2003 LEXUS LS430 key

Fig. 1: Identifying Components & Replacements Location of Engine Immobilizer System (W/Smart Key
System)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

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

3.SYSTEM FUNCTION
When the steering lock ECU detects that the unlock warning switch is ON, the ECU provides current to
the transponder key coil and produces a faint electric wave. A transponder chip in the key and receives
the faint electric wave. Upon receiving the faint electric wave, the transponder chip outputs a key ID code
signal. The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then
the signal is transmitted to the ECU.
The ECU matches the key's ID code with the vehicle's ID code, which was previously registered in the
ECU and then communicates the results to the ECM using SFI communication.
After the identification results show that the key's ID code matches the vehicle's ID code and the ECU has
confirmed their match: 1) the immobilizer system does not immobilize the engine and the engine starting
controls (fuel injection control and ignition control) enter standby mode; and 2) the ECU transmits a
security indicator signal that communicates "indicator off" to the theft warning ECU (theft deterrent
ECU). Then, the theft warning ECU turns off the security indicator lamp.
HINT:
Use this procedure to troubleshoot the engine immobilizer system.
The hand-held tester should be used in steps 4, 5 and 7.
1.VEHICLE BROUGHT TO WORKSHOP
2.CUSTOMER PROBLEM ANALYSIS CHECK AND SYMPTOM CHECK (See CUSTOMER
PROBLEM ANALYSIS CHECK )
3.CRANK ENGINE FOR MORE THAN 10 SECONDS
4.CHECK FOR DTCS
a. Check for DTCs and note any codes that are output.
b. Delete the DTC.
c. Recheck for DTCs. Based on the DTC output in (a), try to force output of the same SFI system
DTC or engine immobilizer system DTC by simulating the operation indicated by the DTC.
1. If the DTC does not reoccur, proceed to A.
2. If the SFI system DTC reoccurs, proceed to B.
3. If the engine immobilizer system DTC reoccurs, proceed to C.
B: Go to SFI SYSTEM (See HOW TO PROCEED WITH TROUBLESHOOTING
)
C: Go to step 8
illuminates or starts blinking.

A: Go to next step
5.READ DATA LIST USING HAND-HELD TESTER
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 and push the hand-held tester main switch ON.
c. Read the DATA LIST.
Steering lock ECU:
DATA LIST - STEERING LOCK ECU
OK: "ON" (Key is in ignition key cylinder) appears on the screen.
NG: Go to DTC B2780 (See DTC B2780 PUSH SWITCH/KEY UNLOCK WARNING SWITCH
MALFUNCTION )
OK: Go to next step
6.See PROBLEM SYMPTOMS TABLE
)
a. If the fault is not listed on the problem symptoms table, proceed to A.
b. If the fault is listed on the problem symptoms table, proceed to B.
B: Go to step 8
A: Go to next step
7.OVERALL ANALYSIS AND TROUBLESHOOTING
a. See DATA LIST/ACTIVE TEST
)
1. Inspection with the hand-held tester (DATA LIST)
2. Inspection with the hand-held tester (ACTIVE TEST)
b. See TERMINALS OF ECU
)
8.ADJUST, REPAIR OR REPLACE
9.CONFIRMATION TEST
END
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-

Fig. 3: Identifying Customer Problem Analysis Check Sheet
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
HINT:
The key has 3 codes: the key code (immobilizer code), the smart code and wireless code. All of these code types
need to be registered. Refer to REGISTRATION
for the smart code (wireless code) registration procedures.
1.DESCRIPTION OF CODE REGISTRATION

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

Fig. 4: Automatic Key Code Registration Flowchart (New Registration)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
HINT:
When no key is inserted into the ignition key cylinder in automatic key code registration
mode, the security indicator remains on.
When the immobilizer system is operating normally and the key is pulled out, the security
indicator blinks continuously.
If the key code registration has failed in automatic key code registration mode, code 2-1 will
be output from the security indicator. Trying to re-register an already registered key will
cause code 2-2 to be output when the key is inserted. If the number of registered key codes