1991 LEXUS SC400 brake

2. HYDRAULIC CONTROL SYSTEMThe hydraulic control system is composed of the oil pump, the valve body, the solenoid valves, the accumu-
lators, the clutches and brakes, as well as the fluid passages which connect al\
l of these components.
Based on the hydraulic pressure created by the oil pump, the hydraulic control system governs the hydrau-
lic pressure acting on the torque converter clutch, clutches and brakes \
in accordance with the vehicle driv-
ing conditions.
There are 4 solenoid valves on the valve body.
The No.1 and No.2 solenoid valves are turned on and off by signals from the ECM to operate the shift
valves, and change the gear shift position.
The No.3 solenoid valve is operated by signals from the ECM to engage or di\
sengage the lock±up clutch
of the torque converter clutch.
The No.4 solenoid valve is operated by signals from the ECM to control the \
engagement speed and reduce
gear shift shock.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION OPERATIONAT±7
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EQUIPMENT
AT06V±05\
 \
Feeler gauge Check major clearance\
 
\

\
Vernier calipers
 

Check length of second coast brake
piston rod.
\
 
\

\
Dial indicator or dial indicator with magnetic baseCheck piston stroke and end play of
the output shaft.
\
 
\

\
Dial indicator with magnetic baseCheck inside diameter of major
bushing.
\
 \
Straight edgeCheck side clearance of oil pump.
\
 \
Torque wrench
\
 
\

\
Cylinder gaugeCheck inside diameter of the trans-
mission case rear bushing.
\
 \
Voltmeter
\
 \
Ammeter(A)
\
 \
Ohmmeter
LUBRICANT
AT0GW±03
 Item Capacity Classification
 Automatic transmission fluid
 Dry fill 8.2 liters (8.7 US qts, 7.2 lmp. qts) ATF Type T±II or equivalent
 Drain and refill 1.9 liters (2.0 US qts, 1.7 lmp. qts) 
SSM (SPECIAL SERVICE MATERIALS)
AT06X±03
\
 \
08826±00090 Seal Packing 1281, Transmission case X Oil pan
\
 
\

\

THREE BOND 128\
1 or equivalentTransmission case X Extension
housing
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION PREPARATIONAT±13
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ELECTRONIC CONTROL COMPONENTS
INSPECTION
AT0GM±02
1. INSPECT SHIFT LOCK CONTROL ECMUsing a voltmeter, measure the voltage at each terminal.
 Connector Terminal\
 \
Measuring condition Voltage (V)  ACC±E\
 \
IG SW ACC position 10±14 


 

IG±E\
 
\

\
IG SW ON position 

10±14
 A STP±E\
 \
Depress brake pedal 10±14
 
A
 \
 \


IG SW ACC position and P position 0
  KLS±E\
 \
 R, N, D, 2, L, position 7.5±11
  \
 \
 R, N, D, 2, L position (after one second) 6±9.5
  \
 \

IG SW ON position and P position 0
 
B
 
SLS
± SLS 
\
 \
 Depress brake pedal 8±13.5 B SLS
± SLS \
 \
 Depress brake pedal (after 20 seconds) 6±8.5 


 


\
 
\

\

R, N, D, 2, L position 

0
  P1P\
 \


IG SW ON, P position and depress brake pedal 0
 C 
P1±P
\
 \
 R, N, D, 2, L position 9±13.5
 C P2±P\
 \

IG SW ACC position and P position 9±13.5
  P2±P\
 \
 R, N, D, 2, L position 0
2. INSPECT SHIFT LOCK SOLENOID
(a) Disconnect the solenoid connector.
(b) Usin g an oh mme te r, me a su re th e re sista n ce be twe e n
terminals.
Standard resistance:
20±28

If resistance value is not as specified, replace the solenoid.
(c) Apply the battery positive voltage between terminals. At this time, confirm that the solenoid operates.
If solenoid operation is not as specified, replace solenoid.
AT±28
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION SHIFT LOCK SYSTEM
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2. INSPECT BRAKE WARNING LIGHT(a) Disconnect the connector from the brake fluid warningswitch.
(b) Release the parking brake pedal.
(c) Connect terminals on the wire harness side of the level warning switch connector.
(d) Start the engine, check that the warning light lights up.
If the warning light does not light up, test the bulb or wire har-
ness.
(Parking Brake Switch)
REMOVAL AND INSTALLATION OF PARKING
BRAKE SWITCH
1. REMOVE PARKING BRAKE SWITCH
(a) Remove the driver's seat.
(See page BO±58)
(b) Disconnect the connector and remove switch.
2. INSTALL PARKING BRAKE SWITCH For installation follow the removal procedure in reverse.
INSPECTION OF PARKING BRAKE SWITCH
1. INSPECT PARKING BRAKE SWITCH
(a) Check that there is continuity between terminal andswitch body with the switch ON (switch pin released).
(b) Check that there is no continuity between terminal and switch body with the switch OFF (switch pin pushed in.)
If continuity is not as specified, replace the switch or inspect
ground point.
2. INSPECT BRAKE WARNING LIGHT (a) Disconnect the connector from the parking brake switchand brake fluid warning switch.
(b) Ground terminal on the wire harness side connector.
(c) Start the engine, check that the warning light lights up.
If the warning light does not light up, test the bulb or inspect
wire harness.
BE±116
±
BODY ELECTRICAL SYSTEM Combination Meter
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CUSTOMER PROBLEM ANALYSIS CHECK SHEET
POWER SEAT Check Sheet
Inspector 's
Name :
 


 


 

Registration No.
 


 

Customer 's Name
 


 

Registration Year
 

//
 


 


 

Frame No.
 


 

Date Vehicle
Brought In 

//
 

Odometer Reading
 

Km
Miles
 

Condition of
Problem
 

Date Problem
Occurrence\
 

\
//
 



Problem
Occurrence 



How Often does
Problem Occur?
\
 





Continuous
Intermittent ( times a day)
 




 






Manual Function
does not operate
\
 



\



Slide
Front Vertical

Rear Vertical
Reclining
Lumbar Support
 








Symptoms
 










Return Function
does not operate\
 







\



Slide
Front Vertical

Rear Vertical
Reclining

Does not operate in any conditions

Only with key inserted

Only with key not inserted

Only with memory & return switch 1 or 2
 \
 \

Memory function does not operate. 


\
 
\

\


Position return function does not stop when brake pedal is depressed.
For ªReturn function does not operateº malfunctions, check the ret\
urn operation of the items below.
 


Ch k It
 

Tilt & Telescopic
\
 

\


OK
NG
 


Check Item 

Outer Mirror
\
 

\


OK
NG
BE±270±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
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P11±17 SO B Signals between power seat ECU & tilt 0Ve12 V   B 
Signals between ower seat ECU & tilt
telescopic ECU 0 V e12 V
 P11±18 SGND BR±B Always Below 1 V
 P10±1 GND W±B Always Below 1 V
 P10±2 eP10±1 SLD+ eGND Le W±B Seat moved forward using slide SW 10±14 V
    Others Below 1 V
 

P10±3
eP10±1
 

RCL+
eGND
 

Y±R
eW±B
 


Seat moved forward using reclining
SW 

10±14 V
    Others Below 1 V
 P10±4
eP10±1 FRV+ eGND L±Y eW±B Seat raised using front vertical SW 10±14 V
    Others Below 1 V
 P10±5 +B L±W Always 10±14 V P10±6 eBody Ground STOP eBody Ground Ge W Brake pedal depressed 10±14 V    Others (Several
or less) Below 1 V P10±7 IG B±R Ignition SW ON 10±14 V P10±8 GND2 W±B Always Below 1 V P10±9 eP10±1 SLD± eGND L±B eW±B Seat moved to rear using slide SW 10±14 V    Others Below 1 V 
P10±10 eP10±1
 
RCL± eGND
 
Y±B eW±B
 
Seat moved to rear using reclining SW
 
10±14 V    
Others
 
Below 1 V 

P10±11
eP10±1
 

FRV±
eGND
 

L±R
eW±B
 

Seat lowered using front vertical SW
 

10±14 V
    Others Below 1 V
 P10±12
eP10±1 RRV± eGND Y±LW±B Seat lowered using rear vertical 10±14 V
    Others Below 1 V
 P10±13 eP10±1 RRV+ eGND Y±L eW±B Seat raised using rear vertical 10±14 V
    Others Below 1 V
 P10±14 +B2 L±W Always 10±14 V
 P10±15 eBody Ground Pe Body Ground GR Shift lever in ºPº with IG ON 10±14 V
    Others (10
or less) Below 1 V
 P10±16 ±± ±± ±± ±±
BE±274±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
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Check stop light operation.NG
OK OK
NG Check stop light circuit
(See page
BE±64).
Proceed to next circuit inspection
shown on matrix chart
(See page
BE±276).
Check voltage between terminals STOP
of ECU connector and body ground.
Check and repair harness and connec-
tor between ECU and stop light switch.
WIRING DIAGRAM
Stop Light Circuit
CIRCUIT DESCRIPTION
The stop light switch sends a brake ON of Off signal to the ECU. When the ECU receives a brake ON signal
it prohibits return of the seat.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BE±298±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)
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OKNG
NGOK
INSPECTION PROCEDURE
1Check stop light operation.
Check that the stop light comes on when the brake pedal is depressed, and turn\
s off when the pedal
is released.C
Check stop light circuit. (See page BE±64).
2Check voltage between terminal STOP of ECU connector and body ground.
C
OK
Hint
PRemove ECU with connectors still connected.
Measure voltage between terminal STOP of ECU and
body gr ound when the brake pedal is depressed and re-
leased.
Brake pedal Voltage
Depressed 10 ± 14 V Released Below 1 V
Proceed to next circuit inspection shown on matrix chart
(See page BE±276).
Check and repair harness and connector between
ECU and stop light switch.
±
BODY ELECTRICAL SYSTEM Power Seat Control System (Driver's Seat)BE±299
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