LEXUS LS430 2003 Factory Repair Manual

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. 38: Communication Malfunction No. 1 - Wiring Diagram
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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
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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

a. Using an oscilloscope or the hand-held tester check the waveform between the terminals of the T8
amplifier connector and S46 ECU connector. The waveform should be similar to the illustration on
the left.
OK: No noise is present (see Fig. 40
).
Fig. 40: Checking If Noise Is Present

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STEERING LOCK ECU - WAVEFORM TABLE
TOOL SETTING REFERENCE TABLE
NG: FIND CAUSE OF NOISE AND REMOVE IT
OK: Go to next step
4.CHECK WIRE HARNESS (STEERING LOCK ECU - TRANSPONDER KEY AMPLIFIER)
a. Disconnect the S46 ECU connector.
b. Disconnect the T8 amplifier connector.
c. Measure the resistance of the terminals of the connectors.
Tester connectionSpecified condition
S46-17 (CODE) - T8-4 (CODE)No noise is present
Tool Setting10 V/DIV., 20 ms/DIV.
ConditionIgnition switch OFF -> ON

Standard:
STEERING LOCK ECU - TRANSPONDER KEY AMPLIFIER - RESISTANCE TABLE
Tester connectionSpecified condition
S46-17 (CODE) - T8-4 (CODE)Below 1 ohms

Fig. 41: 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
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