Lexus RX300 (MCU15). Manual — part 248

R14205

1

2

DI–224

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DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

LEXUS RX300 (RM785E)

INSPECTION PROCEDURE

HINT:
Start the inspection from step 1 in case of using the hand–held tester and start from step 2 in case of not
using the hand–held tester.

1

Check output value of speed sensor.

PREPARATION:
(a)

Connect the hand–held tester to the DLC3.

(b)

Turn the ignition switch ON and push the hand–held tester main switch ON.

(c)

Select the DATALIST mode on the hand–held tester.

CHECK:
Check that there is no difference between the speed value output from the speed sensor displayed by the
hand–held tester and the speed value displayed by the speedometer when driving the vehicle.
OK:

There is almost no difference from the displayed speed value.

HINT:
There is tolerance of ± 10 % in the speedometer indication.

OK

Go to step 4.

NG

2

Check speed sensor.

Front:
PREPARATION:
(a)

Remove the front fender liner.

(b)

Make sure that there is no looseness at the connector
lock part and connecting part of the connector.

(c)

Disconnect the speed sensor connector.

CHECK:
Measure resistance between terminals 1 and 2 of speed sensor
connector.
OK:

Resistance: 1.4 – 1.8 kΩ

CHECK:
Measure resistance between terminals 1 and 2 of speed sensor
connector and body ground.
OK:

Resistance: 1 MΩ or higher

R14213

1

2

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DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

DI–225

LEXUS RX300 (RM785E)

Rear:
PREPARATION:
(a)

Remove the seat cushion and seatback.

(b)

Make sure that there is no looseness at the connector
lock part and connecting part of the connector.

(c)

Disconnect the speed sensor connector.

CHECK:
Measure resistance between terminals 1 and 2 of speed sensor
connector.
OK:

Resistance: 0.6 – 1.8 kΩ

CHECK:
Measure resistance between terminals 1 and 2 of speed sensor
connector and body ground.
OK:

Resistance: 1 MΩ or higher

NG

Replace speed sensor.

NOTICE:
Check the speed sensor signal last (See page DI–205).

OK

3

Check for open and short circuit in harness and connector between each speed
sensor and skid control ECU (See page IN–32).

NG

Repair or replace harness or connector.

OK

BR3795

W04200

Normal Signal Waveform

1 V / Division

2 m/s / Division

GND

DI–226

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DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

LEXUS RX300 (RM785E)

4

Check sensor installation.

CHECK:
Check the speed sensor installation.
OK:

The installation bolt is tightened properly and there is
no clearance between the sensor and front steering
knuckle or rear axle carrier.
Torque: 8.0 N·m (82 kgf·cm, 71 in.·lbf)

NG

Replace speed sensor.

NOTICE:
Check the speed sensor signal last (See page DI–205).

OK

5

Check speed sensor and sensor rotor serrations.

(REFERENCE) INSPECTION USING OSCILLOSCOPE

PREPARATION:
(a)

Remove the skid control ECU with connectors still con-
nected.

(b)

Connect the oscilloscope to the terminals FR+ – FR–, FL+
– FL–, RR+ – RR– or RL+ – RL– of the skid control ECU.

CHECK:
Drive the vehicle with about 20 km/h (12 mph), and check the
signal waveform.
HINT:

S

As the vehicle speed (rpm of the wheels) increases, a
cycle of the waveform becomes shorter and the fluctura-
tion in the output voltage becomes greater.

S

When noise is identified in the waveform on the oscillo-
scope, error signals are generated due to the speed sen-
sor rotor’s scratches, looseness or foreign matter depos-
ited on it.

R00948

BR3720

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DIAGNOSTICS

ABS & BA & TRC & VSC SYSTEM

DI–227

LEXUS RX300 (RM785E)

OK

Check and replace skid control ECU.

NG

6

Check sensor rotor and sensor tip.

Front:
PREPARATION:
Remove the front drive shaft (See page SA–12).
CHECK:
Check the sensor rotor serrations.
OK:

No scratches, missing teeth or foreign objects.

PREPARATION:
Remove the front speed sensor (See page BR–59).
CHECK:
Check the sensor tip.
OK:

No scratches or foreign objects on the sensor tip.

HINT:
If foreign matter (including that on the sensor rotor side) is iden-
tified, remove it and after reassembling, check the output wave-
form.
Rear:
PREPARATION:
Remove the rear drive shaft (See page SA–52).
CHECK:
Check the sensor rotor serrations.
OK:

No scratches, missing teeth or foreign objects.

PREPARATION:
Remove rear speed sensor (See page BR–62).
CHECK:
Check the sensor tip.
OK:

No scratches or foreign objects on the sensor tip.

HINT:
If foreign matter (including that on the sensor rotor side) is iden-
tified, remove it and after reassembling, check the output wave-
form.