2003 LEXUS LS430 Identifying ac

If a malfunction occurs in the vehicle speed sensors, the stop lamp switch, or other related parts during
cruise control driving, the ECU actuates AUTO CANCEL of the cruise control and blinks the CRUISE
main indicator light. This indicator light informs the driver of the malfunction. At the same time, the
malfunction is stored as a diagnostic trouble code.
Fig. 32: Identifying Blinking Pattern Of CRUISE Main Indicator Light

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1.DTC CHECK
a. Connect the hand-held tester to the DLC3.
b. Turn the ignition switch to the ON position.
c. Read the DTCs by following the prompts on the tester screen.
2.DTC CLEAR
a. Connect the hand-held tester to the DLC3.
b. Turn the ignition switch to the ON position.
c. Clear the DTCs following the prompts on the tester screen.
HINT:
Refer to the han
d-held tester operators manual for further details.

Fig. 33: Connecting Hand-Held Tester To DLC3
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1.Constant speed control mode and vehicle-to-vehicle distance control mode:
If the following conditions are detected while the dynamic radar cruise control is in operation, the system
clears the stored vehicle speed in the ECM and cancels the dynamic radar cruise control operation.
Fig. 34: Identifying CRUISE Main Indicator Light And Master Warning Light

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Fig. 35: Fail
-Safe Chart
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2.Only in the vehicle-to-vehicle distance control mode:
If the following conditions are detected while the dynamic radar cruise control is in operation, the system
clears the stored vehicle speed in the ECM and cancels the dynamic radar cruise control operation.
Fig. 36: Identifying CRUISE Main Indicator Light And Master Warning Light

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Fig. 37: Fail
-Safe Chart
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3.Only in the vehicle-to-vehicle distance control mode:
If the following conditions are detected while the dynamic radar cruise control is in operation, the system
maintains the stored vehicle speed in the ECM and cancels the d
ynamic radar cruise control operation.

Fig. 38: Identifying CRUISE Main Indicator Light And Master Warning Light
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Fig. 39: Fail
-Safe Chart (1 Of 2)
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4.Constant speed control mode and vehicle-to-vehicle distance control mode:
If the following conditions are detected while the dynamic radar cruise control is in operation, the system
clears the stored vehicle speed and cancels the dynamic radar cruise control operation.
HINT:
In the vehicle-to-vehicle distance control mode, the stored vehicle speed in the ECM is maintained.
Fig. 40: Fail
-Safe Chart (2 Of 2)
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Fig. 47: Identifying Stop Lamp Switch Assy Connector
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OK: Go To Next Step.
3.CHECK HARNESS AND CONNECTOR (STOP LAMP SWITCH - BATTERY)
a. Measure the voltage according to the value(s) in the table below.
Standard:
STOP LAMP SWITCH TERMINALS VOLTAGE SPECIFICATION
Tester connectionConditionSpecified condition
S19-2 - Body groundAlways10 to 14V
S19-3 - Body groundIgnition SW ON10 to 14V

Fig. 48: Identifying Stop Lamp Switch Assy Connector
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NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: Go To Next Step.
4.INSPECT ECM
a. Reconnect the stop lamp switch connector.
b. Disconnect the E2 and E3 connectors from the ECM.
c. Turn the ignition switch to the ON position.
d. Measure the voltage according to the value(s) in the table below.
Standard:
ECM CONNECTOR TERMINALS VOLTAGE SPECIFICATION
Pedal conditionTester connectionSpecification
DepressedE2-4 (STP) - Body ground10 to 14V
ReleasedE2-4 (STP) - Body groundBelow 1 V

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A: REPLACE ECM (SEE REPLACEMENT
)
5.INSPECT DRIVER SIDE J/B
a. Measure the voltage according to the value(s) in the table below.
Fig. 50: Identifying Driver Side Junction Block ECU Connector Terminals

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Standard:
TESTER CONNECTION SPECIFICATION
NG: Go to step 6
Pedal conditionTester connectionSpecification
DepressedD3-12 (STPO) - Body ground10 to 14V
ReleasedD3-12 (STPO) - Body groundBelow 1 V

OK: REPAIR OR REPLACE HARNESS OR CONNECTOR (DRIVER SIDE J/B ECU - ECM)
6.INSPECT DRIVER SIDE J/B
a. Measure the voltage according to the value(s) in the table below.
Fig. 51: Identifying Driver Side Junction Block ECU Connector Terminals

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Standard:
ECU CONNECTOR TERMINALS VOLTAGE SPECIFICATION
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LAMP SWITCH - DRIVER
SIDE J/B ECU)
OK: REPLACE DRIVER SIDE J/B
Pedal conditionTester connectionSpecification
DepressedD3-13 (STPI) - Body ground10 to 14V
ReleasedD3-13 (STPI) - Body groundBelow 1 V