Isuzu KB P190. Service manual — part 315

6E-226 Engine Control System (4JH1)

DTC P1630 (Symptom Code A, B) (Flash Code 51)

Circuit Description
The engine control module (ECM) calculates the
desired fuel injection quantity and timing using data sent
from various sensors. These desired data are sent to
the fuel injection pump control unit (PCU) via a
controller area network (CAN) communication bus. The
PCU also receives signals from the internal inputs:
pump camshaft position (CMP) sensor that is located
inside the fuel injection pump to determine the cam ring
rotation angle and the fuel injection pump speed. The
fuel temperature (FT) sensor is internal the PCU. These
values are used to compare the desired values sent
from the ECM then PCU determines the injection timer
piston position and fuel injection quantity, and actuates
timing control valve (TCV) & fuel injection solenoid
valve based on control maps in the PCU.
The fuel injection solenoid valve is installed to the fuel
injection pump rear side. The fuel injection event is
determined by this solenoid ON/OFF command. The
fuel injection solenoid valve cuts the fuel when the
engine shutoff (ESO) solenoid valve is commanded
shutoff from the PCU. (The fuel injection solenoid valve
and engine shutoff (ESO) solenoid valve is same part. It
calls ESO solenoid valve when fuel is shutoff.) When
the ignition switch is turned OFF or commanded from
fail-safe action, the ESO solenoid valve is commanded
shutoff to stop the engine running. If the ECM detects
that the fuel injection solenoid valve control current
problem, this DTC will set.

Condition for Setting the DTC

• The ECM detects that the PCU monitored fuel

injection solenoid valve control current is too high.
(Symptom Code A)

• The ECM detects that the PCU continuously flow

the control current to the fuel injection solenoid
valve. (Symptom Code B)

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM limits fuel injection quantity. (Symptom

Code A)

• The ECM cuts fuel injection. (Symptom Code B)

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 scan tool.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Notice:

• Fuel injection solenoid valve is internal to the fuel

injection pump assembly.

• PCU is part of the fuel injection pump assembly.

DTC P1630 (Symptom Code A, B) (Flash Code 51)

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 scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the Diagnostic Trouble Code (DTC)

Information with the scan tool.

Does the DTC fail this ignition?



Go to Step 3

Go to Step 4

3

Important: The fuel injection pump must be timed to
the engine.
Replace the fuel injection pump. Refer to Fuel
Injection Pump Replacement in engine mechanical
section.
Did you complete the replacement?



Go to Step 4



4

1. Clear the DTCs with the scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the DTC Information with the scan tool.
Did the DTC fail this ignition?



Go to Step 3

Go to Step 5

5

Observe the DTC Information with the scan tool.
Are there any DTCs that you have not diagnosed?



Go to Diagnostic

Trouble Code (DTC)

List System

OK

Engine Control System (4JH1) 6E-227

DTC P1650 (Symptom Code A) (Flash Code 44)

Circuit Description
The engine control module (ECM) calculates the
desired fuel injection quantity and timing using data sent
from various sensors. These desired data are sent to
the fuel injection pump control unit (PCU) via a
controller area network (CAN) communication bus. The
PCU also receives signals from the internal inputs:
pump camshaft position (CMP) sensor that is located
inside the fuel injection pump to determine the cam ring
rotation angle and the fuel injection pump speed. The
fuel temperature (FT) sensor is internal the PCU. These
values are used to compare the desired values sent
from the ECM then PCU determines the injection timer
piston position and fuel injection quantity, and actuates
timing control valve (TCV) & fuel injection solenoid
valve based on control maps in the PCU.
The ECM monitors CAN operational status by expecting
a constant flow of messages from the PCU. If the ECM
detects that the PCU receives from the CAN controller
rest or Bus Offline, this DTC will set.
Condition for Setting the DTC

• The ECM detects that the PCU receives from the

CAN controller reset or Bus Offline.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM cuts the 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 scan tool.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

DTC P1650 (Symptom Code A) (Flash Code 44)
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 scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Monitor the Diagnostic Trouble Code (DTC)

Information with the scan tool.

Is DTC P1651 (Symptom Code A or B) set?



Go to Applicable

DTC

Go to Step 3

3

Monitor the DTC Information with the scan tool.
Does the DTC fail this ignition?



Go to Step 4

Go to Diagnostic

Aids

4

1. Turn OFF the ignition.
2. Disconnect the fuel injection pump control unit

(PCU) harness connector.

3. Connect a DMM across the controller area

network (CAN) harness (pins 1 and 2 of E-6
connector).

4. Measure the resistance across the CAN

terminals.

Is the resistance within the specified value?

110-130Ω

Go to Step 5

Go to Step 10

5

1. Connect a DMM between the CAN Low signal

circuit (pin 1 of E-6 connector) and a known good
ground.

2. Turn ON the ignition, with the engine OFF.
Is the DMM voltage within the specified value?

1.5 – 2.5 volts

Go to Step 6

Go to Step 11

6

1. Keep the ignition switch ON, with the engine

OFF.

2. Connect a DMM between the CAN High signal

circuit (pin 2 of E-6 connector) and a known good
ground.

Is the DMM voltage within the specified value?

3.0 – 4.0 volts

Go to Step 7

Go to Step 12

6E-228 Engine Control System (4JH1)

Step Action

Value(s)

Yes

No

7

1. Turn OFF the ignition.
2. Reconnect the PCU harness connector.
3. Disconnect the engine control module (ECM) C-

57 harness connector. Keep the ECM C-56
harness connector with connected.

4. Connect a DMM across the CAN harness (pins

99 and 100 of C-57 connector).

5. Measure the resistance across the CAN

terminals.

Is the resistance within the specified value?

110-130Ω

Go to Step 8

Go to Step 14

8

1. Connect a DMM between the CAN Low signal

circuit of the ECM harness (pin 99 of C-57
connector) and a known good ground.

2. Turn ON the ignition, with the engine OFF.
Is the DMM voltage within the specified value?

1.5 – 2.5 volts

Go to Step 9

Go to Step 16

9

1. Keep the ignition switch ON, with the engine

OFF.

2. Connect a DMM between the CAN High signal

circuit of the ECM harness (pin 100 of C-57
connector) and a known good ground.

Is the DMM voltage within the specified value?

3.0 – 4.0 volts

Go to Step 13

Go to Step 16

10

1. Test the CAN Low and High circuit between the

ECM (pins 99 and 100 of C-57 connector) and
the PCU (pins 1 and 2 of E-6 connector) for the
following conditions:

• An open circuit
• A short each other
• High

resistance.

2. Repair the circuit(s) as necessary.
Did you find and correct the condition?



Go to Step 18

Go to Step 15

11

1. Test the CAN Low circuit between the ECM (pin

99 of C-57 connector) and the PCU (pin 1 of E-9
connector) for the following conditions:

• A short to ground
• A short to battery or ignition voltage

2. Repair the circuit(s) as necessary.
Did you find and correct the condition?



Go to Step 18

Go to Step 17

12

1. Test the CAN Low circuit between the ECM (pin

100 of C-57 connector) and the PCU (pin 2 of E-
9 connector) for the following conditions:

• A short to ground
• A short to battery or ignition voltage

2. Repair the circuit(s) as necessary.
Did you find and correct the condition?



Go to Step 18

Go to Step 17

13

1. Reconnect all previously disconnected harness

connector(s).

2. Clear the DTCs with the scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Turn ON the ignition, with the engine OFF.
5. Monitor the DTC Information with the scan tool.
Is DTC P0251 (Symptom Code E) set?



Go to Step 16

Go to Diagnostic

Aids

Engine Control System (4JH1) 6E-229

Step Action

Value(s)

Yes

No

14

1. Turn OFF the ignition.
2. Disconnect the PCU harness connector.
3. Inspect for an intermittent and for poor

connections at the harness connector of the PCU
(pins 1 and 2 of E-6 connector).

4. Repair the connection(s) as necessary.
Did you find and correct the condition?



Go to Step 18

Go to Step 16

15

1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for poor

connections on the CAN Low or High circuits at
the harness connector of the ECM (pins 99 and
100 of C-57 connector).

4. Repair the connection(s) as necessary.
Did you find and correct the condition?



Go to Step 18

Go to Step 17

16

Important: The fuel injection pump must be timed to
the engine.
Replace the fuel injection pump. Refer to Fuel
Injection Pump Replacement in engine mechanical
section. (PCU is part of the fuel injection pump
assembly)
Did you complete the replacement?



Go to Step 18



17

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 18



18

1. Reconnect all previously disconnected harness

connector(s).

2. Clear the DTCs with the scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Monitor the DTC Information with the scan tool.
Does the DTC fail this ignition?



Go to Step 2

Go to Step 19

19

Observe the DTC Information with the scan tool.
Are there any DTCs that you have not diagnosed?



Go to Diagnostic

Trouble Code (DTC)

List System

OK