LEXUS SC400 1991 Service Repair Manual

OKNG
OKNG
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal P of ECM connector and body ground.
C
OK
Hint
P1. Connect the check harness A to the ECM (See EGsection).
2. Turn ignition switch ON.
Measure voltage between terminal P of ECM connector
and body ground when the pattern select switch is set
to the PWR (POWER) position and NORM (NORMAL)
position.
The ECM uses the normal pattern signal if the power
signal is not input.
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check pattern select switch.
C
OK
PDisconnect pattern select switch connector. (See BO
section).
Measure resistance between terminals 1 and 2 of pat-
tern select switch connector when the select switch is
set to PWR and NORM positions.
Replace pattern select switch.
3Check harness and connector between ECM and pattern select switch, patte\
rn select switch
and battery (See page IN±33).
Repair or replace harness or connector.
Check and replace ECM.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±111
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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
±
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O/D OFF indicator light does not light up.
AT±66
BE IN±33
IN±33
O/D OFF indicator light blinks
Perform diagnostic trouble code check (See page AT±38).
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±113
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OKNG
OKNG
OKNG
INSPECTION PROCEDURE
1Check operation of O/D Main Switch
C
OK
Hint
C
OK
1. Turn ignition switch ON.
2. Check ªO/D OFFº light when O/D main switch ispushed in to ON.
ªO/D OFFº light goes off.
3. Check ªO/D OFFº light when O/D main switch is pushed again, to OFF.
ªO/D OFFº light lights up.
If the ªO/D OFFº lights blinks when the O/D main switch
is pushed in to ON, a malfunction is occurring in the sys-
tem.
Check the diagnostic trouble code.
Go to step
.
2Check voltage between terminal OD2 of ECM connector and body ground.
C
OK
P1. Connect the check harness A to the ECM (See EG
section).
2. Turn ignition switch ON.
Check voltage between terminal OD2 of ECM and body
ground
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
3Check harness and connector between O/D off indicator light and ECM (Se\
e page IN±33).
Repair or replace harness or connector.
Check and replace ECM.
AT±114±
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OKNG
4Check O/D Main Switch.
C
OK
1. Disconnect O/D main switch connector. (See BOsection).
2. Measure resistance between terminals 2 and 4 of O/D main switch connector.
Replace O/D Main Switch.
Check and replace combination meter. (See com-
bination meter troubleshooting on BE section).
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±115
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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±
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NGOK
NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal OD1of ECM connector and body ground.
C
OK
P1. Connect the check harness A to the ECM (See EGsection).
2. Turn ignition switch ON.
Measure voltage between terminal OD1 of ECM con-
nector and body ground.
Voltage: 4 ± 6 V
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check voltage between terminal OD of cruise control ECU harness side con\
nector and body
ground.
C
OK
P1. Disconnect cruise control ECU connector.
2. Turn ignition switch ON.
Measure voltage between terminal OD of cruise control
ECU harness side connector and body ground.
Voltage: 4 ± 6± V
Check and replace cruise control ECU.
3Check harness or connector between cruise control ECU and ECM (See page\
IN±33).
Repair or replace harness or connector.
Check and replace ECM.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±117
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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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OKNG
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal TE1 and E1 of DLC2 or DLC1.
C
OK
Measure voltage between terminals TE1 and E1 of
DLC2 or DLC1.
Voltage: 4 ± 6 V
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check harness and connector between ECM and DLC2, DLC1 and body ground (See page
IN±33).
Repair or replace harness or connector.
Check and replace ECM.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±119
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IN±33
WIRING DIAGRAM
TT Terminal Circuit
CIRCUIT DESCRIPTION
Checks of ECM input and output signals related to the throttle position sensor\
brakes, shift position and
other circuits can be performed by measuring the voltages at terminal T
T of the DLC1.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
AT±120±
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