Isuzu KB P190. Manual - part 468

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-255

DTC P1621 (Flash Code 54, 254)

Circuit Description

The electrically erasable & programmable read only
memory (EEPROM) memorizes learning data, VIN data
and immobilzer security information. If the ECM detects
an error in either of their data, this DTC will set.

Condition for Running the DTC

• The ignition switch is ON.

Condition for Setting the DTC

Either of following condition is met:

• The ECM detects a faulty learning data in its

internal EEPROM. (Flash Code 54)

• The ECM detects a faulty VIN data or immobilizer

security information in its internal EEPROM. (Flash
Code 254)

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. (Flash Code

54)

• The ECM inhibits cruise control. (Flash Code 54)

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)

Circuit/ System Testing DTC P1621

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.

Ensure that all tool connections are secure.

2.

Ensure that programming equipment is
operating correctly.

3.

Install a scan tool.

4.

Turn OFF the ignition for 30 seconds.

5.

Turn ON the ignition, with the engine OFF.

6.

Monitor the DTC Information with a scan tool.

Does the DTC fail this ignition?

—

Go to Step 3

Go to Step 5

3

1.

Verify the correct VIN and immobilizer code
are entered into the ECM with a scan tool.
Refer to ECM Replacement.

2.

Turn OFF the ignition for 30 seconds.

3.

Turn ON the ignition, with the engine OFF.

Does the DTC fail this ignition?

—

Go to Step 4

Go to Step 5

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

—

6E-256   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

5

1.

Clear the DTCs with a scan tool.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

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 2

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

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-257

DTC P1664 (Flash Code 76)

Circuit Description

The service vehicle soon (SVS) lamp is located on the
instrument panel (IP) cluster. The SVS lamp informs
the driver that a non-emission related fault has
occurred and vehicle service required.
The ECM monitors the SVS lamp control circuit for
conditions that are incorrect for the commanded state
of the SVS lamp. For example, a failure condition exists
if the ECM detects low voltage when the SVS lamp is
commanded OFF, or high voltage when the SVS lamp
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

Low Voltage DTC

• The ECM detects a low voltage condition on the

SVS lamp control circuit when the lamp is
commanded OFF.

High Voltage DTC

• The ECM detects a high voltage condition on the

SVS lamp control circuit when the lamp is
commanded ON.

Action Taken When the DTC Sets

Low Voltage DTC

• The ECM will not illuminate the MIL or SVS lamp.

• Refer to DTC Type Definitions for Action Taken

When the DTC Sets - Type D.

High Voltage 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.

Condition for Clearing the DTC

Low Voltage DTC

• Refer to DTC Type Definitions for Condition for

Clearing the DTC - Type D.

High Voltage DTC

• Refer to DTC Type Definitions for Condition for

Clearing the SVS Lamp/ DTC - Type C.

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 P1664

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 Service Vehicle Soon (SVS)
Lamp Control with a scan tool.

4.

Command the lamp ON and OFF.

Does the SVS lamp 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

—

6E-258   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

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 SVS lamp OFF?

—

Go to Sep 6

Go to Step 12

6

1.

Remove the Meter (10A) fuse that supplies
voltage to the SVS lamp.

2.

Turn ON the ignition, with the engine OFF.

3.

Measure the voltage from the SVS lamp
control circuit in the ECM harness connector
(pin 71 of C-58) to a known good ground.

Is the voltage less than the specified value?

1 volt

Go to Step 7

Go to Step 13

7

1.

Turn OFF the ignition.

2.

Reinstall the Meter (10A) fuse.

3.

Turn ON the ignition, with the engine OFF.

4.

Connect a 3-amp fused jumper wire between
the ECM harness connector (pin 71 of C-58)
and a known good ground.

Is the SVS lamp illuminated?

—

Go to Step 11

Go to Step 8

8

1.

Turn OFF the ignition.

2.

Remove the IP cluster.

3.

Connect a test lamp between the ignition
voltage feed circuit of the IP cluster harness
connector (pin 8 of B-24) and a known good
ground.

4.

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

—

Go to Step 9

Go to Step 14

9

1.

Test the control circuit between the ECM (pin
71 of C-58) and the IP cluster (pin 26 of B-23)
for an open circuit or high resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 17

Go to Step 10

10

1.

Inspect for an intermittent and for poor
connections at the harness connector of the
IP cluster (pin 8 of B-24 and pin 26 of B-23).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 17

Go to Step 15

11

1.

Inspect for an intermittent and for a poor
connection at the harness connector of the
ECM (pin 71 of C-58).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 17

Go to Step 16

12

Repair the short to ground between the ECM (pin
71 of C-58) and the IP cluster (pin 26 of B-23).

Did you complete the repair?

—

Go to Step 17

—

13

Repair the short to battery or ignition voltage
between the ECM (pin 71 of C-58) and the IP
cluster (pin 26 of B-23).

Did you complete the repair?

—

Go to Step 17

—

Step

Action

Value(s)

Yes

No