1991 LEXUS SC400 sensor

DTC45, 46Main Throttle Position Sensor Circuit
CIRCUIT DESCRIPTION
This circuit is not directly related to the TRAC control, but as it has an i\
nfluence on TRAC control when trouble
occurs in this circuit, it is used to switch off the TRAC system as a fail safe function.
DTC No.DTC Detecting ConditionTrouble Area
45
Either of the following (1) and (2) continues for 0.12
sec.:
(1) IDL switch of main throttle position sensoris ON.
(2) Input voltage of TRAC ECU terminal VTH:1.45 V or
more.
Main throttle position sensor

Open in VTH circuit

Short in IDL1 circuit

ECM

TRAC ECU
46
Either of the following (1) or (2) continues for0.12 sec.:
(1) Input voltage of TRAC ECU terminal VTH:4.3 V or
more.
(2) Input voltage of TRAC ECU terminal VTHwhile
IDL1 switch is OFF: 0.2 V or less
Main throttle position sensor

Short in VTH circuit

ECM

TRAC ECU
BR±200±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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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
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OKNG
10Check main throttle position sensor (See page EG±609 or EG±389 ).
Adjust or replace main throttle position sensor (See
page EG±333 or EG±205).
Check and replace ECM.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±207
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DTC47, 48Sub±Throttle Position Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the opening angle of the sub±throttle valve and sends the appropriate signals to the ECU.
If a trouble signal is input, the ECU prohibits TRAC control.
DTC No.DTC Detecting ConditionTrouble Area
47
When any of the following (1) through (3) is detected:
(1) Deviation of 5 steps or more to the closedside of the idle step during sub±throttleinitial check.
(2) Voltage at terminal IDL2 switch is OFF evenafter sub±throttle is driven to fully closedposition during
sub±throttle initial check 4.
(3) Voltage at terminal VSH is 1.45 V or morefor at least 0.15 sec. while idle switch is ON.

Sub±throttle position sensor

Open or short in IDL2 circuit

ECM

TRAC ECU
48
Either of the following (1) or (2) continues for atleast
0.12 sec.
(1) Input voltage of TRAC ECU terminal VSH:4.3 V or more.
(2) Input voltage of TRAC ECU terminal VSHis 0.2 V or less while IDL2 switch OFF.

Sub±throttle position sensor

Open or short in VSH circuit

ECM

TRAC ECU
BR±208±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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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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OKNG
10Check sub±throttle position sensor (See page EG±609 or EG±389 ).
Adjust or replace sub±throttle position sensor (See page
EG±333 or EG±205 ).
Check and replace ECM.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±215
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TORQUE SPECIFICATIONS
BR03B±0G\
 
\

\
Part tightened
 

N
Vm
 

kgf
Vcm
 

ft
Vlbf
\
 \
Master cylinder x Piston stopper bolts 10 100 7
\
 \
Master cylinder x Reservoir 1.7 17.5 15.2 in. Vlbf
\
 
\

\
Master cylinder x Brake booster 

13 

130 

9
\
 \
Brake tube union nut 15 155 11
\
 \
Brake booster clevis lock nut 25 260 19
\
 \
Brake booster x Pedal bracket 15 150 11\
 
\

\
Bleeder plug (TRAC actuator and TRAC accumulator)
 

8.3
 

85
 

74 in.
Vlbf
\
 \
Bleeder plug 11 11 0 8
\
 \
Front disc brake torque plate x Steering knuckle 11 8 1,200 87
\
 \
Front disc brake cylinder installation bolt 34 350 25\
 
\

\
Front disc brake cylinder x Flexible hose bolt
 

30
 

310
 

22
\
 \
Rear disc brake torque plate x Axle carrier 104 1,065 77
\
 \
Rear disc brake cylinder installation bolt 34 350 25
\
 
\

\
Rear disc brake x Flexible hose union bolt 

30 

310 

22
\
 \
Parking brake lever x Floor 59 600 43
\
 \
Parking brake cable No.1 x Floor 9 80 69 in.
Vlbf
\
 \
Parking brake cable retainer x Floor 5.4 55 48 in. Vlbf\
 
\

\
Parking brake cable clamp x Floor
 

19
 

190
 

14
\
 \
ABS actuator x Actuator bracket 5.4 55 48 in.
Vlbf
\
 \
ABS actuator bracket x Body 19 195 14
\
 
\

\
Front speed sensor installation bolt 

7.8 

80 

69 in.
Vlbf
\
 \
Rear speed sensor installation bolt 7.8 80 69 in. Vlbf
\
 \
TRAC pump bracket x Body 19 195 14
\
 \
TRAC pump or accumulator x Union bolt 46 465 34
BR±230±
BRAKE SYSTEM SERVICE SPECIFICATIONS
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BR0F2±02
SPEED SENSOR
SPEED SENSOR REMOVAL AND
INSTALLATION
Remove and install the parts, as shown.
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±71
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