1991 LEXUS SC400 sensor

DTC61No.2 Vehicle Speed Sensor Circuit
CIRCUIT DESCRIPTION
The No.2 speed sensor detects the rotation speed of the transmission output shaft and sends signals to the
ECM. The ECM determines the vehicle speed based on the these signals. An AC voltage i\
s generated in the
No.2 vehicle speed sensor coil as the rotor mounted on the output shaft rota\
tes, and this voltage is sent to the
ECM.
The gear shift point and lock±up timing are controlled by the ECM based \
on the signals from this vehicle speed
sensor and the throttle position sensor signal.
If the No.2 vehicle speed sensor malfunctions, the ECM uses input signals \
from the No.1 vehicle speed sensor
as a back±up signal.
DTC No.DTC Detecting ConditionTrouble Area
61
All conditions below are detected 500 times or more
continuously.
2 trip detection logic*
(a) No No.2 vehicle speed sensor signal in 4 No.1 ve-
hicle speed sensor signal pulses.
(b) Vehicle speed: 5.6 MPH (9 km/h) or more for
at least 4 secs.
(c) Park/neutral position switch:
OFF (Other than P or N position)

No. 2 vehicle speed sensor

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

ECM
*: See page AT±62
Reference

Waveform between terminals SP2+ and SP2± when vehicle speed is approx.\
37 MPH (60km/h).
AT±86
±
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NGOK
OKNG
INSPECTION PROCEDURE
1Check resistance between terminals SP2+ and SP± of ECM connector.
C
OK
PConnect the check A to the ECM. (See EG section).
Check resistance between terminals SP
+ and SP2± of
ECM connector.
Resistance: 560 ± 680

Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check No.2 vehicle speed sensor.
C
OK
Hint
P
OK
C
Remove No.2 vehicle speed sensor from transmission.
(See page AT±17).
Measure resistance between terminals 1 and 2 of speed
sensor.
Resistance: 560 ± 680

Reference
Check the vehicle speed sensor's function
Check voltage between terminals 1 and 2 of the vehicle
speed sensor when a magnet is put close to the front
end of the vehicle speed sensor then taken away quick-
ly.
Voltage is generated intermittently.
The voltage generated is extremely low.
Replace No.2 vehicle speed sensor.
Check and repair harness and connector between
ECM and No.2 vehicle speed sensor (See page
IN±33).
AT±88±
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This sensor detects the rotation speed of the O/D input shaft from the
rotation of the O/D direct clutch drum.
Its construction is the same as that of the No. 2 vehicle speed sensor
(See page AT±86).
By comparing the O/D direct clutch speed signal and the No. 2 vehicle
speed sensor signal, ECM detects the shift timing of the gears and ap-
propriately controls the engine torque and hydraulic pressure in re-
sponse to various conditions, thus performing smooth gear shift.
DTC67O/D Direct Clutch Speed Sensor Circuit
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
67
All conditions below are detected for 4 secs. or more
2 trip detection logic*
(a) Gear position: 1st, 2nd and 3rd
(b) T/M input shaft rpm: 100 rmp or more
(c) T/M output shaft rpm: less than 300 rpm
(d) PNP: OFF (other than P or N position)

O/D direct clutch speed sensor.

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

ECM
*: See page AT±62.
Reference

Wave form between terminals NCO
+ and NCO± during engine idling.
AT±98
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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NGNG
OKNG
INSPECTION PROCEDURE
1Check resistance between terminals NCO+ and NCO± of ECM connector.
C
OK
PConnect the check harness A to the ECM (See EG sec-
tion).
Check resistance between terminals NCO
+ and NCO±
of ECM connector.
Resistance: 560 ± 680

Proceed to next circuit inspection shown on matrix chart
(See page AT±66). However, when diag. trouble code 67
is displayed, check and replace ECM.
2Check O/D direct clutch speed sensor.
C
OK
Hint
P
OK
C
Remove O/D direct clutch speed sensor from transmis-
sion (See page AT±17).
Measure resistance between terminals 1 and 2 of O/D
direct clutch speed sensor.
Resistance: 560 ± 680

Reference
Check the speed sensor function
Check voltage between terminals 1 and 2 of the speed
sensor when a magnet is put close to the front end of the
speed sensor then taken away quickly.
Voltage is generated intermittently.
The voltage generated is extremely low.
Replace O/D direct clutch speed sensor.
Check and repair harness and connector between
ECM and O/D direct clutch speed sensor (See
page IN±33).
AT±100±
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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±
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OKNG
OKNG
OKNG
INSPECTION PROCEDURE
1Main throttle position signal check.
C
OK
Hint
PTurn ignition switch ON (Do not start the engine).
Check voltage at the terminal T
T of the DLC2 while grad-
ually depressing the accelerator pedal from the fully
closed position to the fully opened position.
Voltage changes from 0 V to 8 V by stages.
Do not depress the brake pedal during this test. The
voltage will stay at 0 V if depressed.
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check throttle position sensor.
See engine troubleshooting section in EG section.
Replace throttle position sensor.
3Check harness and connector between ECM and throttle position sensor (S\
ee page IN±33).
Repair or replace harness or connector.
Check and replace ECM.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±103
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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±
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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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