2004 ISUZU TF SERIES immobilizer

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

11A-38 IMMOBILIZER SYSTEM

B0001 REPLACE ELECTRONIC CONTROL UNIT (ECU) (IMMOBILIZER FAULT)
Step Action Value(s) Yes No
1
Was the "Immobilizer System Check" performed? 
Go to Step 2
Go to Immobilizer
System Check
2 Recheck the DTC.
1. Key position is “OFF”.
2. Install the scan tool on vehicle.
3. Key position is “ON”.
4. Check the DTC on scan tool.
Is DTC B0001 stored? 
Go to Step 3
Refer to
Diagnostic Aids
3 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 4
Go to Step 5
4 Repair or replace the immobilizer unit (ICU) circuit.
Was the action complete? 
Verify repair

5 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 

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 

11A-40 IMMOBILIZER SYSTEM

B0003 TRANSPONDER KEY PROBLEM
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 key.
Is a key peculiar to a vehicle? 
Go to Step 3
Refer to
Diagnostic Aids
3 Check the immobilizer programming functions.


All transponder (Key).
If a problem is found, repair as necessary.
(Refer to "Important information on Programming")
Was the action complete? 
Go to Step 4
Go to Step 5
4 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 B0003 stored? 
Go to Step 5
Verify repair
5 Recheck the DTC.
1. Non-OEM parts switch is "OFF" or remove the Non-
OEM parts.
2. Remove the accessory and another key from key.
3. Move the vehicle to a new location.
4. Key position is “OFF” and keep the position for more
than 30 seconds.
5. Key position is “ON”.
6. Check the DTC on scan tool.
Is DTC B0003 stored? 
Go to Step 6
Verify repair
6 Check the immobilizer coil (antenna) circuit.
1. Key position is “OFF”.
2. Disconnect the immobilizer control unit (ICU).
(immobilizer coil circuit : 3 pin connector)
3. Check the immobilizer coil 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 7
Go to Step 8
7 Repair or replace the immobilizer coil (antenna) circuit.
Was the action complete? 
Verify repair 
8 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 B0003 stored? 
Go to Step 9
Verify repair

IMMOBILIZER SYSTEM 11A-41

Step Action Value(s) Yes No
9 Replace the immobilizer control unit (ICU).
IMPORTANT:
The replacement ICU must be
programmed the security data by scan tool.
Was the action complete? 
Go to Step 10 
10 Check the immobilizer programming functions.

Immobilizer control unit (ICU).


All transponder (Key).
If a problem is found, repair as necessary.
(Refer to "Important information on Programming")
Was the action complete? 
Go to Step 11

11 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 B0003 stored? 
Go to Step 12
Verify repair
12 Replace the transponder (Key).
IMPORTANT:
The replacement transponder (key) must
be programmed the security data by scan tool.
Was the action complete? 
Verify repair 

11A-42 IMMOBILIZER SYSTEM

B0004 IMMOBILIZER COIL CIRCUIT (ANTENNA COIL FAULT)
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 coil (antenna) circuit.
1. Key position is “OFF”.
2. Disconnect the immobilizer control unit (ICU).
(immobilizer coil circuit : 3 pin connector)
3. Check the immobilizer coil 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 3
Go to Step 4
3 Repair or replace the immobilizer coil (antenna).
Was the action complete? 
Verify repair 
4 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 B0004 stored? 
Go to Step 5
Verify repair
5 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


IMMOBILIZER SYSTEM 11A-43

B0005 COMMUNICATION LINE W VOLTAGE LOW
Step Action Value(s) Yes No
1
Was the "Immobilizer System Check" performed? 
Go to Step 2
Go to Immobilizer
System Check
2 Recheck the DTC.
1. Key position is “OFF”.
2. Install the scan tool on vehicle.
3. Key position is “ON”.
4. Check the DTC on scan tool.
Is DTC B0005 stored? 
Go to Step 3
Refer to
Diagnostic Aids
3 Check the immobilizer communication W line circuit.
1. Key position is “OFF”.
2. Disconnect the immobilizer control unit (ICU).
3. Disconnect the engine control module (ECM).
4. Check the immobilizer communication W line
circuit for an open, short to ground, or short to
voltage.
Also, check the ICU and ECM ignition feed circuits for
an open or short to ground and the ICU and ECM
ground circuit for an open.
Was a problem found? 
Go to Step 4
Go to Step 5
4 Repair or replace the immobilizer communication W
line circuit.
Was the action complete? 
Verify repair 
5 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 

11A-44 IMMOBILIZER SYSTEM

B0006 COMMUNICATION LINE W VOLTAGE HIGH
Step Action Value(s) Yes No
1
Was the "Immobilizer System Check" performed? 
Go to Step 2
Go to Immobilizer
System Check
2 Recheck the DTC.
1. Key position is “OFF”.
2. Install the scan tool on vehicle.
3. Key position is “ON”.
4. Check the DTC on scan tool.
Is DTC B0006 stored? 
Go to Step 3
Refer to
Diagnostic Aids
3 Check the immobilizer communication W line circuit.
1. Key position is “OFF”.
2. Disconnect the immobilizer control unit (ICU).
3. Disconnect the engine control module (ECM).
4. Check the immobilizer communication W line
circuit for an open, short to ground, or short to
voltage.
Also, check the ICU and ECM ignition feed circuits for
an open or short to ground and the ICU and ECM
ground circuit for an open.
Was a problem found? 
Go to Step 4
Go to Step 5
4 Repair or replace the immobilizer communication W
line circuit.
Was the action complete? 
Verify repair 
5 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