1991 LEXUS SC400 wiring

WIRING DIAGRAM
AT±66
IN±33
Throttle Position Sensor Circuit
CIRCUIT DESCRIPTION
The throttle position sensor detects the throttle valve opening angle and s\
ends signals to ECM.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
AT±102±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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AT±66
IN±33
WIRING DIAGRAM
Kick±down Switch Circuit
CIRCUIT DESCRIPTION
The kick±down switch is turned on when the accelerator ped-
al is depressed beyond the full throttle opening and sends sig-
nals to the ECM.
When the kick±down switch is turned on, the ECM controls
gear shifting according to the programmed shift diagrams.
If a short circuit develops in the kick±down switch, the ECM
disregards the kick±down signals and controls shifting at the
normal shift points.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
AT±104±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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The park/neutral position switch detects the shift lever
position and sends signals to ECM.The ECM receives
signals (R, PNP, 2 and L) from the park/neutral position
switch. When the signal is not sent to the ECM from the
park/neutral position switch, the ECM judges that the
shift lever is in the D position.
AT±66
IN±33
WIRING DIAGRAM
Park/neutral Position Switch Circuit
CIRCUIT DESCRIPTION
DIAGNOSTIC CHARTDIAGNOSTIC CHART
AT±106±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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AT±66BE
IN±33
WIRING DIAGRAM
Stop Light Switch Circuit
CIRCUIT DESCRIPTION
The purpose of this circuit is to prevent the engine from stalling, while d\
riving in lockup condition, when
brakes are suddenly applied.When the brake pedal is operated, this switch sends a signal to ECM. Then
the ECM cancels operation of the lockup clutch while braking is in progress\
.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
AT±108±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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AT±66
IN±33
WIRING DIAGRAM
Pattern Select Switch Circuit
CIRCUIT DESCRIPTION
The ECM memory contains the shift programs for the NORMAL and POWER pattern\
s, 2 position and L
position and the lock±up patterns. Following the programs corresponding to the\
signals from the pattern
select switch, the park/neutral position switch and other various sensor\
s the ECM switches the solenoid
valves ON and OFF, thereby controlling the transmission gear change and the lock±up cl\
utch operation.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
AT±110±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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WIRING DIAGRAM
O/D Main Switch and O/D OFF Indicator Light Circuit
CIRCUIT DESCRIPTION
The O/D main switch contacts go off when the switch is pushed in and comes on when it is pushed out.
In O/D main switch OFF position, the O/D OFF indicator lights up, and the \
ECM prohibits shifting to over-
drive. The ECM also causes the O/D OFF indicator light to blink when a malfunc\
tion is detected. In this
case, connecting the terminals in the DLC2 or DLC1 can display the malfu\
nction code.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
See next page.
AT±112
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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AT±66
IN±33
WIRING DIAGRAM
O/D Cancel Signal Circuit
CIRCUIT DESCRIPTION
While driving with cruise control activated, in order to minimize gear shifti\
ng and provide smooth cruising
when driving uphill, overdrive may be prohibited temporarily in some conditions.The cruise control ECU
sends O/D cut signals to the ECM as necessary and the ECM cancels overdrive s\
hifting until these signals
are discontinued.(For details, see the cruise control system, on BE sectio\
n).
DIAGNOSTIC CHARTDIAGNOSTIC CHART
AT±116±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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AT±66
IN±33
WIRING DIAGRAM
TE1 Terminal Circuit
CIRCUIT DESCRIPTION
ECM displays diagnostic trouble codes using the O/D OFF indicator light \
when terminals TE and E of the
DLC2 or DLC1 are connected.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
AT±118±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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