2003 LEXUS LS430 Ecm

NG: REPLACE SHIFT SOLENOID VALVE SLT
OK: GO TO NEXT STEP
4.CLEAR THE DTC AND RUNNING TEST
a. Clear the DTC, and check DTC again after conducting the "MONITOR DRIVE PATTERN FOR
ECT TEST" (see MONITOR DRIVE PATTERN
).
OK:
No DTC code
NG: REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSY (See step 6 on
REPLACEMENT
)
OK: END
DTC P0973, P0974: SHIFT SOLENOID "A" CONTROL CIRCUIT LOW/HIGH (SHIFT SOLENOID
VALVE S1)
CIRCUIT DESCRIPTION
ItemTest DetailsDiagnostic Note
LINE PRESS UP(1)
[Test Details]
Operate shift solenoid SLT and
raise line pressure
[Vehicle Condition]
Vehicle stopped
IDL: ON

HINT:
OFF: Line pressure up (when
Active Test "LINE PRESS UP" is
performed, ECM commands SLT
solenoid to turn OFF)
ON: No action (normal operation)
-
HINT:
The pressure values in ACTIVE TEST and HYDRAULIC TEST are different from each other.
Normally, the line pressure detected in the ACTIVE TEST is approximately half of the value
detected in the HYDRAULIC TEST's stall test.
(1)"LINE PRESS UP" in the ACTIVE TEST is performed to check the line pressure change by
connecting SST to the automatic transmission, which is used in the HYDRAULIC TEST
(see )

Shifting from 1st to 6th is performed in combination with "ON" and "OFF" operation of the shift solenoid
valves SL1, SL2, S1, S2, S3, S4 and SR which is controlled by the ECM. If an open or short circuit occurs in
either of the shift solenoid valves, the ECM controls the remaining normal shift solenoid valve to allow the
vehicle to be operated smoothly. (In case of an open or short circuit, the ECM stops sending current to the
circuit.) Fail safe function (see FAIL
-SAFE CHART ).
Fig. 133: DTC Reference Chart

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
MONITOR DESCRIPTION
These DTCs indicate an open or short in the shift solenoid valve S1 circuit. When there is an open or short
circuit in any shift solenoid valve circuit, the ECM detects the problem and illuminates the MIL and stores the
DTC. When the shift solenoid valve S1 is on, if resistance is 8 ohms or less, the ECM determines there is a
short in the shift solenoid valve S1 circuit.
When the shift solenoid valve S1 is off, if resistance is 100 kohms or more, the ECM determines there is an
open in the shift solenoid valve S1 circuit (see FAIL
-SAFE CHART ).
MONITOR STRATEGY
MONITOR STRATEGY TABLE
TYPICAL ENABLING CONDITIONS
P0973: Range check (Low resistance)
TYPICAL ENABLING CONDITIONS TABLE - P0973
Related DTCsP0973: Shift solenoid valve S1 /Range check (Low
resistance) P0974: Shift solenoid valve S1 /Range
check (High resistance)
Required sensors/ComponentsShift solenoid valve S1
Frequency of operationContinuous
Duration0.064 sec. or more
MIL operationImmediate
Sequence of operationNone
The monitor will run whenever this DTC is not
present.See LIST OF DISABLE A MONITOR

1.INSPECT TRANSMISSION WIRE (S1)
a. Disconnect the transmission wire connector from the transmission.
b. Measure the resistance according to the value(s) in the table below.
Fig. 135: Identifying Transmission Wire Terminals

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
Standard:
TRANSMISSION WIRE (S1) - RESISTANCE TABLE
NG: Go to step 3
OK: Go to next step
2.CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE - ECM)
a. Connect the transmission connector to the transmission.
b. Disconnect the connector from the ECM.
Tester ConnectionSpecified Condition 20°C (68°F)
8 - Body ground11 to 15ohms

c. Measure the resistance according to the value(s) in the table below.
Fig. 136: Disconnecting Connector From ECM

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
Standard:
TRANSMISSION WIRE - ECM - RESISTANCE TABLE
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (See ELECTRONIC CIRCUIT
INSPECTION PROCEDURE )
OK: REPLACE ECM (See REPLACEMENT
)
3.INSPECT SHIFT SOLENOID VALVE (S1)
a. Remove the shift solenoid valve S1.
b. Measure the resistance according to the value(s) in the table below.
Standard:
Tester ConnectionSpecified Condition 20°C (68°F)
E6 - 19 (S1) - Body ground11 to 15ohms

CIRCUIT DESCRIPTION
Shifting from 1st to 6th is performed in combination with "ON" and "OFF" operation of the shift solenoid
valves SL1, SL2, S1, S2, S3, S4 and SR which is controlled by the ECM. If an open or short circuit occurs in
either of the shift solenoid valves, the ECM controls the remaining normal shift solenoid valve to allow the
vehicle to be operated smoothly. (In case of an open or short circuit, the ECM stops sending current to the
circuit.) Fail safe function (see FAIL
-SAFE CHART ).
Fig. 138: DTC Reference Chart

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
MONITOR DESCRIPTION
These DTCs indicate an open or short in the shift solenoid valve S2 circuit. When there is an open or short
circuit in any shift solenoid valve circuit, the ECM detects the problem and illuminates the MIL and stores the
DTC. When the shift solenoid valve S2 is on, if resistance is 8ohms or less, the ECM determines there is a short
in the shift solenoid valve S2 circuit.
When the shift solenoid valve S2 is off, if resistance is 100 kohms or more, the ECM determines there is an
open in the shift solenoid valve S2 circuit (see FAIL
-SAFE CHART ).
MONITOR STRATEGY
MONITOR STRATEGY TABLE
TYPICAL ENABLING CONDITIONS
P0976: Range check (Low resistance)
TYPICAL ENABLING CONDITIONS TABLE - P0976
Related DTCsP0976: Shift solenoid valve S2/Range check (Low
resistance) P0977: Shift solenoid valve S2/Range
check (High resistance)
Required sensors/ComponentsShift solenoid valve S2
Frequency of operationContinuous
Duration0.064 sec. or more
MIL operationImmediate
Sequence of operationNone

INSPECTION PROCEDURE
1.INSPECT TRANSMISSION WIRE (S2)
a. Disconnect the transmission wire connector from the transmission.
b. Measure the resistance according to the value(s) in the table below.
Fig. 140: Identifying Transmission Wire Connector Terminals

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
Standard:
TRANSMISSION WIRE (S2) - RESISTANCE TABLE
NG: Go to step 3
OK: Go to next step
2.CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE - ECM)
a. Connect the transmission connector to the transmission.
Tester ConnectionSpecified Condition 20°C (68°F)
15 - Body ground11 to 15ohms

b. Disconnect the connector from the ECM.
c. Measure the resistance according to the value(s) in the table below.
Fig. 141: Disconnecting Connector From ECM

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
Standard:
TRANSMISSION WIRE - ECM - RESISTANCE TABLE
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (See ELECTRONIC CIRCUIT
INSPECTION PROCEDURE )
OK: Go to next step
OK: REPLACE ECM (See REPLACEMENT
)
3.INSPECT SHIFT SOLENOID VALVE (S2)
a. Remove the shift solenoid valve S2.
Tester ConnectionSpecified Condition 20°C (68°F)
E6 - 18 (S2) - Body ground11 to 15ohms

DTC P0979, P0980: SHIFT SOLENOID "C" CONTROL CIRCUIT LOW/HIGH (SHIFT SOLENOID
VALVE S3)
CIRCUIT DESCRIPTION
Shifting from 1st to 6th is performed in combination with "ON" and "OFF" operation of the shift solenoid
valves SL1, SL2, S1, S2, S3, S4 and SR which is controlled by the ECM. If an open or short circuit occurs in
either of the shift solenoid valves, the ECM controls the remaining normal shift solenoid valve to allow the
vehicle to be operated smoothly. (In case of an open or short circuit, the ECM stops sending current to the
circuit.) Fail safe function (see FAIL
-SAFE CHART ).
Fig. 143: DTC Reference Chart

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
MONITOR DESCRIPTION
These DTCs indicate an open or short in the shift solenoid valve S3 circuit. When there is an open or short
circuit in any shift solenoid valve circuit, the ECM detects the problem and illuminates the MIL and stores the
DTC. When the shift solenoid valve S3 is on, if resistance is 8ohms or less, the ECM determines there is a short
in the shift solenoid valve S3 circuit.
When the shift solenoid valve S3 is off, if resistance is 100 kohms or more, the ECM determines there is an
open in the shift solenoid valve S3 circuit (see FAIL
-SAFE CHART ).
MONITOR STRATEGY
MONITOR STRATEGY TABLE
TYPICAL ENABLING CONDITIONS
Related DTCsP0979: Shift solenoid valve S3/Range check (Low
resistance) P0980: Shift solenoid valve S3/Range
check (High resistance)
Required sensors/ComponentsShift solenoid valve S3
Frequency of operationContinuous
Duration0.064 sec. or more
MIL operationImmediate
Sequence of operationNone