ect LEXUS SC300 1991 Service Repair Manual

SPECIFIED LINE PRESSURE
 
Condition
 
D positionkPa (kgf/cm2, psi)
 
R positionkPa (kgf/cm2, psi) 

Idling
 

382±441 (3.9±4.5, 55±64)
 

637±716 (6.5±7.3, 92±104) 

Stall
 

1,265±1,402 (12.9±14.3, 183±203)
 

1,726±2,060 (17.6±21.0, 250±299)
If the measured pressures are not up to specified values, recheck the thro\
ttle cable adjustment and perform
a retest.
EVALUATION
 Problem\
 \
Possible cause
 \
 \

Throttle cable out of adjustment If the measured values at all positions are higher.\
 \
 Throttle valve defective 


\

\

\

Regulator valve defective
 \
 \
 Throttle cable out of adjustment
 \
 \
 Throttle valve defective
 If the measured values at all positions are lower.\
 \
 Regulator valve defective
 \
 \
 Oil pump defective
 \
 \
 O/D direct clutch defective
 
Ifpressure is low in the Dposition only
\
 \
 D position circuit fluid leakage If pressure is low in the D position only.\
 \
 Forward clutch defective 


\

\

\

R position circuit fluid leakage
 If pressure is low in the R position only.\
 \
 Direct clutch defective
 \
 \
 First and reverse brake defective
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MEASURE ACCUMULATOR BACK PRESSURE
AT0QU±01
NOTICE:
Perform the test at normal operating fluid temperature 50±80 C (122±176 F).
 Be careful to prevent the oil pressure gauge hose from interfering with \
the exhaust pipe.
(a) Warm up the transmission fluid.
(b) Remove the test plug on the transmission case rear right side and connec\
t the oil pressure gauge SST.
SST 09992±00094
HINT: Connecting the oil pressure gauge will be made easier by moving the RH \
side head insulator aside.
(c) Remove the passenger side No.2 under cover and ECM protector.
(d) Connect the SST (check harness A) between ECM and connector of vehicle\
wire harness.
SST: 09990±01000
(e) Install one test lead probe into the terminal SLN of the ECM wire harnes\
s side connector and take care not to ground the other test lead probe.
HINT: Prepare test leads which are connected with an (approximately) 8 W l\
ight bulb.
AT±56
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(f) Fully apply the parking brake and chock the 4 wheels.
(g) Start the engine and check idling RPM.
(h) Keep your left foot pressed firmly on the brake pedal and shift into D p\
osition.
(i) Measure the accumulator back pressure.
(j) With the conditions the same as in (h), ground the other probe of the test\
lead which has one end insertedinto the terminal SLN of the ECM harness side connector, then measure the accumulator back pressure
again.
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SPECIFIED ACCUMULATOR BACK PRESSURE
 Condition if ECM terminal SLN Not ground kPa (kgf/cm2, psi) Ground kPa (kgf/cm2 , psi) 

Accumulator back pressure 

177±255 (1.8±2.6, 26±37) 

0
EVALUATION
 Problem\
 \
Possible cause \
 \

Throttle cable out of adjustment 

Th l t b k i t ifi d
\

\

\

Throttle valve defective
 The accumulator back pressure is not as specified
(high or low) when the terminal SLN is not ground.\
 \
 Solenoid modulator valve defective
 
(high or low) when the terminal SLN is not ground.
\
 \
 SLN solenoid valve defective
 \
 \
 Accumulator control valve defective
 


The accumulator back pressure does not become 0
kgf/cm2 when the terminal SLN is grounded.
\

\

\

SLN solenoid valve defective
AT±58±
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MANUAL SHIFTING TEST
AT0QV±01
HINT: With this test, it can be determined whether the trouble
is within the electrical circuit or is a mechanical problem in the
transmission.
1. DISCONNECT SOLENOID WIRE
2. INSPECT MANUAL DRIVING OPERATION Check that the shift and gear positions correspond with the
table below.
 Shift Position Gear Position
 D PositionO/D 2 Position3rd L Position1st 

R PositionReverse
 P PositionPawl Lock
HINT: If the L, 2 and D position gear positions are difficult to
distinguish, perform the following road test.
w
While driving, shift through the L, 2 and D positions.
Check that the gear change corresponds to the shift
position.
If any abnormality is found in the above test, the problem is
in the transmission itself.
3. CONNECT SOLENOID WIRE
4. CANCEL OUT DIAGNOSTIC TROUBLE CODE (See page AT±39)
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\
 

\


\

\

Trouble Area
 




O/D OFF
Light*1
Blinks
 




Memory*2
 




See
Page
\
 \
   
\
 \

Harness or connector between No. 1 vehicle speed sensor and ECM.   
\
 \

No. 1 vehicle speed sensor. 

 

 
AT±78\
 \

Combination meter.   AT±78
\
 \

ECM   
\
 \
   
\
 
\
\
 
\

\


Harness or connector between No.4 solenoid and ECM.
\
 \

No.4 solenoid.XAT±82
\
 \

ECM
\
 \

\
 \
   
\
 \

Harness or connector between No.2 vehicle speed sensor and ECM.   
\
 \

No.2 vehicle speed sensor.   AT±86\
 
\

ECM 

 

 
\
 
\

\

 


 


 


\
 \

\
 \


Harness or connector between No.1 solenoid and ECM.
\
 \

No.1 solenoid.AT±90
\
 \

ECM
\
 \

\
 \

\
 
\

Harness or connector between No.2 solenoid and ECM.\
 
\

\


No.2 solenoid.AT±90
\
 \

ECM
\
 \

\
 \

\
 \

Harness or connector between No.3 solenoid valve and ECM.
\
 \

No.3 solenoid valve.XAT±94\
 \

ECM\
 
\
\
 
\

\

\
 \


Harness or connector between O/D direct clutch speed sensor and ECM.
\
 \

O/D direct clutch speed sensor.AT±98
\
 \

ECM
\
 \

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*1: ªOº mark means ªO/D OFFº light blinks once every 2 seconds.\
ªXº mark means ªO/D OFFº light never
blinks.
*2: ªOº mark means the ECM memorizes the malfunction code if the ECM detects the diag. trouble \
code
detection condition.
*3: This indicates items for which ª2 trip detection logicº is use\
d. With this logic, when a logic malfunction
is first detected, the malfunction is temporarily stored in the ECM memory. If the same case is detected
again during the second drive test, this second detection causes the O/F\
OFF Light to blink.
The 2 trip repeats the same mode twice. (However, the IG switch must be turned OFF between the 1st trip
and 2nd trip.)
HINT:

If the malfunction returns to normal while a malfunction warning is being \
output, the O/D OFF indicator
light stops blinking and goes off.
However, the malfunction code is retained in memory until it is cleared from me\
mory.

If the diagnosis system outputs a malfunction code even though the O/D OFF indicator was not
blinking, there is intermittent trouble. Check all the connections in the circuit\
s corresponding to that
code.

If the vehicle speed sensors No.1 and No.2 happen to fail simultaneously\
, the ECM will neither alert
the driver by blinking the O/D OFF indicator nor record any diagnostic t\
rouble code. It will, however,
decide that the vehicle can be driven only in 1st and none of the other gears, shifting \
upwards will then
be prohibited.

Codes 46, 62, 63 and 64 are limited to short or open circuits in the electric\
al system comprised of the
solenoids, wire harnesses and connectors. The ECM is unable to detect mechanical t\
rouble (sticking,
for example) in the solenoid valves.
AT±62
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MATRIX CHART OF PROBLEM SYMPTOMS
AT0LS±08
If a normal code is displayed during the diagnostic trouble code check but\
the trouble still occurs, check
the circuits for each symptom in the order given in the charts on the fo\
llowing pages and proceed to the
page given for troubleshooting.
The Matrix Chart is divided into 3 chapters.
Chapter 1: Electronic Circuit Matrix Chart
Chapter 2: On±vehicle Repair Matrix Chart
Chapter 3: Off±vehicle Repair Matrix Chart
In troubleshooting, check Chapter 1 first. If instructions are given in Ch\
apter 1 to proceed to Chapter 2 or
3, proceed to it.
1. If the instruction ªProceed to next circuit inspection shown on matrix chartº is given in the flow chart for each circuit, proceed to the circuit with the next highest number in the\
table to continue
the check.
2. If the trouble still occurs even though there are no abnormalities in an\
y of the other circuits, then check or replace the ECM.
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Chapter 1. Electronic Circuit
AT ±7
8
AT ±
8
2
AT±86
AT±90
AT±94
AT±98
AT±102
AT±66±
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LOCATION OF CONNECTORS
AT0LA±02
Location of Connectors in Engine Compartment
AT±72±
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