ECU LEXUS LS430 2003 Factory Owner's Manual

b. Measure the resistance according to the value (s) in the table below.
Standard:
TESTER CONNECTION SPECIFIED CONDITION LH:
TESTER CONNECTION SPECIFIED CONDITION RH:
c. Measure the resistance according to the value (s) in the table below.
Standard:
TESTER CONNECTION SPECIFIED CONDITION LH:
TESTER CONNECTION SPECIFIED CONDITION RH:
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: Go to next step
6.INSPECT SPEED SENSOR AND SENSOR ROTOR SERRATIONS
INSPECTION USING OSCILLOSCOPE
a. Connect the oscilloscope to terminal FR+ - FR- or FL+ - FL- of the skid control ECU.
b. Drive the vehicle at approximately 19 mph (30 km/h), and check the signal waveform.
OK: Go to next step
A waveform as shown in a figure should be output.
HINT:
Tester ConnectionSpecified Condition
S42-18 (FL+) - A8-2 (FL+)Below 1 ohms
S42-4 (FL-) - A8-1 (FL-)Below 1 ohms
Tester ConnectionSpecified Condition
S42-3 (FR+) - A7-2 (FR+)Below 1 ohms
S42-17 (FR-) - A7-1 (FR-)Below 1 ohms
Tester ConnectionSpecified Condition
S42-18 (FL+) - Body ground1 Mohms or higher
S42-4 (FL-) - Body ground1 Mohms or higher
Tester ConnectionSpecified Condition
S42-3 (FR+) - Body ground1 Mohms or higher
S42-17 (FR-) - Body ground1 Mohms or higher

NG: Go to step 4
OK: Go to next step
3.INSPECT SPEED SENSOR AND SENSOR ROTOR SERRATIONS
Fig. 55: Normal Signal Waveform

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION USING OSCILLOSCOPE
a. Connect the oscilloscope to terminals RR+ - RR- or RL+ - RL- of the skid control ECU.
b. Drive the vehicle at approximately 19 mph (30 km/h), and check the signal waveform.
OK: Go to next step
A waveform as shown in a figure should be output.
HINT:
As the vehicle speed (wheel revolution speed) increases, a cycle of the waveform narrows and the

fluctuation in the output voltage becomes greater.
When noise is identified in the waveform on the oscilloscope, error signals are generated due to the
speed sensor rotor's scratches, looseness or foreign matter attached to it.
NG: Go to step 7
OK: REPLACE ABS & TRACTION ACTUATOR ASSY (SEE REPLACEMENT
)
4.INSPECT REAR SPEED SENSOR
Fig. 56: Inspecting Rear Speed Sensor

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Remove the rear seat cushion and seatback.
b. Make sure that the speed sensor connector and the wire harness side connector are securely
connected.
c. Disconnect the speed sensor connector.
d. Measure the resistance accordin
g to the value (s) in the table below.

Standard:
TESTER CONNECTION SPECIFIED CONDITION LH:
TESTER CONNECTION SPECIFIED CONDITION RH:
e. Measure the resistance according to the value (s) in the table below.
Standard:
TESTER CONNECTION SPECIFIED CONDITION LH:
TESTER CONNECTION SPECIFIED CONDITION RH:
NG: REPLACE REAR SPEED SENSOR (SEE REPLACEMENT
)
OK: Go to next step
5.CHECK HARNESS AND CONNECTOR (REAR SPEED SENSOR - SKID CONTROL ECU)
Tester ConnectionSpecified Condition
(A31-1) - (A31-2)0.6 to 1.8 kohms
Tester ConnectionSpecified Condition
(A30-1) - (A30-2)0.6 to 1.8 kohms
Tester ConnectionSpecified Condition
(A31-1) - Body ground1 Mohms or higher
(A31-2) - Body ground1 Mohms or higher
Tester ConnectionSpecified Condition
(A30-1) - Body ground1 Mohms or higher
(A30-2) - Body ground1 Mohms or higher

Fig. 57: Identifying Skid Control ECU Connector And Rear Speed Sensor Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. Disconnect the skid control ECU connector and the rear speed sensor connector.
b. Measure the resistance according to the value (s) in the table below.
Standard:
TESTER CONNECTION SPECIFIED CONDITION LH:

Fig. 58: Normal Signal Waveform
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION USING OSCILLOSCOPE
a. Connect the oscilloscope to terminals RR+ - RR- or RL+ - RL- of the skid control ECU.
b. Drive the vehicle at approximately 19 mph (30 km/h), and check the signal waveform.
OK: Go to next step
A waveform as shown in a figure should be output.
HINT:
As the vehicle speed (wheel revolution speed) increases, a cycle of the waveform narrows and the
fluctuation in the output voltage becomes greater.
When noise is identified in the waveform on the oscilloscope, error signals are generated due to the
speed sensor rotor's scratches, looseness or foreign matter attached to it.
NG: Go to step 7

OK: Go to next step
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
The ABS motor relays consist of 2 relays are included in the engine room No.3 R/B.
The ABS cut relay is turned on after turning the ignition switch to the ON position. If the DTCs in the
ABS pump motor circuit are memorized, the ABS cut relay cuts off the power supply to the ABS motor
relay and performs the fail safe.
While any of the ABS, BA, TRAC and VSC is operating, the skid control ECU (included in the actuator)
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If the voltage applied to the ABS motor relays (+BM) drops below the condition that detects the DTCs
due to the shorta
ge of the battery or alternator output, the DTCs may be memorized.

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: Go to next step
7.CHECK HARNESS AND CONNECTOR (ABS MOTOR RELAY - SKID CONTROL ECU)
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
c. Measure the resistance accordin
g to the value (s) in the table below.
Tester ConnectionSpecified Condition
5 (ABS MOTOR Relay) - 3 (ABS cut relay)Below 1 ohms
Tester ConnectionSpecified Condition
S42-2 (BM) - 3 (Engine room R/B)Below 1 ohms

Fig. 69: Identifying Skid Control ECU Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: REPLACE ABS & TRACTION ACTUATOR ASSY (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
The ABS solenoid relay is built in the ABS & TRACTION Actuator assy. This relay supplies power to each
ABS solenoid. If the initial check is OK, after the ignition switch is turned to the ON position, the relay stays
on.
Fig. 70: DTC C0278/11 And DTC C0279/12 Detecting Condition And Trouble Area

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
WIRING DIAGRAM

NG: CHECK FOR SHORT IN ALL HARNESS AND CONNECTOR CONNECTED TO FUSE
AND REPLACE FUSE
OK: Go to next step
2.INSPECT SKID CONTROL ECU CONNECTOR (+BS TERMINAL VOLTAGE)
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
c. Measure the resistance according to the value (s) in the table below.
Standard:
TESTER CONNECTION SPECIFIED CONDITION
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: Go to next step
Tester ConnectionSpecified Condition
S42-31 (+BS) - Body ground10 to 14V
Tester ConnectionSpecified Condition
S42-32 (GND) - Body groundBelow 1