2004 ISUZU TF SERIES engine

IMMOBILIZER SYSTEM 11A-31

Diagnostic procedure


Once the cause of DTC is repaired or gone,
engine can be operated normally, and present
DTC becomes history code.


History code is canceled by no repeat failure on 25
consequence ignition key on afterward.


History code cannot be canceled by batter
y
connector disconnected.
Clearing Diagnostic Trouble Codes
IMPORTANT:
Do not clear DTCs unless directed to do
so by the service information provided for each
diagnostic procedure. When DTCs are cleared, the
Failure Record data which may help diagnose an
intermittent fault will also be erased from memory.
Verifying Vehicle Repair
Verification of vehicle repair will be more
comprehensive for vehicles with immobilizer system
diagnostic. Following a repair, the technician should
perform the following steps:
1.
Review and record the Fail Records for the DTC
which has been diagnosed.
2.
Clear DTC(s).
3.
Operate the vehicle within conditions noted in the
Fail Records.
4.
Monitor the DTC status information for the DTC
which has been diagnosed until the diagnostic test
associated with that DTC runs.
Following these steps are very important in verifying
repairs on immobilizer systems. Failure to follow these
steps could result in unnecessary repairs.
Diagnostic Aids
Check the condition for system parts.



Installation condition, poor connection, damage,
system parts malfunction. Harness, Fuse, Relay,
Immobilizer coil (antenna), Key, Meter, Immobilize
r
control unit (ICU), Engine control module (ECM).
NOE: Breakage of immobilizer fuse does not operate
immobilizer system. Check engine lamp flashes at this
time.

Check the Electro-Magnetic Interference (EMI)



Location of vehicle check

Move the vehicle to a new location and perform
the check again.


Non-OEM Parts.

Switch is "OFF" or remove the Non-OEM parts and
perform the check again.


Other

Remove the accessory and another key from key.

Check the other items.



Battery voltage is low.


Immobilizer programming functions.

Must be programmed immobilizer system.


Registration for security code, immobilizer control
unit parts number.


Key switch operation.

Immobilizer system may detect a history DTC b
y
the timing of ON-OFF of a key switch.


Active the immobilizer system.


Keyless entry system is malfunction.


Anti theft system is malfunction.

Check the operation

Check the operation "Lock / unlock" by using transmitte
r
(key) on the vehicle.

11A-32 IMMOBILIZER SYSTEM

Diagnostic Trouble Code (DTC) list with ECM





Immobilizer Control Unit (ICU)
DTC
Description Note
B0001
REPLACE ELECTRONIC CONTROL UNIT
(ECU) (IMMOBILIZER FAULT) This error code appears if a RAM /ROM Error was
detected or the EEPROM is defect.
B0002 IMMOBILIZER NOT PROGRAMMED Immobilizer control unit is not programmed.
B0003 TRANSPONDER KEY PROBLEM

Reading of Transponder information failed with ignition
on transponder has a fault.


Hardware fault in reading circuit.
B0004
IMMOBILIZER COIL CIRCUIT (ANTENNA
COIL FAULT) Immobilizer coil has a fault.
B0005 COMMUNICATION LINE W VOLTAGE LOW Short circuit to ground or open circuit.
B0006 COMMUNICATION LINE W VOLTAGE HIGH Short circuit to 12V.
B0007 NO ENGINE REQUEST RECEIVED No ECM Challenge.
B0008 WRONG TRANSPONDER KEY Incorrect security code response received.
B0009 NO TRANSPONDER KEY PROGRAMMED Transponder security code table empty
B0010 UNKNOWN TRANSPONDER KEY Transponder security code not valid.






Engine Control Module (ECM: Gasoline Engine {6VE1, C24SE})

DTC Description
Note
P1626 No Response From Immobilizer Refer to Engine Control system section
P1631 Received Response Was Not Correct Refer to Engine Control system section
P1648 Received Incorrect Security Code Refer to Engine Control system section
P1649 Security Code & Security Key Not
Programmed Refer to Engine Control system section






Engine Control Module (ECM: Diesel Engine {4JH1-TC, 4JA1-TC})

DTC Description Note
P1610 Seeds and Key File Destroyed Refer to Engine Control system section
P1611 Wrong Security Code Entered Refer to Engine Control system section
P1612/
P1613 Immobilizer No or Wrong Signal Refer to Engine Control system section
P1649 Wrong Transponder Key Refer to Engine Control system section

IMMOBILIZER SYSTEM 11A-33

Diagnostic Trouble Code (DTC) list with Engine Immobilizer Unit (4JA1-T Diesel Engine)





Engine Immobilizer Unit
Code
(DTC) Description Detecting Condition
B0011 TRANSPONDER KEY PROBLEM Transponder code unsuccessfully read 5 consecutive
time. (No completely read in 500ms transponder code)
B0012 WRONG TRANSPONDER KEY Immobilizer program no executed.
B0013 IMMOBILIZER NOT PROGRAMMED Processing program no executed.
B0014 NO TRANSPONDER KEY PROGRAMMED Processing to save the transponder key in the control unit
not Executed.
B0015 FREQUENCY SIGNAL Lo Lo level (less than 2.5) input during the Hi level was being
output to the communication line.
B0016 FREQUENCY SIGNAL Hi (Diesel) Hi level (more than 2.5v) input during the Lo level was
being output to the communication line.
B0023 ANTENNA COIL OPEN Antenna coil not connected.
B0024 WRONG TRANSPONDER RESPONSE Transponder response signal with challenge is wrong.
B0055 EEPROM ERROR Write and read cannot be correctly made to and from the
EEPROM in the control unit.

11A-34 IMMOBILIZER SYSTEM

IMMOBILIZER SYSTEM CHECK
Step Action Value(s) Yes No
1 1. Key position is "ON," engine "OFF."
2. Observe the check engine lamp.
Note: When a key switch is turned ON, check engine
lamp will turn on and a check engine lamp will be
turned off after a few seconds.
Is the check engine lamp "ON"? 
Go to Step 2
Go to "No
Immobilizer
warning lamp"
2 1. Key position is "ON," engine "OFF."
2. Observe the check engine lamp.
Note: When a key switch is turned ON, check engine
lamp will turn on and a check engine lamp will be
turned off after a few seconds.
Is the check engine lamp "OFF"?
(Check engine lamp does not flash) 
Go to Step 3
Go to
"Immobilizer
warning lamp on
steady"
3 1. Key position is "OFF."
2. Install a scan tool.
3. Key position is "ON."
4. Attempt to display immobilizer data with the scan
tool.
Does the scan tool display immobilizer data? 
Go to Step 9
Go to Step 4
4 1. Key position is "OFF," disconnect the immobilizer
control unit (ICU).
2. Check the DLC (Data Link Connector) circuit for
an open, short to ground, or short to voltage.
Also, check the DLC ignition feed circuit for an
open or short to ground and the DLC ground
circuit for an open.
Was a problem found? 
Go to Step 5
Go to Step 6
5 Repair or replace the DLC (Data Link Connector)
circuit.
Was the action complete? 
Go to Step 3 
6
1. Check the ICU circuit for an open, short to ground,
or short to voltage. Also, check the ICU ignition
feed circuit for an open or short to ground and the
ICU ground circuit for an open.
2. If a problem is found, repair as necessary.
Was a problem found? 
Go to Step 7
Go to Step 8
7 Repair or replace the ICU ignition feed and ground
circuits.
Was the action complete? 
Go to Step 3 
8 Replace the immobilizer control unit (ICU).
IMPORTANT:
The replacement ICU must be
programmed the immobilizer data by the scan tool.
Was the action complete? 
Go to Step 3 
9 Select "Display DTCs" with the scan tool.
Are any DTCs stored? 
Go to Step 10
Go to Step 13

IMMOBILIZER SYSTEM 11A-35

Step Action Value(s) Yes No
10 Review and record for scan tool Failure Records data
and DTCs.
Was the action complete? 
Go to Step 11 
11 Following the DTC is stored.
Are there DTC B0001 or B0055 stored?
Go to applicable
DTC table after
Go to Step 12 Go to Step 12
12 Clear the DTCs by "Clear the Information "with scan
tool.
Did the DTCs Cleared? 
Go to Step 12 
13 Select "Display DTCs" with the scan tool.
Are any DTCs stored? 
Go to applicable
DTC table Go to Step 14
14 1. Key position is "ON," engine "OFF."
2. Observe the check engine lamp.
Note: If a key switch is turned ON, check engine lamp
will turn on and a check engine lamp will be turned off
after a few seconds.
Is the check engine lamp "flash"? 
Go to Step 15
Go to Step 20
15 Check the engine control system.
If a problem is found, repair as necessary.
(Refer to section 6E: system check and DTCs)
IMPORTANT:
The replacement ECM must be
programmed the immobilizer data by scan tool.
(Except 4JA1-L Engine)
Was the action complete? 
Go to Step 16 
16 Check the key.
Is a key peculiar to a vehicle? 
Go to Step 18
Go to Step 17
17 Change into a peculiar key.
IMPORTANT:
If replace the key,
after replace lock
cylinders, perform the following below the items.

Replace the keys and key cylinders.

Program the immobilizer system.
(Refer to "Important information on Programming")
Was the action complete? 
Go to Step 18 
18 Check the immobilizer programming functions.


Immobilizer control unit (ICU).


Engine control module (ECM).


Transponder (Key).
If a problem is found, repair as necessary.
(Refer to "Important information on Programming")
Was the action complete? 
Go to Step 19

19 Operate the DTCs by "Clear the Information" with
scan tool.
Was the action complete? 
Go to Step 20 
20 Attempt to start the engine.
Did the engine start? 
System OK
Refer to
Diagnostic Aids

11A-36 IMMOBILIZER SYSTEM

NO IMMOBILIZER WARNING LAMP
Step Action Value(s) Yes No
1 Check the meter fuse for the instrument cluster
ignition feed circuit.
Is the fuse normal? 
Go to Step 3
Go to Step 2
2 Replace the fuse.
Is the action complete? 
Verify repair
Go to Step 3 

3 1. Key position is "OFF".
2. Disconnect the meter.
3. Disconnect the engine control module (ECM).
4. Check the circuit between meter and ECM for an
open, short to round, or short to voltage.
Also, check the meter circuit for an open or short to
ground and the DLC ground circuit for an open.
Was a problem found? 
Go to Step 4
Go to Step 5
4 Repair or replace the meter circuit.
Was the action complete? 
Go to Step 5

5 1. Key position is "ON," engine "OFF."
2. Observe the check engine lamp.
Is the check engine lamp "ON"? 
Go to Step 6
Go to Step 7
6 Repair or replace the meter.
Was the action complete? 
Go to Step 7 
7 1. Key position is "OFF".
2. Check the check engine lamp bulb.
Is the check engine lamp bulb normal? 
Go to Step 9
Go to Step 8
8 Replace the check engine lamp bulb.
Is the action complete? 
Verify repair
Go to Step 9 

9 1. Key position is "OFF".
2. Connect the meter.
3. Connect the engine control module (ECM).
4. Key position is "ON".
5. Observe the check engine lamp.
Note: If a key switch is turned ON, check engine lamp
will turn on and a check engine lamp will be turned off
after a few seconds.
Is the check engine lamp "ON"? 
Verify repair
Go to Step 10
10 Replace the engine control module (ECM).
IMPORTANT: The replacement ICU must be
programmed the immobilizer data by scan tool.
Was the action complete? 
Verify repair 

IMMOBILIZER SYSTEM 11A-37

CHECK IMMOBILIZER WARNING LAMP ON STEADY
Step Action Value(s) Yes No
1 1. Key position is "OFF".
2. Disconnect the immobilizer control unit (ICU).
3. Disconnect the engine control module (ECM).
4. Key position is "ON," engine "OFF."
5. Observe the check engine lamp.
Is the check engine lamp "ON"? 
Go to Step 2
Go to Step 5
2 1. Key position is "OFF".
2. Disconnect the meter.
3. Key position is "ON," engine "OFF."
4. Observe the check engine lamp.
Is the check engine lamp "ON"? 
Go to Step 3
Go to Step 4
3 Repair or replace the meter.
Was the action complete? 
Verify repair
Go to Step 5 

4 Repair or replace the meter circuit.
(Between meter and ICU/ECM)
Was the action complete? 
Verify repair
Go to Step 5 
5 Check the immobilizer control unit (ICU) circuit.
1. Ignition "OFF," disconnect the ICU.
2. Check the ICU circuit for an open, short to ground,
or short to voltage.
Also, check the ICU ignition feed circuit for an open or
short to ground and the ICU ground circuit for an
open.
Was a problem found? 
Go to Step 6
Go to Step 7
6 Repair or replace the immobilizer unit (ICU) circuit.
Was the action complete? 
Verify repair
Go to Step 7 
7 1. Key position is "OFF".
2. Connect the meter.
3. Connect the immobilizer control unit (ICU).
4. Connect the engine control module (ECM).
5. Key position is "ON".
6. Observe the check engine lamp.
Is the check engine lamp "ON"? 
Verify repair
Refer to
Diagnostic Aids

IMMOBILIZER SYSTEM 11A-39

B0002 IMMOBILIZER NOT PROGRAMMED
Step Action Value(s) Yes No
1 Was the "Immobilizer System Check" performed?

Go to Step 2
Go to Immobilizer
System Check
2 Check the immobilizer programming functions.

Immobilizer control unit (ICU).
If a problem is found, repair as necessary.
(Refer to "Important information on Programming")
Was the action complete? 
Go to Step 3
Go to Step 5
3 Recheck the DTC.
1. Key position is “OFF” and keep the position for
more than 30 seconds.
2. Key position is “ON”.
3. Check the DTC on scan tool.
Is DTC B0002 stored? 
Go to Step 4
Verify repair
4 Replace the immobilizer control unit (ICU).
IMPORTANT:
The replacement ICU must be
programmed the security data by scan tool.
Was the action complete? 
Verify repair 
5 Check the immobilizer programming functions.


Engine control module (ECM).


Immobilizer control unit (ICU).
If a problem is found, repair as necessary.
(Refer to "Important information on Programming")
Was the action complete? 
Verify repair
Go to Step 6
6 Replace the key and lock cylinder assembly and
immobilizer system (ICU and ECM).
IMPORTANT:


ICU and ECM are not replacing simultaneously.


After replace lock cylinders, perform the following
below the items.


Program the immobilizer system.
(Refer to "Important information on Programming")
Was the action complete? 
Verify repair