Isuzu KB P190. Manual - part 455

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-203

DTC P0642 or P0643 (Flash Code 55)

Circuit Description

The ECM provides 5 volts reference voltage through
the reference circuit 1 to the accelerator pedal position
(APP) sensor 1. The ECM monitors the voltage on the
5 volts reference circuit 1. If the ECM detects the
voltage is excessively low or high, DTC P0642 or
P0643 will set.

Condition for Running the DTC

• The battery voltage is more than 6 volts.

• The ignition switch is ON.

Condition for Setting the DTC

• The ECM detects that the 5 volts reference circuit

1 voltage is less than 4.7 volts. (DTC P0642)

• The ECM detects that the 5 volts reference circuit

1 voltage is more than 5.3 volts. (DTC P0643)

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)

• The ECM limits fuel injection quantity

• The ECM inhibits cruise control.

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 P0642

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

3

1.

Turn OFF the ignition.

2.

Disconnect the accelerator pedal position
(APP) sensor harness connector.

3.

Connect a DMM between the 5 volts reference
circuit (pin 10 of C-40) and a known good
ground.

4.

Turn ON the ignition, with engine OFF.

Is the DMM voltage more than the specified value?

4.7 volts

Go to Step 5

Go to Step 4

4

1.

Test the 5 volts reference circuit between the
ECM (pin 11 of C-58) and the APP sensor (pin
10 of C-40) for the following conditions:

• A short to ground

• A short to the low reference circuit

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 7

Go to Step 6

6E-204   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Circuit/ System Testing DTC P0643

5

Replace the APP sensor. Refer to APP Sensor
Replacement.

Did you complete the replacement?

—

Go to Step 7

—

6

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

Did you complete the replacement?

—

Go to Step 7

—

7

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 8

8

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

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

3

1.

Test the 5 volts reference circuit between the
ECM (pin 11 of C-58) and the APP sensor 1
(pin 10 of C-40) 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 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

—

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-205

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-206   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

DTC P0650 (Flash Code 77)

Circuit Description

The malfunction indicator lamp (MIL) is located on the
instrument panel (IP) cluster. The MIL informs the
driver that an emission system fault has occurred and
that the engine control system requires service.
The ECM monitors the MIL control circuit for conditions
that are incorrect for the commanded state of the MIL.
For example, a failure condition exists if the ECM
detects low voltage when the MIL is commanded OFF,
or high voltage when the MIL is commanded ON. If the
ECM detects an improper voltage level on the control
circuit, this DTC will set.

Condition for Running the DTC

• The ignition voltage is more than 9 volts.

• The ignition switch is ON.

Condition for Setting the DTC

Either of following condition is met:

• The ECM detects a low voltage condition on the

MIL control circuit when the lamp is commanded
OFF.

• The ECM detects a high voltage condition on the

MIL control circuit when the lamp is commanded
ON.

Action Taken When the DTC Sets

• 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.

Condition for Clearing the DTC

• Refer to DTC Type Definitions for Condition for

Clearing the MIL/ DTC - Type A.

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 P0650

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.

Verify whether the instrument panel (IP)
cluster is operational.

2.

Install a scan tool.

3.

Perform the Malfunction Indicator Lamp (MIL)
Control with a scan tool.

4.

Command the lamp ON and OFF.

Does the MIL turn ON and OFF with each
command?

—

Go to Diagnostic 

Aids

Go to Step 3

3

1.

Turn OFF the ignition.

2.

Inspect the Meter (10A) fuse in the cabin fuse
block.

Is the Meter (10A) fuse open?

—

Go to Step 4

Go to Step 5

4

Replace the Meter (10A) fuse. If the fuse continues
to open, repair the short to ground on one of the
circuits that is fed by the Meter (10A) fuse or
replace the shorted attached component.

Did you complete the repair?

—

Go to Step 17

—

5

1.

Turn OFF the ignition.

2.

Disconnect the ECM J-2 (C-58) harness
connector.

3.

Turn ON the ignition, with the engine OFF.

Is the MIL OFF?

—

Go to Sep 6

Go to Step 12