2003 LEXUS LS430 Wiring engine

Fig. 204: Identifying Passenger Side Junction Block Assy
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NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (See ELECTRONIC CIRCUIT
INSPECTION PROCEDURE )
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
PATTERN SELECT SWITCH CIRCUIT (SNOW)
CIRCUIT DESCRIPTION
Passenger side J/B ECU receives pattern select switch information, and sends it through the multiplex
communication system and CAN system to the ECM.
ECT SNOW is the system that operates the throttle motor to control engine output to reduce skidding of the
driving wheels, guarantee takeoff acceleration, driving straightness and turning stability.
WIRING DIAGRAM

Fig. 205: Pattern Select Switch Circuit (SNOW) - Wiring Diagram
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INSPECTION PROCEDURE
1.DRIVING TEST
a. Start the engine.
b. Turn the ECT SNOW switch "OFF" (Normal drive mode).
c. Confirm vehicle response by driving from a parked position to fully depressing the accelerator
pedal.
d. Turn the ECT SNOW switch "ON" and perform the same check as (c).
Confirm that there is a difference between ECT SNOW switch "ON" and "OFF".
Driving test should be done on a paved road (a nonskid road).
Make sure not to use the TRAC system when testing a vehicle equipped with one.
OK:
There is a difference in acceleration between "ON" and "OFF".
NG: Go to step 2
OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
2.CHECK HARNESS AND CONNECTOR (PATTERN SELECT SWITCH ASSY NO. 1 - BODY
GROUND)

CIRCUIT DESCRIPTION
This DTC will be output if the steering lock ECU does not detect that the unlock warning switch is ON even
when the ignition switch is ON. Under the normal conditions, the unlock warning switch is ON when the
ignition switch is ON.
Fig. 29: Push Switch/Key Unlock Warning Switch Malfunction Circuit Description

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WIRING DIAGRAM
Fig. 30: Push Switch/Key Unlock Warning Switch Malfunction
- Wiring Diagram
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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
Measurement Item/

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

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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
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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)
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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

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WIRING DIAGRAM

Fig. 41: Checking Wire Harness (Steering Lock ECU -Transponder Key Amplifier)
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NG: REPAIR OR REPLACE HARNESS AND CONNECTOR
OK: Go to next step
5.CHECK OPERATION OF 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: 1) the ECM detects errors in its own communications with the steering lock ECU; 2)
the ECM detects errors in the communication lines; and 3) the ECU communication ID between the steering
lock ECU and the ECM are different and an engine start is attempted.
Before troubleshooting for this DTC, make sure no steering lock ECU DTCs are present. If the steering lock
ECU has a key code related DTC, repair it first.
Fig. 42: Engine Immobilizer System Malfunction Circuit Description

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WIRING DIAGRAM

Fig. 43: Engine Immobilizer System Malfunction - Wiring Diagram
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INSPECTION PROCEDURE
1.CHECK WIRE HARNESS (STEERING LOCK ECU - ECM)
a. Disconnect the S46 ECU connector.
b. Disconnect the E2 ECM connector
c. Measure the resistance of the wire harness side connectors.
Standard:
STEERING LOCK ECU - ECM - RESISTANCE TABLE
Tester connectionSpecified condition
S46-13 (EFIO) - E2-6 (IMI)Below 1 ohms
S46-4 (EFII) - E2-7 (IMO)Below 1 ohms
S46-13 (EFIO) or E2-6 (IMI) - Body ground10 kohms or higher
S46-4 (EFII) or E2-7 (IMO) - Body ground10 kohms or higher