ignition switch LEXUS SC400 1991 Service Repair Manual

OKNG
NGOK
OKNG
INSPECTION PROCEDURE
1Check battery positive voltage.
Voltage: 10 ± 14 VCOK
Check and repair the charging system.
2Check voltage between terminals IG and GND of TRAC ECU connector.
C
OK
P1. Remove TRAC ECU with connectors still con-nected.
2. Turn ignition switch on.
Measure voltage between terminals IG and GND of
TRAC ECU connector.
Voltage: 10 ± 14 V
Check and replace TRAC ECU.
3Check continuity between terminals GND of TRAC ECU connector and body gr\
ound.
C
OK
Measure resistance between terminal GND or TRAC
ECU connector and body ground.
Resistance: 1
or less
Repair or replace harness or connector.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±193
WhereEverybodyKnowsYourName

NGOK
NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal BRFA of TRAC ECU and body ground.
C
OK
P1. Remove TRAC ECU with connectors still con-nected.
2. Turn ignition switch ON.
Measure voltage between terminal BRFA of TRAC ECU
and body ground.
Voltage: About 6 V (Pulse)
Check and replace TRAC ECU.
2Check voltage between terminal BRFA of TRAC ECU and body ground with TRAC ECU connec-
tor is disconnected.
C
OK
Hint
PDisconnect TRAC ECU connector.
Measure voltage between terminal BRFA of TRAC ECU
connector and body ground.
Measure voltage within 8 seconds from the time TRAC
ECU connector is disconnected.
Voltage: See step 1.
Check and replace TRAC ECU.
3Check for open and short in harness and connector between ABS & TRAC ECU and TRAC ECU
(See page IN±33).
Repair or replace harness or connector.
Check and replace ABS & TRAC ECU.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±197
WhereEverybodyKnowsYourName

OKNG
OKNG
INSPECTION PROCEDURES
1Check for open and short in harness and connector between terminal NEO of TRA\
C ECU and
terminal NEO of ECM (See page IN±33).
Repair or replace harness or connector.
2Check voltage between terminal NEO of TRAC ECU and body ground.
C
OK
P1. Remove TRAC ECU with connectors still con-
nected.
2. Turn ignition switch on.
Measure voltage between terminal NEO of TRAC ECU
and body ground for the engine conditions below.
Check and replace TRAC ECU or ECM.
If the same code is still output after the diagnostic code is deleted, che\
ck the contact condition of each
connection.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±199
WhereEverybodyKnowsYourName

NOYES
NGOK
OKNG
INSPECTION PROCEDURE
1Is diagnostic trouble code output for the engine?
Perform diagnostic trouble code check on page EG±523 or EG±305 .
Repair circuit indicated by the code output.
2Check voltage between terminal VTH of TRAC ECU and body ground.
C
OK
P1. Remove TRAC ECU with connectors still con-
nected.
2. Remove intake air duct.
3. Turn ignition switch on.
Measure voltage between terminal VTH of TRAC ECU
and body ground, when the main throttle valve is turned
from fully closed position to fully opened position by
hand
In addition, as the main throttle valve is turned, the
voltage should increase gradually w ith out interrup-
tion.
Go to step .
3Check for open and short in harness and connector between terminal VTH o\
f TRAC ECU and
terminal VTO1 of ECM (See page IN±33).
Repair or replace harness or connector.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±203
WhereEverybodyKnowsYourName

NGOK
NGOK
4Check voltage between terminal VTO1 of ECM and body ground with TRAC ECU connector dis-
connected.
C
OK
P1. Connect the Check Harness A. (See page EG±542
or EG±328 ).
2. Disconnect the TRAC ECU connector.
3. Turn ignition switch on.
Measure voltage between terminal VTO1 or ECM and
body ground, when the main thro ttle valve is fully closed
and fully opened.
Check and replace TRAC ECU.
5Check voltage of terminal VTA1 of ECM (See page EG±608 or EG±388 ).
Check and replace ECM.
BR±204
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
WhereEverybodyKnowsYourName

OKNG
NGOK
6Check for open and short in harness and connector between terminal VTA1 of ECM and main
throttle position sensor (See page IN±33
).
Repair or replace harness or connector.
Adjust or replace main throttle position sensor
(See page EG±333 or EG±205 ).
7Check voltage between terminal IDL1 of TRAC ECU and body ground.
C
OK
PTurn ignition switch on.
Measure voltage between terminal IDL1 of TRAC ECU
and body ground, when the main throttle valve is fully
closed and fully opened.
Check and replace TRAC ECU.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±205
WhereEverybodyKnowsYourName

NGOK
OKNG
8Check voltage between terminal IDL1 of TRAC ECU connector and body ground with TRAC ECU
connector disconnected.
C
OK
P1. Disconnect the TRAC ECU connector.
2. Turn ignition switch on.
Measure voltage between IDL1 of TRAC ECU connec-
tor and body ground, when the main throttle valve is fully
closed and fully opened.
Check and replace TRAC ECU>
9Check for open and short in harness and connector between terminal IDL1 of TR\
AC ECU and
ECM (See page IN±33).
Repair or replace harness or connector.
BR±206
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
WhereEverybodyKnowsYourName

NOYES
NGOK
OKNG
INSPECTION PROCEDURE
1Is diagnostic trouble code output for the engine?
Perform diagnostic trouble code check on page EG±523 or EG±305 .
Repair circuit indicated by the code output.
2Check voltage between terminal VSH or TRAC ECU and body ground.
C
OK
P1. Remove TRAC ECU with connectors still con-
nected.
2. Remove intake air duct.
3. Disconnect step motor connector.
4. Turn ignition switch on.
Measure voltage between terminal VSH or TRAC ECU
and body ground, when the sub±throttle valve is turned
from fully opened position to fully closed position.
In addition, as the sub±throttle valve is turned, the
voltage should increase gradually w ith out interrup-
tion.
Go to step
.
3Check for open and short in harness and connector between terminal VSH of TRAC ECU and
terminal VTO2 of ECM (See page IN±33).
Repair or replace harness or connector.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±211
WhereEverybodyKnowsYourName

NGOK
NGOK
4Check voltage between terminal VTO2 of ECM and body ground with TRAC ECU connector dis-
connected.
C
OK
P1. Connect the Check Harness A. (See page EG±562
or EG±328 ).
2. Disconnect the TRAC ECU connector.
3. Turn ignition switch on.
Measure voltage between terminal VTO2 of ECM and
body ground, when the sub±throttle valve is fully closed
and fully opened.
Check and replace TRAC ECU.
5Check voltage of terminal VTA2 of ECM (See page EG±608 or EG±388 ).
Check and replace ECM.
BR±212
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
WhereEverybodyKnowsYourName

OKNG
NGOK
6Check for open and short in harness and connector between terminal VTA2 of ECM and sub±
throttle position sensor (See page IN±33
)
Repair or replace harness or connector.
Adjust or replace sub±throttle position sensor
(See page EG±333 or EG±205 ).
7Check voltage between terminal IDL2 of TRAC ECU and body ground.
C
OK
PTurn ignition switch on.
Measure voltage between terminal IDL2 or TRAC ECU
connector and body ground, when the sub±throttle
valve is fully closed and fully opened.
Check and replace TRAC ECU.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±213
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