ABS LEXUS SC400 1991 Service Service Manual

(e) Push the POWER SWITCH, and check that the brake pedalcan not be depressed.
NOTICE: Do not keep the MAIN push switch pushing more
than 10 seconds.
(f) Re le a se th e switch , an d ch e ck th a t th e p edal can be
depressed.
(g) Push and hold in the MOTOR switch for a few seconds, and check that the pedal returns.
(h) Release the brake pedal.
(i) Push and hold in the MOTOR switch for a few seconds.
(j) Depress the brake pedal and hold it for about 15 seconds. As
you hold the pedal down, push the SUB MOTOR switch for
a few seconds. Check that the brake pedal does not pulsate.
5. INSPECT FOR OTHER WHEELS
(a) Turn the MAIN selector switch to the ªFRONT LHº position.
(b) Repeat (c) to (j) of step 4, checking the actuator operation in the same way.
(c) Also, inspect the ªREAR RHº and ªREAR LHº positions following the same procedure.
HINT: When inspecting the ªREAR LHº position, push the
REAR LH switch instead of the POWER SWITCH. This
makes it possible to inspect wherever the selector switch
position indicates.
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BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±69
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6. PUSH MOTOR SWITCHPush and hold in the MOTOR switch for a few seconds.
7. DISCONNECT ACTUATOR CHECKER (SST) FROM ACTUATOR
(a) Disconnect the actuator checker (SST) and sub±wire
harnesses (SST) from the actuator.
SST 09990±00150, 09990±00163, and 09990±00250
(b) Connect the actuator connectors.
(c) Clear the diagnostic trouble codes. (See page BR±77)
BR±70
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BR0F2±02
SPEED SENSOR
SPEED SENSOR REMOVAL AND
INSTALLATION
Remove and install the parts, as shown.
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BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±71
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TROUBLESHOOTING
How to proceed with troubleshooting
Perform troubleshooting in accordance with the procedure on the followin\
g pages.

CUSTOMER PROBLEM ANALYSIS
Using the customer problem analysis check sheet for reference, ask the c\
ustomer in as much detail as
possible about the problem.
CHECK AND CLEAR THE DIAGNOSTIC TROUBLE CODES (PRECHECK)
If the ABS warning light lights up, and the ABS does not operate, the ECU \
stores diagnostic trouble codes
corresponding to the problem in memory.
Before confirming the trouble, 1st check the diagnostic trouble codes for any \
malfunction codes stored in
memory. When there are malfunction codes, make a note of them, then clear them \
and proceed to ª  Prob-
lem Symptom Confirmationº.
 PROBLEM SYMPTOM CONFIRMATION,  SYMPTOM SIMULATION
Confirm the problem symptoms. If the problem does not reoccur, simulate the problem by initially checking
the circuits indicted by the diagnostic trouble code in step , using ªProblem simulation methodº.
 DIAGNOSTIC TROUBLE CODE CHECK
Check the diagnostic trouble codes. If a malfunction code is output, proceed \
to ª  Diagnostic Trouble
Code Chartº. If the normal code is output, proceed to ª  Problem Symptoms Chartº. Be sure to proceed
to ª  diagnostic Trouble Code Chartº after steps and  are completed.
If troubleshooting is attempted only by following the malfunction code sto\
red 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, perf\
orm 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.
\b SENSOR CHECK
Use the ABS warning light to check if each of the signals from speed sensors are 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 i\
nspection 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 ABS system is operating correctly. (In vehicles with the TRAC system, also check
the TRAC system.)
BR±72
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BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
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P. BR±74
P. BR±76 ± BR±79
P. BR±76
P.BR±78 P. BR±82
P. BR±94
± BR±151P. BR±152
P.
IN±24
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BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±73
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CUSTOMER PROBLEM ANALYSIS CHECK SHEET
BR±74±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
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±MEMO±
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BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±75
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DIAGNOSIS SYSTEM
INDICATOR CHECKWhen the ignition switch is turned on, check that the ABS
warning light goes on for 3 seconds.
HINT: If the indicator check result is not normal, proceed to
trouble shooting for the ABS warning light circuit (see page
BR±144 ).
DIAGNOSTIC TROUBLE CODE CHECK
1. Turn the ignition switch to ON.
2. Disconnect the Short Pin from DLC1.
3. Using SST, connect terminals Tc and E1 of DLC2 or DLC1. SST 09843±18020
4. Read the diagnostic trouble code from the ABS warning light
on the combination meter.
HINT: If no code appears, inspect the diagnostic circuit or
ABS warning light circuit (See page BR±148 or BR±144 ).
As an example, the blinking patterns for normal code and
codes 11 and 21 are shown on the left.
5. Codes are explained in the code table on page BR±78.
6. After completing the check, disconnect terminals Tc and E1, and turn off the display.
If 2 or more malfunctions are indicated at the same time, the
lowest numbered diagnostic trouble code will be displayed
first.
BR±76
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ECU DATA MONITOR USING LEXUS HAND±HELD TESTER
1. Hook up the LEXUS hand±held tester to the DLC2.
2. Monitor the ECU data by following the prompts on the testerscreen.
HINT: LEXUS hand±held tester has a ªSnapshotº function
which records the monitored data.
Please refer to the LEXUS hand±held tester operator's
manual for further details.
DIAGNOSTIC TROUBLE CODE CLEARANCE
1. Using SST, connect terminals Tc and E1 of DLC2 or DLC1. SST 09843±18020
2. IG switch ON.
3. Clear the diagnostic trouble codes stored in ECU by depressing the brake pedal 8 or more times within 3 seconds.
4. Check that the warning light shows the normal code.
5. Remove the SST from the terminals of DLC2 or DLC1.
6. Connect the Short Pin to DLC1.
HINT: Cancellation can also be done by removing the DOME
fuse, but in this case, other memory systems will also be can-
celled out.
ECU TERMINAL VALUES MEASUREMENT USING LEXUS BREAK±OUT±BOX AND LEXUS HANDHELD TESTER
1. Hook up the LEXUS hand±held tester and LEXUS
break±out±box to the vehicle.
2. Read the ECU input/output values by following the prompts on the scan tool screen.
HINT: LEXUS hand±held tester has a ªSnapshotº function.
This records the measured values and is effective in the diag-
nosis of intermittent problems.
Please refer to the LEXUS hand±held tester/LEXUS break±
out±box operator's manual for further details.
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BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±77
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DIAGNOSTIC TROUBLE CODE CHART
If a malfunction code is displayed during the diagnostic trouble code chec\
k, check the circuit listed for that
code, in the table below and proceed to the relevant page.
HINT: Using SST 09843±18020, connect the terminals Tc and E1, and remove the short pin.
BR±94BR±98
BR±102
BR±106BR±110
BR±114
BR±118 BR±94
BR±98
BR±102
BR±106
BR±110BR±110
BR±110
BR±114
BR±114
BR±118
BR±118
BR±118
BR±78
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