Isuzu N-Series. Service manual - part 707

6E-250    Engine Control System (4HK1) 

P1283 (Flash Code 24)

Circuit Description
The accelerator pedal position (APP) sensor is
mounted on the accelerator pedal control assembly.
The sensor is made up of two individual sensors within
one housing. The engine control module (ECM) uses
the APP sensors to determine the amount of
acceleration or deceleration desired by the person
driving the vehicle via the fuel injector control. The APP
sensor 2 has the following circuits.

• 5 volts reference circuit
• Low reference circuit
• APP sensor 2 signal circuit

The ECM supplies 5 volts to the APP sensor 2 on the 5
volts reference circuit. The ECM also provides a ground
on the low reference circuit. The APP sensor 2
provides a signal to the ECM on the APP sensor 2
signal circuit, which is relative to the position changes
of the accelerator pedal angle. The ECM monitors the
APP sensor 2 signal for voltages outside the normal
range of the APP sensor 2. If the ECM detects an
excessively high APP sensor 2 signal voltage, this DTC
will set.

Condition for Running the DTC

• DTCs P1630 and P1632 are not set.
• The ignition switch is ON.
• The ignition voltage is more than 18 volts.

Condition for Setting the DTC

• The ECM detects that the APP sensor 2 signal

voltage is more than 4.9 volts.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM blinks the exhaust brake indicator lamp

when the diagnostic runs and fails.

• The ECM inhibits exhaust brake control.

Condition for Clearing the MIL / DTC

• The ECM turns OFF the MIL and exhaust brake

indicator lamp 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.

• APP sensor 2 may have an intermittent open

somewhere in the pedal range.

DTC P1283 (Flash Code 24)
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.

Fully depress and release the accelerator
pedal while observing the Accelerator Pedal
Position (APP) Sensor 2 parameter with the
Tech 2.

Does the APP Sensor 2 parameter ever exceed the
specified value?

4.8 volts

Go to Step 3

Go to Diagnostic 

Aids

3

1.

Start the engine.

2.

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

Is the DTC P1632 also set?

—

Go to Step 4

Go to Step 5

 Engine Control System (4HK1)    6E-251

4

1.

Turn OFF the ignition.

2.

Disconnect the APP sensor harness
connector.

3.

Turn ON the ignition, with the engine OFF.

4.

Observe the APP Sensor 2 parameter with the
Tech 2.

Is the APP Sensor 2 parameter less than the
specified value?

0.2 volts

Go to DTC P1632

Go to Step 7

5

1.

Turn OFF the ignition.

2.

Disconnect the APP sensor harness
connector.

3.

Turn ON the ignition, with the engine OFF.

4.

Observe the APP Sensor 2 parameter with the
Tech 2.

Is the APP Sensor 2 parameter less than the
specified value?

0.2 volts

Go to Step 6

Go to Step 7

6

1.

Turn OFF the ignition.

2.

Connect a test lamp between the low
reference circuit of the APP sensor 2 harness
(pin 3 of B-280 connector) and battery voltage.

3.

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

—

Go to Step 9

Go to Step 8

7

Important:
The APP sensor 2 may be damaged if the sensor
signal circuit is shorted to a voltage source.

1.

Test the signal circuit between the engine
control module (ECM) (pin 64 of J-191
connector) and the APP sensor 2 (pin 2 of B-
280 connector) for the following conditions:

• A short to battery or ignition voltage
• A short to any 5 volts reference

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 12

8

1.

Test the low reference circuit between the
ECM (pin 60 of J-191 connector) and the APP
sensor 2 (pin 3 of B-280 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 13

Go to Step 10

9

1.

Turn OFF the ignition.

2.

Inspect for an intermittent and for a poor
connection at the harness connector of the
APP sensor (pin 3 of B-280 connector).

3.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 11

Step

Action

Value(s)

Yes

No

6E-252    Engine Control System (4HK1) 

10

1.

Turn OFF the ignition.

2.

Disconnect the ECM harness connector.

3.

Inspect for an intermittent and for a poor
connection on the APP sensor 2 circuit at the
harness connector of the ECM (pin 60 of J-
191 connector).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 12

11

Replace the APP sensor. Refer to Accelerator
Pedal Position (APP) Sensor Replacement in this
section. (APP sensor 2 is internal to APP sensor
assembly)

Did you complete the replacement?

—

Go to Step 13

—

12

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 13

—

13

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.

Fully depress and release the accelerator
pedal while observing the APP Sensor 2
parameter with the Tech 2.

Does the APP Sensor 2 parameter ever exceed the
specified value?

4.8 volts

Go to Step 3

Go to Step 14

14

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

 Engine Control System (4HK1)    6E-253

P1345 (Flash Code 16)

Circuit Description
The crankshaft position (CKP) sensor is located on top
of the flywheel housing. There are 56 notches spaced
6

° apart and a 30° section that is open span. This open

span portion allows for the detection of cylinder #1 top
dead center (TDC).
The camshaft position (CMP) sensor is installed on the
cylinder head at the rear of the camshaft gear. The
CMP sensor detects a total of five through holes (four
holes arranged equally every 90

° and one reference

hole on the camshaft gear flange surface).
Detecting the open span portion from the CKP sensor
and one reference hole from the CMP sensor, the
engine control module (ECM) determines cylinder #1
compression top dead center (TDC) to ensure they
correlate with each other. If the ECM detects both
signals are out of synchronization, this DTC will set.

Condition for Running the DTC

• 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.

Condition for Setting the DTC

• The ECM detects that the CKP sensor signals and

CMP sensor signals are out of synchronization
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

• This DTC is caused by an incorrect mechanical

timing condition, which was most likely cased by
wrong installation of timing gear, flywheel or
camshaft.

DTC P1345 (Flash Code 16)

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. If engine does not start,
crank over the engine for 10 seconds.

4.

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

Is the DTC P0335, P0336, P0340 or P0341 also
set?

—

Go to Applicable 

DTC

Go to Step 3

3

Inspect the engine mechanical timing. Refer to the
Engine Mechanical section. Repair as necessary.

Notice:
If the flywheel dowel pin is missing or pushed in
and the flywheel is incorrectly installed, this DTC
may set.

Did you complete the repair?

—

Go to Step 4

—

4

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. If engine does not start,
crank over the engine for 10 seconds.

Did the DTC fail this ignition?

—

Go to Step 2

Go to Step 5