Page 1046 of 4087
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.
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±77
WhereEverybodyKnowsYourName
Page 1047 of 4087
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
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
WhereEverybodyKnowsYourName
Page 1048 of 4087
BR±118
BR±122BR±125
BR±126 BR±130
BR±132
BR±134
BR±138 BR±140
BR±118
BR±134
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±79
WhereEverybodyKnowsYourName
Page 1049 of 4087
SPEED SENSOR SIGNAL CHECK
1. Turn the ignition switch to OFF.
2. Using SST, connect terminals Ts and E1 of DLC1.SST 09843±18020
3. Start the engine.
4. Check that the ABS warning light blinks. HINT: If the ABS warning light does not blink, inspect the ABS
warning light circuit (see page BR±144).
5. Drive vehicle straight forward. HINT: Drive vehicle faster than 45 km/h (28 mph) for several
seconds.
6. Stop the vehicle.
7. Using SST, connect terminals Tc and E1 of DLC1.
SST 09843±18020
8. Read the number of blinks of the ABS warning light. HINT: See the list of diagnosis trouble codes shown on the
next page.
If every sensor is normal, a normal code is output (A cycle of
0.25 sec. on and 0.25 sec. OFF is repeated).
If 2 or more malfunction are indicated at the same time, the
lowest numbered code will be displayed 1st.
9. After performing the check, disconnect terminals Ts and E1,Tc and E1 of DLC1, and ignition switch turned off.
BR±80
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
WhereEverybodyKnowsYourName
Page 1050 of 4087
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 of Speed Sensor Check Function
Code No.\
\
Diagnosis Trouble Area
71
\
\
Low output voltage of right front speed sensor
Right front speed sensor
71
\
\
Low output voltage of right front speed sensor
Sensor installation
72\
\
Low output voltage of left front speed sensor
Left front speed sensor
72\
\
Low output voltage of left front speed sensor
Sensor installation
73
\
\
Low output voltage of right rear speed sensor
Right rear speed sensor
73\
\
Low output voltage of right rear speed sensor
Sensor installation
74
\
\
Low output voltage of left rear speed sensor
Left rear speed sensor 74\
\
Low output voltage of left rear speed sensor
Sensor installation
75
\
\
Abnormal change in output voltage of right front speed
sensor
Right front speed sensor rotor
76
\
\
Abnormal change in output voltage of left front speed
sensor
Left front speed sensor rotor
77
\
\
Abnormal change in output voltage of right rear speed
sensor
Right rear speed sensor rotor
78\
\
Abnormal change in output voltage of left rear speed
sensor
Left rear speed sensor rotor
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±81
WhereEverybodyKnowsYourName
Page 1051 of 4087
![LEXUS SC400 1991 Service Repair Manual
PROBLEM SYMPTOMS CHART
If a normal code is displayed during the diagnostic trouble code check but\
the problem still occurs, check
the circuits for each problem symptom in the order given in the tab](/manual-img/36/57051/w960_57051-1050.png "LEXUS SC400 1991 Service Repair Manual
PROBLEM SYMPTOMS CHART
If a normal code is displayed during the diagnostic trouble code check but\
the problem still occurs, check
the circuits for each problem symptom in the order given in the tab")
PROBLEM SYMPTOMS CHART
If a normal code is displayed during the diagnostic trouble code check but\
the problem still occurs, check
the circuits for each problem symptom in the order given in the table below\
and proceed to the page for
troubleshooting.
Symptoms\
\
Inspection Circuit See page
ABS does not oper-
ate.\
\
\
Only when 1.±4. are all normal and the problem is still occurring,
replace the ABS (& TRAC) ECU.
BR±76
\
\
\
1. Check the diagnostic trouble code, reconfirming that the nor-
mal code is output.
BR±122
BR±118
\
\
2. IG Power Source Circuit. BR±65 or 68
\
\
\
3. Speed sensor circuit.
\
\
\
\
4. Check the ABS actuator with a checker.
If abnormal, check the hydraulic circuit for leakage (see page
BR±138).
ABS does not oper-
ate efficiently.\
\
\
Only when 1.±4. are all normal and the problem is still occurring,
replace the ABS (& TRAC) ECU.
BR±76
\
\
\
1. Check the diagnostic trouble code, reconfirming that the nor-
mal code is output.
BR±118
BR±142
\
\
2. Speed sensor circuit. BR±65
or 68
\
\
3. Stop light switch circuit
\
\
\
\
4. Check the ABS actuator with a checker.
If abnormal, check the hydraulic circuit for leakage (see page
BR±138).
ABS warning light ab-
normal.\
\
\
1. ABS warning light circuit.
BR±144
\
\
2. ABS (& TRAC) ECU.
Diagnostic trouble
code check cannot
be performed.\
\
\
\
Only when 1. and 2. are all normal and the problem is still occur-
ring, replace the ABS (& TRAC) ECU.
BR±144
\
\
1. ABS warning light circuit BR±148
\
\
\
2. To terminal circuit.
Speed sensor signal
check cannot be per-
formed.\
\
\
1. Ts terminal circuit.
BR±150
\
\
\
2. ABS (& TRAC) ECU.
BR±82±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
WhereEverybodyKnowsYourName
Page 1052 of 4087
±MEMO±
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±83
WhereEverybodyKnowsYourName
Page 1053 of 4087
LOCATION OF CONNECTORS
Location of Connectors in Engine Compartment
BR±84±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
WhereEverybodyKnowsYourName
![LEXUS SC400 1991 Service Repair Manual
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 pag](/manual-img/36/57051/w960_57051-1046.png "LEXUS SC400 1991 Service Repair Manual
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 pag")
