ignition LEXUS SC300 1991 Service Repair Manual

NGOK
OKNG
8Check voltage between terminal IDL2 of TRAC ECU connector and body ground with TRAC ECU
connector disconnected.
C
OK
Hint
P1. Disconnect the TRAC ECU connector.
2. Turn ignition switch on.
Measure voltage between terminal IDL2 of TRAC ECM
connector and body ground, when the sub±throttle
valve is fully closed and fully opened.
Check and replace TRAC ECU.
9Check for open and short in harness and connector between terminal IDL2 of TR\
AC ECU and
ECM (See page IN±33).
Repair or replace harness or connector.
BR±214
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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IN±29).
WIRING DIAGRAM
DTC49Engine Communication Circuit
CIRCUIT DESCRIPTION
This circuit is used to send ignition timing retard request signals from the TRAC ECU to\
the ECM in order to retard
the engine ignition timing.
DTC No.DTC Detecting ConditionTrouble Area
49TR2 output voltage differs from TR2 monitorvoltage in
TRAC ECU.
Open or short in TR2 circuit

ECM

TRAC ECU
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BR±216±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal TR2 of TRAC ECU and body ground.
C
OK
Hint
P1. Disconnect TRAC ECU connector.
2. Turn ignition switch on.
Measure voltage between terminal TR2 of TRAC ECU
and body ground.
Voltage: 8 ± 14 V
Check and replace TRAC ECU.
2Check for open and short in harness and connector between TRAC ECU and E\
CM (See page
IN±29).
Repair or replace harness or connector.
Check and replace ECM.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±217
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OKNG
NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals ABSO, BRC, BRP of TRAC ECU and body ground.
C
OK
Hint
PRemove TRAC ECU with connectors still connected.
Measure voltage between terminals ABSO, BRC, BRP
of TRAC ECU and body ground when ignition switch is
turned ON.
Voltage: ABSO, BRC: 6 ± 14 VBRP: About 7 V (Pulse)\
(Reference)
Check and replace TRAC ECU.
2Check voltage between terminals ABSO, BRC, BRP or TRAC ECU and body ground wi\
th TRAC
ECU connector is disconnected.
C
OK
Hint
PDisconnect TRAC ECU connector.
Measure voltage between terminals ABSO, BRC, BRP
or TRAC ECU connector and body ground when ignition
switch is turned ON.
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±221
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NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals Tc and E1 of DLC 2 or DLC 1.
C
OK
PTurn ignition switch ON.
Measure voltage between terminals TC and E1 of DLC
2 or DLC 1.
Voltage: 10 ± 14 V
Proceed to next circuit inspection shown on problem
symptoms chart (See page BR±160).
2Check for open and short in harness and connector between ABS & TRAC ECU, TRAC\
ECU and
DLC 2 (or DLC 1), DLC 2 (or DLC 1) and body ground (See page IN±33).
Repair or replace harness or connector.
Check and replace TRAC ECU.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±227
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MASTER CYLINDER
MASTER CYLINDER REMOVAL
BR0EF±03
1. w/ TRAC:DRAIN OUT HIGH PRESSURE FLUID
(a) C onnect a vinyl tube to the bleeder plug of the TRAC
actuator, then loosen the bleeder plug with the ignition switch
in the OFF position.
CAUTION: The fluid is under high pressure, and could spray
out with great force, so exercise caution.
(b) Tighten the plug when fluid stops flowing out.
2. DISCONNECT LEVEL WARNING SWITCH CONNECTOR
3. DRAW OUT FLUID WITH SYRINGE
NOTICE: Do not let brake fluid remain on a painted surface.
Wash it off immediately.
4. DISCONNECT BRAKE LINES Using SST, disconnect the brake lines from the master cylin-
der.
SST 09023±00100
BR±12
±
BRAKE SYSTEM MASTER CYLINDER
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BRAKE BOOSTER
BRAKE BOOSTER REMOVAL
BR0EK±03
1. w/ TRAC:DRAIN OUT HIGH PRESSURE FLUID
(a) C onnect a vinyl tube to the bleeder plug of the TRAC
actuator, then loosen the bleeder plug with the ignition switch
in the OFF position.
CAUTION: The fluid is under high pressure, and could
spray out with great force, so exercise caution.
(b) Tighten the plug when fluid stops flowing out.
2. REMOVE FOLLOWING PARTS: wMaster cylinder
(See page BR±12)
w w/ TRAC:
TRAC pump assembly
(See page BR±162)
w Vacuum hose
w Clip and return spring
BR±18
±
BRAKE SYSTEM BRAKE BOOSTER
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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
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
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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)
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DTC11, 12ABS Solenoid Relay Circuit
CIRCUIT DESCRIPTION
This relay supplies power to each ABS solenoid. After the ignition switch is\
turned on, if the initial check is OK,
the relay goes on.
DTC No.DTC Detecting ConditionTrouble Area
11
Conditions (1) and (2) continue for 0.2 sec. or more:
(1) ABS solenoid relay (SR) terminal voltage: Battery
positive voltage
(2) Solenoid relay monitor (AST) terminal voltage: 0V
ABS solenoid relay

Open or short in ABS solenoid relay circuit

ECU
12
Conditions (1) and (2) continue for 0.2 sec. or more:
(1) ABS solenoid relay (SR) terminal voltage: 0V
(2) Solenoid relay monitor (AST) terminal voltage: Bat- tery positive voltage
ABS solenoid relay

B+ short in ABS solenoid relay circuit

ECU
Fail safe function: If trouble occurs in the solenoid relay circuit, th\
e ECU cuts off current to the solenoid
relay and prohibits ABS control.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BR±94±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
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