2003 LEXUS LS430 ignition

a. Register the ECU Communication ID
1. Using SST, connect terminals TC and CG of the DLC3. SST 09843-18040
Fig. 9: Connecting Terminals TC And CG Of DLC3 Using SST

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2. Turn the ignition switch ON (do not start the engine) and leave it as is for 30 minutes.
3. Turn the ignition switch OFF and disconnect terminals TC and CG.
4. Check that the engine starts.
PROBLEM SYMPTOMS TABLE
1.CHECK TRANSPONDER KEY AMPLIFIER
Problem SymptomSuspected AreaProceed To
Engine does not startECU power source circuit
Transponder key ECU assyECU POWER SOURCE CIRCUIT

d. Measure the voltage and resistance of the connector.
Standard:
TRANSPONDER KEY AMPLIFIER - VOLTAGE TABLE
If the result is not as specified, the amplifier may have a malfunction.
e. Inspect using an oscilloscope.
Symbols
(Terminal No.)Wiring
ColorTerminal
DescriptionConditionSpecified
Condition
+B (T8-1) - GND
(T8-7)O-VPower sourceNo key in ignition key
cylinder --> Key inserted0 V --> 4.6 to 5.4V
CODE (T8-4) -
GND (T8-7)R-W - VDemodulated signal
of key code dataNo key in ignition key
cylinder --> Key insertedPulse generation
(see waveform 1)
TXCT (T8-5) -
GND (T8-7)L-B - VKey code output
signalNo key in ignition key
cylinder --> Key insertedPulse generation
(see waveform 2)
GND (T8-7) -
Body groundV - Body
groundGroundAlwaysBelow 1 ohms

Fig. 11: Identifying Waveform 1 Graph
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Waveform 1 (Reference):
WAVEFORM 1 REFERENCE TABLE
Waveform 2 (Reference):
Fig. 12: Identifying Waveform 2 Graph

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WAVEFORM 2 REFERENCE TABLE
TerminalCODE - GND
Tool Setting10 V/DIV., 20 ms/DIV.
ConditionNo key in ignition key cylinder --> Key inserted
TerminalTXCT - GND
Tool Setting5 V/DIV., 20 ms/DIV.
ConditionNo key in ignition key cylinder --> Key inserted

If the result is not as specified, there may be a malfunction on the wire harness side.
c. Reconnect the T9 ECU connector.
d. Measure the voltage of the connector.
Standard:
TRANSPONDER KEY ECU - VOLTAGE TABLE
If the result is not as specified, the ECU may have a malfunction.
e. Inspect using an oscilloscope.
Waveform 1 (Reference):
Body groundground
CPUB (T9-1) -
GND (T9-14)V-Y - W-BBatteryAlways10 to 14V
IG2 (T9-2) -
AGND (T9-13)B-VIgnition switchIgnition switch OFF -->
ON0V --> 10 to 14V
KSW (T9-3) -
AGND (T9-13)LG-B - VUnlock warning
switchNo key in ignition key
cylinder --> Key inserted10 kohms or higher --
> Below 1 ohms
Symbols
(Terminal No.)Wiring
ColorTerminal DescriptionConditionSpecified
Condition
KSW (T9-3) -
AGND (T9-13)LG-B - VUnlock warning switch
No key in ignition key
cylinder --> Key
inserted
10 to 14V 0V
VC5 (T9-9) -
AGND (T9-13)O - VPower sourceIgnition switch OFF --
> ON0 V --> 4.6 to
5.4V
TXCT (T9-12) -
AGND (T9-13)L-B - VTransponder key amplifier
communication signalIgnition switch OFF --
> ONPulse generation
(see waveform 1)
CODE (T9-10) -
AGND (T9-13)R-W - VTransponder key amplifier
communication signalIgnition switch OFF --
> ONPulse generation
(see waveform 2)
EFIO (T9-6) -
AGND (T9-13)B-Y - VECM output signalIgnition switch OFF --
> ONPulse generation
(see waveform 3)
EFII (T9-7) -
AGND (T9-13)GR-R - VECM input signalIgnition switch OFF --
> ONPulse generation
(see waveform 4)

Fig. 14: Identifying Waveform 1 Graph
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WAVEFORM 1 REFERENCE TABLE
Waveform 2 (Reference):
TerminalTXCT - GND
Tool Setting5 V/DIV., 20 ms/DIV.
ConditionIgnition switch OFF --> ON

Fig. 15: Identifying Waveform 2 Graph
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WAVEFORM 2 REFERENCE TABLE
Waveform 3 (Reference):
TerminalCODE - GND
Tool Setting10 V/DIV., 20 ms/DIV.
ConditionIgnition switch OFF --> ON

Fig. 16: Identifying Waveform 3 Graph
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WAVEFORM 3 REFERENCE TABLE
Waveform 4 (Reference):
TerminalEFIO - GND
Tool Setting10 V/DIV., 500 ms/DIV.
ConditionIgnition switch OFF --> ON

Fig. 17: Identifying Waveform 4 Graph
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WAVEFORM 4 REFERENCE TABLE
3.CHECK ECM
TerminalEFII - GND
Tool Setting10 V/DIV., 500 ms/DIV.
ConditionIgnition switch OFF --> ON