4/23/25, 2:11 PM Inspection Procedure - Toyota Service Information
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AB60E AUTOMATIC TRANSMISSION / TRANSAXLE AUTOMATIC TRANSMISSION SYSTEM P0748 Pressure Control
Solenoid "A" Electrical (Shift Solenoid Valve SL1)
DESCRIPTION
Shifting from 1st to 5th is performed in combination with the ON and OFF operation of the shift solenoid valves SL1, SL2, S1, S2,
S3, S4 and SR, which are controlled by the ECM. If an open or short circuit occurs in the shift solenoid valves, the ECM controls
the remaining normal shift solenoid valves to allow the vehicle to be operated safely (See page Drivetrain>AB60E AUTOMATIC
TRANSMISSION / TRANSAXLE>AUTOMATIC TRANSMISSION SYSTEM>FAIL-SAFE CHART).
DTC Code DTC Detection Condition Trouble Area
The ECM checks for an open or short in the shift
solenoid valve SL1 circuit while driving and shifting
between 4th and 5th gear (1 trip detection logic) · Open or short in shift solenoid valve
Output signal duty equals to 100% SL1 circuit
P0748 · Shift solenoid valve SL1
HINT:
SL1 output signal duty is less than 100% under · ECM
normal condition
Inspect using an oscilloscope:
Check the waveform of the ECM connector.
Standard:
Refer to the illustration.
Item Content
D56-14 (SL1+) - D56-15
Terminal No. (Symbol)
(SL1-)
Tool setting 5 V/DIV., 1 msec./DIV.
Condition 5th or 6th gear
MONITOR DESCRIPTION
This DTC indicates an open or short in the shift solenoid valve SL1 circuit. The ECM commands gear shifts by turning the shift
solenoid valves ON/OFF. When there is an open or short circuit in any shift solenoid valve circuit, the ECM detects the problem,
illuminates the MIL and stores the DTC. Also, the ECM performs the fail-safe function and turns the other normal shift solenoid
valves ON/OFF. In case of an open or short circuit, the ECM stops sending the current to the open or short circuited solenoid.
While driving and shifting between 4th and 5th gears, if the ECM detects an open or short in the shift solenoid valve SL1 circuit,
the ECM determines that there is a malfunction (See page Drivetrain>AB60E AUTOMATIC TRANSMISSION /
TRANSAXLE>AUTOMATIC TRANSMISSION SYSTEM>FAIL-SAFE CHART).
WIRING DIAGRAM
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4/23/25, 2:11 PM Inspection Procedure - Toyota Service Information
CAUTION / NOTICE / HINT
HINT:
The shift solenoid valve SL1 turns ON/OFF normally when the shift lever is in D:
ECM gear shift
1st 2nd 3rd 4th 5th 6th
command
Shift solenoid
OFF OFF OFF OFF ON ON
valve SL1
PROCEDURE
1.INSPECT NO. 1 TRANSMISSION WIRE (SHIFT SOLENOID VALVE SL1)
a.
Disconnect the D41 No. 1 transmission wire connector.
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4/23/25, 2:11 PM Inspection Procedure - Toyota Service Information
b. Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Specified
Condition
Connection Condition
11 (SL1+) - 3
20°C (68°F) 5.0 to 5.6 Ω
(SL1-)
11 (SL1+) - Body
Always 10 kΩ or higher
ground
3 (SL1-) - Body
Always 10 kΩ or higher
ground
OK
2.CHECK HARNESS AND CONNECTOR (NO. 1 TRANSMISSION WIRE - ECM)
NG
3.INSPECT SHIFT SOLENOID VALVE SL1
2.CHECK HARNESS AND CONNECTOR (NO. 1 TRANSMISSION WIRE - ECM)
a. Disconnect the D56 ECM connector.
b. Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Specified
Condition
Connection Condition
D56-14 (SL1+) -
20°C (68°F) 5.0 to 5.6 Ω
D56-15 (SL1-)
D56-14 (SL1+) -
Always 10 kΩ or higher
Body ground
D56-15 (SL1-) -
Always 10 kΩ or higher
Body ground
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4/23/25, 2:11 PM Inspection Procedure - Toyota Service Information
OK
REPLACE ECM
(See pageEngine / Hybrid System>3UR-FE ENGINE CONTROL>ECM>REMOVAL)
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
3.INSPECT SHIFT SOLENOID VALVE SL1
a. Remove the shift solenoid valve SL1.
b. Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Specified
Condition
Connection Condition
1-2 20°C (68°F) 5.0 to 5.6 Ω
c. Connect the battery positive (+) lead with a 21 W bulb to terminal 1 and the negative (-) lead to terminal 2 of the
solenoid valve connector. Then check that the valve moves and makes an operating noise.
OK:
Valve moves and makes an operating noise.
OK
REPAIR OR REPLACE NO. 1 TRANSMISSION WIRE
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4/23/25, 2:11 PM Inspection Procedure - Toyota Service Information
(See pageDrivetrain>AB60E AUTOMATIC TRANSMISSION / TRANSAXLE>TRANSMISSION WIRE>REMOVAL)
NG
REPLACE SHIFT SOLENOID VALVE SL1
(See pageDrivetrain>AB60E AUTOMATIC TRANSMISSION / TRANSAXLE>VALVE BODY
ASSEMBLY>DISASSEMBLY)
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