Isuzu KB P190. Manual - part 464

 

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Isuzu KB P190. Manual - part 464

 

 

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-239

DTC P124B (Flash Code 157)

Circuit Description

The ECM calculates the optimum fuel injection ON time
using data sent from various engine sensors. The
common 1 and common 2 fuel injector charge voltage
circuit is a high-voltage supply which drives fuel
injectors for each cylinder in conjunction with the ECM
grounding the fuel injector solenoid control circuit. If the
fuel injector charge voltage circuit or solenoid control
circuit is shorted across the bank, this DTC will set.

Condition for Running the DTC

• The battery voltage is more than 9 volts.

• The ignition switch is ON.

• The engine speed is lower than 2000RPM.

Condition for Setting the DTC

• The ECM detects that the fuel injector charge

voltage circuit or solenoid control circuit is shorted
across the bank.

Action Taken When the DTC Sets

• The ECM illuminates the SVS lamp when the

diagnostic runs and fails. Refer to DTC Type
Definitions for Action Taken When the DTC Sets -
Type C. (Euro 4 Specification)

• The ECM illuminates the MIL when the diagnostic

runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
(Except Euro 4 Specification)

Condition for Clearing the DTC

• Refer to DTC Type Definitions for Condition for

Clearing the SVS Lamp/ DTC - Type C. (Euro 4
Specification)

• Refer to DTC Type Definitions for Condition for

Clearing the MIL/ DTC - Type A. (Except Euro 4
Specification)

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views

Circuit/ System Testing DTC P124B

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 a scan tool.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

Monitor the DTC Information with a scan tool.

Does the DTC fail this ignition?

—

Go to Step 3

Go to Diagnostic 

Aids

6E-240   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

3

1.

Turn OFF the ignition.

2.

Disconnect all fuel injector harness
connectors.

3.

Disconnect the ECM harness connector.

4.

Measure continuity through the fuel injector
harness connectors.

• #1 and #2 solenoid control circuits (pin 1

of E-13 and pin 1 of E-14)

• #1 and #2 charge voltage circuits (pin 2

of E-13 and pin 2 of E-14)

• #1 solenoid control circuit (pin 1 of E-13)

and #2 charge voltage circuit (pin 2 of E-
14)

• #2 solenoid control circuit (pin 1 of E-14)

and #1 charge voltage circuit (pin 2 of E-
13)

• #1 and #3 solenoid control circuits (pin 1

of E-13 and pin 1 of E-15)

• #1 and #3 charge voltage circuits (pin 2

of E-13 and pin 2 of E-15)

• #1 solenoid control circuit (pin 1 of E-13)

and #3 charge voltage circuit (pin 2 of E-
15)

• #3 solenoid control circuit (pin 1 of E-15)

and #1 charge voltage circuit (pin 2 of E-
13)

• #2 and #4 solenoid control circuits (pin 1

of E-14 and pin 1 of E-16)

• #2 and #4 charge voltage circuits (2 of E-

14 and pin 2 of E-16)

• #2 solenoid control circuit (pin 1 of E-14)

and #4 charge voltage circuit (pin 2 of E-
16)

• #4 solenoid control circuit (pin 1 of E-16)

and #2 charge voltage circuit (pin 2 of E-
14)

• #3 and #4 solenoid control circuits (pin 1

of E-15 and pin 1 of E-16)

• #3 and #4 charge voltage circuits (pin 2

and of E-15 and pin 2 of E-16)

• #3 solenoid control circuit (pin 1 of E-15)

and #4 charge voltage circuit (pin 2 of E-
16)

• #4 solenoid control circuit (pin 1 of E-16)

and #3 charge voltage circuit (pin 2 of E-
15)

5.

Repair the short circuit if continuity exists for
any measurement.

Did you find and correct the condition?

—

Go to Step 5

Go to Step 4

4

Important: Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.

Did you complete the replacement?

—

Go to Step 5

—

Step

Action

Value(s)

Yes

No

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-241

5

1.

Reconnect all previously disconnected
harness connector(s).

2.

Clear the DTCs with a scan tool.

3.

Turn OFF the ignition for 30 seconds.

4.

Start the engine.

5.

Operate the vehicle within the Conditions for
Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/ Failure
Records.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 6

6

Observe the DTC Information with a scan tool.

Are there any DTCs that you have not diagnosed?

—

Go to DTC List

System OK

Step

Action

Value(s)

Yes

No

6E-242   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

DTC P1261 (Flash Code 34)

Circuit Description

The charge up circuit in the ECM steps up the voltage
for fuel injectors and is divided into two banks, common
1 and common 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 1 fuel injector charge up circuit in the
ECM is an insufficient charge or an overcharge, this
DTC will set. (Charge Up Voltage DTC)
If the supply voltage to the common 1 and common 2
fuel injector charge up circuits is an excessively low or
high voltage, this DTC will also set. (Supply Voltage
Low or High DTC)

Condition for Running the DTC

Charge Up Voltage DTC

• The battery voltage is more than 9 volts.

• The ignition switch is ON.

• The engine is not running.

Supply Voltage Low or High DTC

• The battery voltage is more than 9 volts.

• The ignition switch is ON.

Condition for Setting the DTC

Charge Up Voltage DTC

• The ECM detects that the common 1 fuel injector

charge up circuit is an insufficient charge or an
overcharge.

Supply Voltage Low or High DTC

• The ECM detects that the supply voltage to the

common 1 and common 2 fuel injector charge up
circuits is an excessively low or high voltage.

Action Taken When the DTC Sets

Charge Up Voltage DTC & Supply Voltage Low DTC

• The ECM illuminates the MIL when the diagnostic

runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.

• The ECM limits fuel injection quantity.

• The ECM inhibits cruise control.

Supply Voltage High DTC

• The ECM illuminates the SVS lamp when the

diagnostic runs and fails. Refer to DTC Type
Definitions for Action Taken When the DTC Sets -
Type C. (Euro 4 Specification)

• The ECM illuminates the MIL when the diagnostic

runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
(Except Euro 4 Specification)

• The ECM limits fuel injection quantity.

• The ECM inhibits cruise control.

Condition for Clearing the DTC

Charge Up Voltage DTC & Supply Voltage Low DTC

• Refer to DTC Type Definitions for Condition for

Clearing the MIL/ DTC - Type A

Supply Voltage High DTC

• Refer to DTC Type Definitions for Condition for

Clearing the SVS Lamp/ DTC - Type C. (Euro 4
Specification)

• Refer to DTC Type Definitions for Condition for

Clearing the MIL/ DTC - Type A. (Except Euro 4
Specification)

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views

Circuit/ System Testing DTC P1261

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 a scan tool.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

Monitor the DTC Information with a scan tool.

Does the DTC fail this ignition?

—

Go to Step 3

Go to Step 8

 

 

 

 

 

 

 

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