage is
more than 4.9 volts.

• Sensor 5V reference

circuit is short to battery
or ignition voltage.
(P1631 may also set.)

• Sensor signal circuit is

short to battery, ignition
voltage or short to any
5V reference circuit.

• Sensor low reference

circuit is open circuit or
high resistance.

• Poor harness connector

connection.

• Faulty sensor.
• Faulty ECM.

DTC

Flash
Code

MIL

Status

DTC Name

Condition for Running

the DTC

Condition for Setting the

DTC

Possible Cause

Engine Control System (4HK1) 6E-83

P1282

24

ON

Accelerator
Pedal Position
(APP) Sensor 2
Circuit Low
Voltage

• DTCs P1630 and

P1632 are not set.

• The ignition switch is

ON.

• The ignition voltage

is more than 18
volts.

• The ECM detects

that the APP sensor
2 signal voltage is
less than 0.2 volts.

• Sensor 5V reference

circuit is short to ground
or short to the low
reference circuit. (P1632
may also set.)

• Sensor 5V reference

circuit is open circuit,
high resistance.

• Sensor signal circuit is

open circuit, high
resistance, short to
ground or short to the
low reference circuit.

• Poor harness connector

connection.

• Faulty sensor.
• Faulty ECM.

P1283

24

ON

Accelerator
Pedal Position
(APP) Sensor 2
Circuit High
Voltage

• DTCs P1630 and

P1632 are not set.

• The ignition switch is

ON.

• The ignition voltage

is more than 18
volts.

• The ECM detects

that the APP sensor
2 signal voltage is
more than 4.9 volts.

• Sensor 5V reference

circuit is short to battery
or ignition voltage.
(P1632 may also set.)

• Sensor signal circuit is

short to battery, ignition
voltage or short to any
5V reference circuit.

• Sensor low reference

circuit is open circuit or
high resistance.

• Poor harness connector

connection.

• Faulty sensor.
• Faulty ECM.

P1345

16

ON

Crankshaft
Position (CKP) –
Camshaft
Position (CMP)
Correlation

• DTCs P0335,

P0336, P0340 and
P0341 are not set.

• The ignition switch is

ON

• The CKP sensor

signal is detected.

• The CMP sensor

signal is detected.

• The ECM detects

that the CKP sensor
signals and CMP
sensor signals are
out of
synchronization
during engine
rotations.

• Incorrect engine

mechanical timing.

DTC

Flash
Code

MIL

Status

DTC Name

Condition for Running

the DTC

Condition for Setting the

DTC

Possible Cause

6E-84 Engine Control System (4HK1)

P1625

416

ON

Main Relay
System Error

ECM main relay open
stuck DTC

• DTC P1630 is not

set.

• The ignition switch is

ON.

• The ignition voltage

is more than 18
volts.

• The ignition ON time

is longer than 3
seconds.

ECM Main Relay Open
Stuck DTC

• The ECM detects a

low voltage
condition on the
ECM main relay
voltage feed circuit
when the relay is
commanded ON for
longer than 5
seconds.

ECM Main Relay Close
Stuck DTC

• The ECM detects

that the ECM has
been ON when the
relay is commanded
OFF for longer than
10 seconds.

• Relay switch side

voltage feed circuit is
open circuit or high
resistance.

• Relay switched voltage

feed circuit is short to
battery or high
resistance.

• Relay coil side voltage

supply circuit is short to
battery or high
resistance.

• Relay coil side ground

circuit is open circuit or
high resistance.

• Faulty relay.
• Faulty ECM

P1630

36

ON

Control Module
A/D Converter
Error

—

• The ECM detects a

malfunction in its
internal analog /
digital (A/D)
converter.

• Faulty ECM.

P1631

55

ON

5V Reference
Circuit 1

• DTC P1630 is not

set.

• The ignition switch is

ON.

• The battery voltage

is between 16 – 32
volts.

Either of following
condition is met:

• The ECM detects

that the 5 volts
reference circuit 1
voltage is less than
4.5 volts.

• The ECM detects

that the 5 volts
reference circuit 1
voltage is more than
5.5 volts.

• APP sensor 1 5V

reference circuit is short
to battery, ignition
voltage or short to
ground.

• Idle up sensor 5V

reference circuit is short
to battery, ignition
voltage or short to
ground.

• PTO throttle sensor 5V

reference circuit is short
to battery, ignition
voltage or short to
ground.

• Faulty APP sensor.
• Faulty idle up sensor.
• Faulty PTO throttle

sensor.

• Faulty ECM.

DTC

Flash
Code

MIL

Status

DTC Name

Condition for Running

the DTC

Condition for Setting the

DTC

Possible Cause

Engine Control System (4HK1) 6E-85

P1632

55

ON

5V Reference
Circuit 2

• DTC P1630 is not

set.

• The ignition switch is

ON.

• The battery voltage

is between 16 – 32
volts.

Either of following
condition is met:

• The ECM detects

that the 5 volts
reference circuit 2 or
5 voltage is less
than 4.5 volts.

• The ECM detects

that the 5 volts
reference circuit 2 or
5 voltage is more
than 5.5 volts.

• APP sensor 2 5V

reference circuit is short
to battery, ignition
voltage or short to
ground.

• FRP sensor 5V

reference circuit is short
to battery, ignition
voltage or short to
ground.

• EGR valve position

sensor 5V reference
circuit is short to battery,
ignition voltage or short
to ground.

• BARO sensor 5V

reference circuit is short
to battery, ignition
voltage or short to
ground.

• Faulty APP sensor.
• Faulty FRP sensor.
• Faulty EGR valve.
• Faulty BARO sensor.
• Faulty ECM.

P1633

55

ON

5V Reference
Circuit 3

• DTC P1630 is not

set.

• The ignition switch is

ON.

• The battery voltage

is between 16 – 32
volts.

Either of following
condition is met:

• The ECM detects

that the 5 volts
reference circuit 3 or
4 voltage is less
than 4.5 volts.

• The ECM detects

that the 5 volts
reference circuit 3 or
4 voltage is more
than 5.5 volts.

• Same as DTC P1634.

P1634

55

ON

5V Reference
Circuit 4

• DTC P1630 is not

set.

• The ignition switch is

ON.

• The battery voltage

is between 16 – 32
volts.

Either of following
condition is met:

• The ECM detects

that the 5 volts
reference circuit 3 or
4 voltage is less
than 4.5 volts.

• The ECM detects

that the 5 volts
reference circuit 3 or
4 voltage is more
than 5.5 volts.

• Boost pressure sensor

5V reference circuit is
short to battery, ignition
voltage or short to
ground.

• Faulty boost pressure

sensor.

• Faulty ECM.

DTC

Flash
Code

MIL

Status

DTC Name

Condition for Running

the DTC

Condition for Setting the

DTC

Possible Cause