LEXUS SC400 1991 Service Repair Manual

DIAGNOSTIC TROUBLE CODE CHART
AT0LR±04
If a malfunction code is displayed during the diagnostic trouble code chec\
k, check the circuit listed for that
code in the table below and proceed to the page given.
AT±60±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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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
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 \

ECM
\
 \

\
 \
   
\
 \

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

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

ECM 

 

 
\
 
\

\

 


 


 


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 \

\
 \


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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STANDARD VALUE OF ECM TERMINAL
AT0L9±04
(*A=E9, B=E10)
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±63
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±Memo± AT±64
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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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AT±106AT±104 AT±108
AT±110
AT±112
AT±116
AT±68
AT±70
IN±26
EG±580
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±67
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Chapter 2. On±Vehicle Repair
( : '94 A340E and A341E AUTOMATIC TRANSMISSION Repair Manual for LEXUS SC400)
AT±48
AT±48
V04379
AT±68±
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AT±70
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±69
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