keys LEXUS LS430 2003 Factory Repair Manual

Fig. 2: Identifying Engine Immobilizer System Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
1.ENGINE IMMOBILIZER SYSTEM DESCRIPTION
The engine immobilizer system is designed to prevent the vehicle from being stolen. This system uses a
steering lock ECU that stores the key codes of authorized smart keys. If an attempt is made to start the
engine using an unauthorized key, the ECU sends a signal to the ECM to prohibit fuel delivery and
ignition, effectively disabling the engine.
2.FUNCTION OF MAIN COMPONENT
MAIN COMPONENT FUNCTION TABLE
ComponentOutline
Transponder key coil/amplifierWhen key is inserted in ignition key cylinder, key
coil receives key's ID code. Then amplifier
amplifies ID code and outputs it to steering lock
ECU.
Unlock warning switchDetects if key is in ignition key cylinder and outputs
results to steering lock ECU
ECMThrough SFI communication, ECM receives ID
verification results from steering lock ECU. ECM
also verifies ECUs. Then judgement of whether or
not to immobilize engine is made.
Security indicatorDepending on operation of theft warning ECU (theft
deterrent ECU), interior security indicator lamp

a. When adding master keys and sub-keys (additional registration).
1. Register the key code (immobilizer code) in the steering lock ECU.
IMMOBILIZER CODE REGISTRATION TABLE
2. Register the key code (smart code) in the steering lock ECU.
SMART CODE REGISTRATION TABLE
b. When replacing the steering lock ECU (new registration).
1. Register the key code (immobilizer code) in the steering lock ECU.
IMMOBILIZER CODE REGISTRATION TABLE
2. Register the ECU COMMUNICATION ID between the ECM and the steering lock ECU.
ECU COMMUNICATION ID CODE REGISTRATION TABLE
c. When replacing the theft warning ECU.
1. Register the ECU COMMUNICATION ID between the ECM and the steering lock ECU.
THEFT WARNING ECU CODE REGISTRATION TABLE
d. When replacing the ECM.
1. Register the ECU COMMUNICATION ID between the ECM and the steering lock ECU.
REPLACING ECM CODE REGISTRATION TABLE
e. When replacing the steering lock ECU and theft warning ECU at the same time.
1. Register the key code (immobilizer code) in the steering lock ECU.
Target ECUSee
Steering lock ECUStep 3
Target ECUSee
Theft warning ECUSee REGISTRATION
Target ECUSee
Steering lock ECUStep 2
Target ECUSee
Steering lock ECUStep 5
ECMStep 6
Target ECUSee
Steering lock ECUStep 5
Target ECUSee
ECMStep 6

IMMOBILIZER CODE REGISTRATION TABLE
2. Register the key code (smart code) in the steering lock ECU.
SMART CODE REGISTRATION TABLE
3. Register the ECU COMMUNICATION ID between the ECM and the steering lock ECU.
ECU COMMUNICATION CODE REGISTRATION TABLE
f. Erasure of key code.
1. Erase the key codes.
ERASING KEY CODES REGISTRATION DESCRIPTION
2.KEY REGISTRATION IN AUTOMATIC REGISTRATION (NEW REGISTRATION)
a. When an ignition key is inserted into the ignition key cylinder, the key code (immobilizer code)
registration is automatic. In this mode, a maximum of 4 key codes for 3 master keys and 1 sub-key
can be registered. Any order of registration for the master keys and sub-key is fine because the
steering lock ECU can distinguish between different types of keys.
HINT:
When a new steering lock ECU is installed, key codes (immobilizer codes) must be
registered in the steering lock ECU.
New steering lock ECUs are automatically set to automatic key code registration mode.
Automatic Key Code Registration
(New Registration)
Target ECUSee
Steering lock ECUStep 3
Target ECUSee
Theft warning ECUSee REGISTRATION
Target ECUSee
Steering lock ECUStep 5
ECMStep 6
Target ECUSee
Steering lock ECUStep 4

HINT:
The automatic key code registration mode can be forced to end when at least 1 key code (immobilizer
code) for the master key has been registered.
3.REGISTRATION OF ADDITIONAL KEY (ADDITIONAL REGISTRATION)
a. Register an additional key using the hand-held tester.
HINT:
A maximum of 5 master key codes and 3 sub-key codes can be registered.
Registration mode will end if each step is not completed within the specified time.
When the ignition cylinder or the key cylinder set is replaced, remove the transmitter module
from the original master key. Then install this transmitter module to a new key and use the
new key as the master key. If necessary, use this master key to register other keys.
Additional Registration

1.DATA LIST
HINT:
Using the hand-held tester's DATA LIST allows switch, sensor, actuator and other item values to be read
without removing any parts. Reading the DATA LIST early in troubleshooting is one way to save time.
a. Connect the hand-held tester to the Controller Area Network Vehicle Interface Module (CAN
VIM). Then connect the CAN VIM to the DLC3.
b. Turn the ignition switch ON.
c. Read the DATA LIST.
Steering lock ECU:
DATA LIST - STEERING LOCK ECU
Item
Measurement Item/
Display (Range)
Normal ConditionDiagnostic Note
KEY SWUnlock warning switch
signal/ON or OFFON: Key is in ignition
key cylinder OFF: No
key is in ignition key
cylinder-
IMMOBILIZERImmobilizer system
status/ SET or UNSETUNSET: Ignition switch
ON SET: Without key-
RESPONSETransponder chip data/
NG or OKNG: Data error OK: Data
OK-
FRAMETransponder chip data/
NG or OKNG: Data error OK: Data
OK-
SERIAL NUMBERTransponder chip data/
NG or OKNG: Data error OK: Data
OK-
ENCRYPT CODETransponder chip data/
NG or OKNG: Data error OK: Data
OK-
STATUSTransponder chip data/
NG or OKNG: Data error OK: Data
OK-
BCCTransponder chip signal/
NG or OKNG: Incorrect data
sending OK: Correct data
sending-
SUB KEYSub-key code signal/
NOMATCH or MATCHNOMATCH: Unmatched
sub-key code is sent
MATCH: Sub-key code
is sent-
MASTER KEYMaster key code signal/
NOMATCH or MATCHNOMATCH: Unmatched
Master key code is sent
MATCH: Master key
code is sent-
REGIST SUB CODENumber of registered Number of registered -

CIRCUIT DESCRIPTION
This DTC is output when a key with a key code that has not been registered in the ECU is inserted into the
ignition key cylinder.
UNMATCHED KEY CODE DTC REFERENCE TABLE
INSPECTION PROCEDURE
1.DELETE DTC AND INSERT ALL PRESENTLY AVAILABLE KEYS TO CHECK WHETHER
ENGINE STARTS OR NOT
OK: Engine starts.
NG: REPLACE KEY THAT CANNOT START ENGINE
OK: NO PROBLEM (BECAUSE OF KEY RE-REGISTRATION)
CIRCUIT DESCRIPTION
This DTC is output when a key that does not have a transponder chip is inserted into the ignition key cylinder or
if communication between the key and steering lock ECU is not possible.
Fig. 34: Communication Malfunction Circuit Description

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
WIRING DIAGRAM
DTC No.DTC Detection ConditionTrouble Area
B2795Key with unregistered key code is
insertedSmart key

Fig. 35: No Communication In Immobilizer System, DTC B2798: Communication Malfunction No. 2
DTC - Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.READ DATA LIST USING HAND-HELD TESTER
a. Connect the hand-held tester to the CAN VIM. Then connect the CAN VIM to the DLC3.
b. Turn the ignition switch ON with the key that cannot start the engine.
c. Read the DATA LIST.
Steering lock ECU:
DATA LIST - STEERING LOCK ECU
OK: "UNSET" (Ignition switch ON) appears on the screen.
NG: Go to step 2
OK: REPLACE STEERING LOCK ECU
2.CHECK WHETHER ENGINE STARTS WITH OTHER KEYS
a. Check if the en
gine starts with the vehicle's other keys.
Item
Measurement Item/
Display (Range)
Normal ConditionDiagnostic Note
IMMOBILIZERImmobilizer system
status/ SET or UNSETUNSET: Ignition switch
ON SET: Without key-

Fig. 36: Checking Wire Harness (Steering Lock ECU -Transponder Key Amplifier)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR
OK: Go to next step
4.REPLACE TRANSPONDER KEY AMPLIFIER
a. After replacing the transponder key amplifier with a normally functioning amplifier, check that the
engine starts.
OK: Engine starts.
NG: REPLACE STEERING LOCK ECU
OK: END
CIRCUIT DESCRIPTION
This DTC is output when a communication error occurs between the transponder key amplifier and steering
lock ECU. Some possible reasons for the communication error are: 1) 2 or more smart keys are positioned too
close together, or 2) noise is occurring in the communication line. Follow the inspection procedure below.
Fig. 37: Communication Malfunction No. 1 Circuit Description

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
WIRING DIAGRAM

Fig. 38: Communication Malfunction No. 1 - Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.CHECK KEYS
a. Check if the smart key being used is near other smart keys as shown in the illustration. Also, check
if the key ring is in contact with the key grip.
Result:
KEY CHECK RESULT TABLE
ResultProceed to
Key is near other keys and/or key rings is in contact
with key grip.A
Key is not near other keys and/or key ring is not in
contact with the key grip.B

Fig. 39: Checking Keys
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
B: Go to step 3
A: Go to next step
2.CHECK FOR DTCS
a. Separate the keys from each other. Or, remove the key ring.
b. Delete the DTC (See DTC CHECK/CLEAR
).
c. Insert a key into the ignition key cylinder. Remove it. Repeat for all the other keys.
d. Check that no code is output.
NG: Go to step 3
OK: END
3.CHECK STEERING LOCK ECU