Isuzu KB P190. Manual - part 598

6E–222

ENGINE DRIVEABILITY AND EMISSIONS

DIAGNOSTIC TROUBLE CODE (DTC) P1631 

IMMOBILIZER WRONG SIGNAL

Condition for setting the DTC and action taken when the DTC sets

Circuit Description

The ECM decides whether that is an abnomality in the
immobilizer control system. DTC P1631 is recorded by
the ECM when received response was not correct.

Diagnostic Aids

Check for the following conditions:

• Poor connection at ECM and Immobilizer-Inspect

harness connectors for backed out terminals,
improper mating, broken locks, improperly formed or

damaged terminals, and poor terminal to wire
connection.

• Damaged harness-Inspect the wiring harness for

damage, If the harness appears to be OK, disconnect
the ECM and Immobilizer, turn the ignition “ON” and
observe a voltmeter connected to the suspect driver
circuit at the ECM and Immobilizer harnass connector
while moving connectors and wiring harnesses
relates to the MIL. A change in voltage will indicate
the location of the fault.

Code

Type

DTC Name

DTC Setting Condition

Fail-Safe (Back Up)

P1631

-

Immobilizer Wrong Signal

Received response is not correct.

1. Engine does not start. 
2. Check engine lamp flash.

ENGINE DRIVEABILITY AND EMISSIONS

6E–223

Diagnostic Trouble Code (DTC) P1631 Immobilizer Wrong Signal

Step

Action

Value(s)

Yes

No

1

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go  to  Step 2

Go to On Board 

Diagnostic 

(OBD) System 

Check

2

1. Connect the Tech 2. 

2. Review and record the failure information. 

3. Select “F0: Read DTC Infor By Priority” in “F0:

Diagnostic Trouble Code”. 

Is the DTC P1631 stored as “Present Failure”?

—

Go to Step 3

Refer to 

Diagnostic Aids 

and Go to Step 

3

3

1. Using the Tech2, ignition “On” and engine “Off”. 

2. Select “Clear DTC Information” with the Tech2 and

clear the DTC information. 

3. Operate the vehicle and monitor the “F5: Failed

This Ignition” in “F2: DTC Information”.

Was the DTC P1631 stored in this ignition cycle?

—

Go to Step 4

Refer to 

Diagnostic Aids 

and Go to Step 

4

4

1. Using the Tech 2, ignition “On” and engine “Off”. 

2. Select “Immobilizer” in the system selection menu

“Body”. 

3. Select “Read DTC Info Ordered By Priority” in the

“Diagnositic Trouble Code”. 

Was the DTC B0007 stored in this ignition cycle?

—

Refer to 

“Immobilizer 

Workshop 

Manual” & Go 

to DTC Chart 

B0007 

Go to Step 5

5

Is the ECM programmed with the latest software
release? 
If not, download the latest software to the ECM using
the “SPS (Service Programming System)”. 
Was the problem solved?

—

Verify repair

Go to Step 6

6

Replace the ECM. 
Is the action complete? 
IMPORTANT:  The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual. 
Following ECM programming, the immobilizer system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobilizer System-ECM replacement” for
the ECM/Immobilizer linking procedure.

—

Verify repair

—

6E–224

ENGINE DRIVEABILITY AND EMISSIONS

DIAGNOSTIC TROUBLE CODE (DTC) P1648 

WRONG SECURITY CODE ENTERED

Condition for setting the DTC and action taken when the DTC sets

Circuit Description

The ECM decides whether that is an abnomality in the
immobilizer control system. DTC P1648 is recorded by
the ECM when received incorrect security code.

Diagnostic Aids

Check for the following conditions:

• Poor connection at ECM and Immobilizer-Inspect

harness connectors for backed out terminals,
improper mating, broken locks, improperly formed or

damaged terminals, and poor terminal to wire
connection.

• Damaged harness Inspect the wiring harness for

damage, If the harness appears to be OK, disconnect
the ECM and Immobilizer, turn the ignition “ON” and
observe a voltmeter connected to the suspect driver
circuit at the ECM and Immobilizer harnass connector
while moving connectors and wiring harnesses
relates to the MIL. A change in voltage will indicate
the location of the fault.

Code

Type

DTC Name

DTC Setting Condition

Fail-Safe (Back Up)

P1648

-

Wrong Security Code Entered

Received incorrect security code.

1. Engine does not start. 
2. Check engine lamp flash.

ENGINE DRIVEABILITY AND EMISSIONS

6E–225

Diagnostic Trouble Code (DTC) P1648 Wrong Security Code Entered

Step

Action

Value(s)

Yes

No

1

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go  to  Step 2

Go to On Board 

Diagnostic 

(OBD) System 

Check

2

1. Connect the Tech 2. 

2. Review and record the failure information. 

3. Select “F0: Read DTC Infor By Priority” in “F0:

Diagnostic Trouble Code”. 

Is the DTC P1648 stored as “Present Failure”?

—

Go to Step 3

Refer to 

Diagnostic Aids 

and Go to Step 

3

3

1. Using the Tech2, ignition “On” and engine “Off”. 

2. Select “Clear DTC Information” with the Tech2 and

clear the DTC information. 

3. Operate the vehicle and monitor the “F5: Failed

This Ignition” in “F2: DTC Information”.

Was the DTC P1648 stored in this ignition cycle?

—

Go to Step 4

Refer to 

Diagnostic Aids 

and Go to Step 

4

4

1. Using the Tech 2, ignition “On” and engine “Off”. 

2. Select “Immobilizer” in the system selection menu

“Body”. 

3. Select “Read DTC Info Ordered By Priority” in the

“Diagnositic Trouble Code”. 

Was the DTC B0007 stored in this ignition cycle?

—

Refer to 

“Immobilizer 

Workshop 

Manual” & Go 

to DTC Chart 

B0007 

Go to Step 5

5

Is the ECM programmed with the latest software
release? 
If not, download the latest software to the ECM using
the “SPS (Service Programming System)”. 
Was the problem solved?

—

Verify repair

Go to Step 6

6

Replace the ECM. 
Is the action complete? 
IMPORTANT:  The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual. 
Following ECM programming, the immobilizer system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobilizer System-ECM replacement” for
the ECM/Immobilizer linking procedure.

—

Verify repair

—