2003 LEXUS LS430 actuator

OK: Go to next step
2.INSPECT BATTERY
a. Check the battery voltage.
Standard:
Voltage: 10 to 14 V
NG: INSPECT CHARGING SYSTEM (SEE ON
-VEHICLE INSPECTION )
OK: Go to next step
3.INSPECT SKID CONTROL ECU TERMINAL VOLTAGE (IG1 TERMINAL)
a. Connect the hand-held tester to the DLC3.
b. Start the engine.
c. Select the DATA LIST mode on the hand-held tester.
Fig. 91: DATA LIST Mode Description

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
d. Read the voltage condition output from the ECU displayed on the hand-held tester.
Standard:
"Normal" is displayed.
NG: Go to step 4
OK: REPLACE ABS & TRACTION ACTUATOR ASSY (SEE REPLACEMENT
)
4.INSPECT SKID CONTROL ECU CONNECTOR (GND TERMINAL CONTINUITY)
a. Disconnect the skid control ECU connector.
b. Measure the resistance according to the value (s) in the table below.
Standard:

TESTER CONNECTION SPECIFIED CONDITION
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (GND TERMINAL - BODY
GROUND)
Fig. 92: Identifying Skid Control ECU Connector Terminals

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: CHECK AND REPAIR HARNESS AND CONNECTOR (IG1 TERMINAL - BATTERY)
CIRCUIT DESCRIPTION
Master c
ylinder pressure sensor is connected to the skid control ECU in the actuator.
Tester ConnectionSpecified Condition
S42-32 (GND) - Body groundBelow 1ohms

c. Select the DATA LIST mode on the hand-held tester.
MEASUREMENT ITEM / RANGE (DISPLAY) DESCRIPTION
d. Check that the brake fluid pressure value of the master cylinder pressure sensor observed in the
hand held tester changes when the brake pedal is depressed.
OK: Go to next step
When the pedal is depressed, displayed voltage on the hand-held tester increases.
NG: Go to step 2
OK: REPLACE ABS & TRACTION ACTUATOR ASSY (SEE REPLACEMENT
)
2.INSPECT SKID CONTROL ECU TERMINAL VOLTAGE (STP TERMINAL)
a. Disconnect the skid control ECU connector.
b. Measure the voltage according to the value (s) in the table below.
Standard:
TESTER CONNECTION SPECIFIED CONDITION
NG: CHECK AND REPLACE STOP LIGHT SWITCH CIRCUIT
OK: REPLACE ABS & TRACTION ACTUATOR ASSY (SEE REPLACEMENT
)
ItemMeasurement Item / Range (Display)Normal Condition
MAS CYL PRS
1Master cylinder pressure sensor 1 reading /
min.: 0 V, max.: 5 VWhen brake pedal is released:
0.3 to 0.9V
Tester ConnectionSwitch ConditionSpecified Condition
S42-27 (STP) - Body groundBrake pedal depressed8 to 14V
S42-27 (STP) - Body groundBrake pedal releasedBelow 1 V

OK: Go to next step
5.RECONFIRM DTC
a. Clear the DTC (see DTC CHECK/CLEAR
).
b. Turn the ignition switch to the ON position.
c. Check that the same DTC is recorded (see DTC CHECK/CLEAR
).
OK:
The same DTC is recorded.
NG: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
OK: REPLACE ABS & TRACTION ACTUATOR ASSY (SEE REPLACEMENT
)
6.INSPECT STOP LAMP SWITCH ASSY
a. Disconnect the stop lamp switch assy connector.
b. Measure the resistance according to the value (s) in the table below.
Standard:
TESTER CONNECTION SPECIFIED CONDITION
Switch ConditionTester ConnectionSpecified Condition
Switch pin free1 - 2Below 1 ohms
Switch pin pushed in1 - 21 Mohms or higher

OK: Go to next step
9.RECONFIRM DTC
a. Clear the DTC (see DTC CHECK/CLEAR
).
b. Turn the ignition switch to the ON position.
c. Check that the same DTC is recorded (see DTC CHECK/CLEAR
).
OK:
The same DTC is recorded.
NG: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE
OK: REPLACE ABS & TRACTION ACTUATOR ASSY (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
ABS pump motor is located inside the brake actuator. The motor is used for BA, TRAC and VSC operation.
Fig. 104: DTC C1251/51 Detection Condition And Trouble Area Description Chart

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WIRING DIAGRAM

VEHICLE CONDITION / TEST DETAILS
OK: Go to next step
The operation sound of the ABS motor is heard.
OK: Go to step 2
NG: REPLACE ABS & TRACTION ACTUATOR ASSY (SEE REPLACEMENT
)
2.INSPECT HARNESS AND CONNECTOR (GND2 OF SKID CONTROL ECU AND BODY
GROUND)
a. Disconnect the skid control ECU connector.
b. Measure the resistance according to the value (s) in the table below.
Standard:
TESTER CONNECTION SPECIFIED CONDITION
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
ItemVehicle Condition / Test DetailsVehicle Condition / Test Details
Turns ABS MOT RELAYABS motor relay / ON or OFFON: Motor relay ON
Tester ConnectionSpecified Condition
S42-1 (GND2) - Body groundBelow 1 ohms

Fig. 106: Identifying Skid Control ECU Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: REPLACE ABS & TRACTION ACTUATOR ASSY (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
The brake pedal load sensing switch is turned on when the brake pedal is depressed with force exceeding a
predetermined level.
The skid control ECU detects if the brake pedal is depressed or not via this circuit.

Fig. 111: Identifying Skid Control ECU Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: REPLACE ABS & TRACTION ACTUATOR ASSY (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION