Lexus SC300 / Lexus SC400. Manual — part 228

(Speed Sensor)

REMOVAL AND INSTALLATION OF
SPEED SENSOR

1.

REMOVE SPEED SENSOR
(a) Jack up the vehicle.
(b) Disconnect connector and control rod.
(c) Remove a bolt and sensor.

2.

INSTALL SPEED SENSOR
For installation, follow the removal procedure in reverse.

INSPECTION OF SPEED SENSOR

INSPECT SPEED SENSOR

(Operation)
(a) Connect the positive (+) lead from battery to terminal 1

and negative (–) lead to terminal 2.

(b) Connect the positive (+) lead from tester to terminal 3

and negative (–) lead to terminal 2.

(c) Revolve

shaft.

(d) Check that there is voltage change from approx. 0V to

11V or more between terminal 2 and 3.

HINT: The voltage change should be 4 times per each revolu-
tion of the speed sensor shaft.
If operation is not as specified, replace the sensor.
(Sensor circuit)
Disconnect connector from sensor and inspect the connector
on wire harness side as shown.

Check for

Tester connection

Condition

Specified value

Voltage

1 Ground

Ignition switch

ON

Battery positive voltage

g

1–Ground

Ignition switch
position

LOCK or ACC

No voltage

If circuit is not as specified, inspect power source or wire
harness.

–

BODY ELECTRICAL SYSTEM

Combination Meter

BE–110

TRAC PUMP AND ACCUMULATOR
TRAC PUMP AND ACCUMULATOR
REMOVAL AND INSTALLATION

BR0F9–03

Remove and install the part, as shown.

MAIN POINTS OF REMOVAL AND
INSTALLATION

1.

DRAIN OUT HIGH PRESSURE FLUID

(a) Connect a vinyl tube to the TRAC actuator bleeder plug, then

loosen the bleeder plug.

(b) When the fluid has flowed out, tighten the bleeder plug.

CAUTION: Since the fluid is under high pressure, it could
spray out with great force, so be careful.

2.

DISCONNECT AND CONNECT BRAKE LINE
Using SST, disconnect and connect the brake line from/to the
accumulator.
SST 09751–36011

Torque: 15 N

⋅

m (155 kgf

⋅

cm, 11 ft

⋅

lbf)

3.

BLEED BRAKE SYSTEM AND TRAC SYSTEM
(See page

BR–8

)

BR–162

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

TRAC PUMP AND ACCUMULATOR
DISASSEMBLY AND ASSEMBLY

BR0FA–03

Disassemble and assemble the parts, as shown.

MAIN POINT

DISPOSAL METHOD OF TRAC ACCUMULATOR

(a) Loosen

the gas plug about 2 turns to a position where the gas

can leak out.

(b) After

confirming

that all the gas has been drained out remove

the gas plug and dispose of the accumulator.
HINT: If the gas does not leak out even after the gas plug has
been loosened 2 turns, repeat the operation, turning the gas
plug a half turn to the left or right.

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)

BR–163

TROUBLESHOOTING

How to proceed with troubleshooting
Perform troubleshooting in accordance with the procedure on the following page.

CUSTOMER PROBLEM ANALYSIS

Using the customer problem analysis check sheet for reference, ask the customer in as much detail as
possible about the problem.

CHECK AND CLEAR THE DIAGNOSTIC TROUBLE CODES (PRECHECK)

If the TRAC indicator light lights up, and the TRAC control does not operate, the ECU stores diagnostic
trouble codes corresponding to the problem in memory.
Before confirming the trouble, first check the diagnostic trouble code for any malfunction codes stored in
memory. When there are malfunction codes, make a note of them, then clear them and proceed to “

Problem Symptom Confirmation”.

PROBLEM SYMPTOM CONFIRMATION,

SYMPTOM SIMULATION

Confirm the problem symptoms. If the problem does not reoccur, simulate the problem by initially checking
the circuits indicated by the diagnostic trouble code in step

, using “Problem simulation method”.

DIAGNOSTIC TROUBLE CODE CHECK

Check the diagnostic trouble codes. If a malfunction code is output, proceed to “

Diagnostic Trouble

Code Chart”.
If the normal code is output, proceed to “

Problem Symptoms Chart”.

Be sure to proceed to “

diagnostic Trouble Code Chart” after steps

and

are completed.

If troubleshooting is attempted only by following the malfunction code stored in the memory, errors could
be made in the diagnosis.

DIAGNOSTIC TROUBLE CODE CHART

If a malfunction code is confirmed in the diagnostic trouble code check, proceed to the inspection proce-
dure indicated by the matrix chart for each diagnostic trouble code.

PROBLEM SYMPTOMS CHART

If the normal code is confirmed in the diagnostic trouble code check, perform inspection in accordance with
the inspection order in the problem symptoms chart.

CIRCUIT INSPECTION

Proceed with diagnosis of each circuit in accordance with the inspection order confirmed in

and

.

Determine whether the cause of the problem is in the sensor, actuators, wire harness and connectors or
the ECU.

SENSOR CHECK

Use the ABS warning light to check if each of the signals from speed sensors is being input correctly to
the ECU. Instructions for this check are given in the circuit inspection.

[10] REPAIRS

After the cause of the problem is located, perform repairs by following the inspection and replacement pro-
cedures in this manual.

[11] CONFIRMATION TEST

After completing repairs, confirm not only that the malfunction is eliminated, but also conduct a test drive
to make sure the entire TRAC system is operating correctly. And also check the ABS is operating correctly.

BR–166

–

BRAKE SYSTEM

TRACTION CONTROL SYSTEM (TRAC)