ignition ISUZU TF SERIES 2004 Workshop Manual

11A-56 IMMOBILIZER SYSTEM

B0016 FREQUENCY SIGNAL HIGH (Only 4JA1-L Engine)
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 B0016 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 (Engine
immobilizer unit).
4. Check the immobilizer communication W line
circuit for an open, short to ground, or short to
voltage.
Also, check the ICU and Engine immobilizer unit
ignition feed circuits for an open or short to ground
and the ICU and Engine immobilizer unit 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 

IMMOBILIZER SYSTEM 11A-57

B0023 IMMOBILIZER COIL CIRCUIT (ANTENNA COIL FAULT)
(Only 4JA1-T Engine)
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 B0023 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-59

B0055 EEPROM ERROR
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 B0055 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 

ANTITHEFT SYSTEM 11B – 7
DIAGRAMS AND SCHEMATICS
SYSTEM WIRING DIAGRAMS
M
M
M
M
M
M
M
M
- +
ANTITHEFT CONTROL UNIT BATTERY
(12V)
80A10A
ACC Ignition switch20A
10A
10A
antitheft horn
power supply
power supply
door lock motors
hazard relay(RH)
flashers(RH)
hazard relay(LH)
flashers(LH)
status LED
immobilizer controller
daiagnostc conector
groundlock lock
locklock lock alarm trigger
super lock
unlock unlock
(unlock)
(unlock)
unlock
driver door rear door(LH) rear door(RH)rear door(LH) rear door(RH)
assist door driver door assist doordriver door
assist door
driver door assist door
engine hood contact switch
door contact switch
auto door lock switch auto door lock
door lock cylinder
disarmwith super
lock without
super lock

ANTITHEFT SYSTEM 11B – 25
Tech-2 Features
1. Tech-2 is a 12volt system. Do not apply 24
volts.
2. After connecting and/or installing the vehicle
communication interface (VCI) module, PCMCIA
card and data link connector (DLC) to the Tech-
2, connect the tool to the vehicle DLC.
3. Make sure the tech-2 is OFF when removing or
installing the PCMCIA card.
4. The Tech-2 has the capability of two or three
snapshot.
5. The PCMCIA card is sensitive to magnetism and
static electricity, so care should be taken in the
handling of the card.
6. Always return to the Main Menu by pressing
the EXIT key several times before shutting
down.
7. To clear diagnostic trouble codes (DTCs), open
Application Menu and press “Clear DTC”.
Getting Started
Before operating the Isuzu PCMCIA card with the
Tech-2, the following steps must be performed:
1. The Isuzu System PCMCIA card inserts into the
Tech-2.
2. Connect the SAE 16/19 adapter to the DLC
cable.
3. Connect the DLC cable to the Tech-2.
4. Mark sure the vehicle ignition is off.
5. Connect the Tech-2 SAE 16/19 adapter to the
vehicle DLC.
6. Turn the vehicle ignition (key) switch.
7. Power the Tech-2 ON and verify the Tech-2
power up display.
8 7 6 5 4 3 2 1
16 15 14 13 12 11 10 9
060R300015
Press (ENTER) To Continue
060RW009

ANTITHEFT SYSTEM 11B – 37
Antitheft System Check
Step Action Value (s) Yes No
1
2
3
4
5
6
7
8
91. Key position is “ACC”, shut all doors and
bonnet.
2. Observe the antitheft lamp.
Note: When a key switch is “ACC”, antithft
lamp will turn on and a antitheft lamp (LED)
will be flashing after 10 seconds.
Is the antitheft lamp "ON” or flashing?
1. Key position is “ON”, engine “OFF”.
2. Observe the antitheft lamp.
3. Key position is turned “ACC”.
4. Check the antitheft lamp will be turned
flashing and lamp will be turned ACC after 10
seconds.
Is the antitheft lamp flashing?
1. Key position is “OFF”.
2. Install the Tech-2.
3. Key position is “ON” or “OFF”.
4. Attempt to display antitheft data with the
Tech-2.
Does the Tech-2 display antitheft data?
1. Key position is “OFF”, disconnect the
antitheft control unit (ACU).
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?
Repair or replace the DLC (Data Link Connector)
circuit.
Was the action complete?
1. Check the ACU ground circuit for an open, or
short to voltage. Also, check the ACU ignition
feed circuit for an open or short to ground
and the ACU ground circuit for an open.
2. If a problem is found, repair as necessary.
Was the problem found?
Replace the antitheft control unit (ACU).
IMPORTANT: The replacement ACU must be
programmed the antitheft data by Tech-2.
Was the action complete?
Select “Display DTCs” with the Tech-2.
Are any DTCs stored?
1. Observe the antitheft data list on Tech-2.
2. If a problem is found, repair as necessary.
Was the problem found?—
—
—
—
—
—
—
—
—Go to Step 2
Go to
DTC table
Go to Step 9
Go to Step 5
Go to Step 3
Verfy repair
Go to Step 8
Go to applicable
DTC table
System OKGo to
“No antitheft
lamp”
Go to Step 3
Go to Step 4
Go to Step 6
—
Go to Step 7
—
—
Go to
applicable
section

11B – 38 ANTITHEFT SYSTEM
No Antitheft Lamp
Step Action Value (s) Yes No
1
2
3
4
5
6Check the fuse for the antitheft power feed
circuit. (10A)
If a problem found, repair as necessary.
Was the probem found?
Is the action complete?
1. Check the ACU ground circuit for an open, or
short to voltage. Also, check the ACU ignition
feed circuit for an open or short to ground
and the ACU ground circuit for an open.
2. If a problem is found, repair as necessary.
Was the problem found?
1. Check the antitheft lamp LED circuit for an
open, or short to voltage.
2. If a problem is found, repair as necessary.
Was the problem found?
1. Key position is “OFF”.
2. Install the Tech-2.
3. Key position is “ACC” or “OFF”.
4. Observe to display lamp data with the Tech-2.
Does the Tech-2 display antitheft lamp data ON?
Replace the antitheft lamp.
Replace the antitheft control unit (ACU).
IMPORTANT:The replacement ACU must be
programmed the antitheft data by Tech-2.
Was the action complete?—
—
—
—
—
—Verify repair
Verfy repair
Verify repair
Go to Step 5
Verify repair
Verify repairGo to Step 2
Go to Step 3
Go to Step 4
Go to Step 6
—
—

11B – 42 ANTITHEFT SYSTEM
DTC 20 Broken wire to door lock actuators
Step Action Value (s) Yes No
1
2
3
4
5Was the Antitheft System Check
performed?
Recheck the DTC.
1. Key position is “OFF”.
2. Install the Tech-2 on vehicle.
3. Key position is “ON”.
4. Check the DTC on the Tech-2.
Is DTC 20 stored?
Check the door lock actuator circuit.
1. Key position is “OFF”.
2. Disconnect the antitheft control unit (ACU).
3. Disconnect the door lock motor.
4. Check the antitheft/door lock motor line
circuit for an open, short to ground.
Also, check the ignition feed circuits for an
open or short to ground and the ACU ground
circuit for an open.
Was a problem found?
Repair or replace the antitheft/door lock motor
circuit.
Was the action complete?
Replace the antitheft control unit (ACU).
IMPORTANT: The replacement ACU must be
programmed the security data by the tech2.
Was the action complete?—
—
—
—
—Go to Step 2
Go to Step 3
Go to Step 4
Verify repair
Verify repairGo to antitheft
System Check
Refer to
Diagnostic Aids
Go to Step 5
—
—

11B – 48 ANTITHEFT SYSTEM
DTC 28 Input Immobilizer short circuit to ground
Step Action Value (s) Yes No
1
2
3
4
5Was the Antitheft System Check
performed?
Recheck the DTC.
1. Key position is “OFF”.
2. Install the Tech-2 on vehicle.
3. Key position is “ON”.
4. Check the DTC on the Tech-2.
Is DTC 28 stored?
Check the driver door locking motor function.
line circuit.
1. Key position is “OFF”.
2. Install the Tech-2 on vehicle.
3. Key position is “ON”.
4. Check the antitheft/Immobilizer communi-
cation line circuit for short to voltage, short to
ground.
Also, check the ICU and ACU ignition feed
circuits for an open or short to ground and
the ICU and ACU ground circuit for an open.
Was a problem found?
Repair or replace the antitheft/Immobilizer
communication line circuit.
Was the action complete?
Replace the antitheft control unit (ACU).
IMPORTANT: The replacement ACU must be
programmed the security data by the Tech-2.
Was the action complete?—
—
—
—
—Go to Step 2
Go to Step 3
Go to Step 4
Verify repair
Verify repairGo to antitheft
System Check
Refer to
Diagnostic Aids
Go to Step 5
—
—

ANTITHEFT SYSTEM 11B – 49
DTC 29 Broken Wire To Immobilizer
Step Action Value (s) Yes No
1
2
3
4
5Was the Antitheft System Check
performed?
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 the Tech-2.
Is DTC 29 stored?
Check the antitheft/immobilizer communication
line circuit.
1. Key position is “OFF”.
2. Disconnect the antitheft control unit (ACU).
3. Disconnect the immobilizer control unit (ICU).
4. Check the antitheft/Immobilizer communi-
cation line circuit for an open, short to
ground.
Also, check the ICU and ACU ignition feed
circuits for an open or short to ground and
the ICU and ACU ground circuit for an open.
Was a problem found?
Repair or replace the antitheft/Immobilizer
communication line circuit.
Was the action complete?
Replace the antitheft control unit (ACU).
IMPORTANT: The replacement ACU must be
programmed the security data by the Tech-2.
Was the action complete?—
—
—
—
—Go to Step 2
Go to Step 3
Go to Step 4
Verify repair
Verify repairGo to antitheft
System Check
Refer to
Diagnostic Aids
Go to Step 5
—
—