Dtc P0748 Pressure Control Solenoid A Electrical (Shift Solenoid Valve Sl1)

Transmission. Lexus Gs430, Gs300. Uzs190 Grs190
A761E Automatic Transmission. Lexus Gs430, Gs300. Uzs190 Grs190

DESCRIPTION

MONITOR DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT TRANSMISSION WIRE (SL1)

CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE - ECM)

INSPECT SHIFT SOLENOID VALVE SL1

DTC P0748 Pressure Control Solenoid "A" Electrical (Shift Solenoid Valve SL1)


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 (Click here).

DTC No.
DTC Detection Condition
Trouble Area
P0748
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)
  1. Output signal duty equals to 100%.
    (NOTE: SL1 output signal duty is less than 100% under normal condition.)
  1. Open or short in shift solenoid valve SL1 circuit
  2. Shift solenoid valve SL1
  3. ECM

MONITOR DESCRIPTION

This DTC indicates an open or short in the shift solenoid valve SL1 circuit. The ECM commands gearshift 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 and illuminates the MIL and stores the DTC. And 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 current to the circuit.)
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 there is a malfunction (Click here).

WIRING DIAGRAM


Lexus Gs430, Gs300. Uzs190 Grs190.A761E Automatic Transmission.Electronic Controlled Automatic Transmission System.
Dtc
  P0748  Pressure Control Solenoid A Electrical (Shift Solenoid Valve Sl1)


INSPECTION PROCEDURE

HINT:
  1. The shift solenoid valve SL1 is turned on/off normally when the shift lever is in the D position:

    ECM command gearshift
    1st
    2nd
    3rd
    4th
    5th
    6th
    Shift solenoid valve SL1
    OFF
    OFF
    OFF
    OFF
    ON
    ON
1.INSPECT TRANSMISSION WIRE (SL1)


    Lexus Gs430, Gs300. Uzs190 Grs190.A761E Automatic Transmission.Electronic Controlled Automatic Transmission System.
Dtc
  P0748  Pressure Control Solenoid A Electrical (Shift Solenoid Valve Sl1)
  1. Disconnect the transmission wire connector from the transmission.

  1. Measure the resistance according to the value(s) in the table below.

    Resistance:
    Tester Connection
    Specified Condition
    20°C (68°F)
    11 (SL1+) - 3 (SL1-)
    5.0 to 5.6 Ω
  1. Measure the resistance according to the value(s) in the table below.

    Resistance (Check for short):
    Tester Connection
    Specified Condition
    11 (SL1+) - Body ground
    10 kΩ or higher
    3 (SL1-) - Body ground



NG
Go to step 3
OK


2.CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE - ECM)


    Lexus Gs430, Gs300. Uzs190 Grs190.A761E Automatic Transmission.Electronic Controlled Automatic Transmission System.
Dtc
  P0748  Pressure Control Solenoid A Electrical (Shift Solenoid Valve Sl1)
  1. Connect the transmission connector to the transmission.

  1. Disconnect the connector from the ECM.

  1. Measure the resistance according to the value(s) in the table below.

    Resistance:
    Tester Connection
    Specified Condition
    20°C (68°F)
    E7 - 25 (SL1+) - E7 - 24 (SL1-)
    5.0 to 5.6 Ω
  1. Measure the resistance according to the value(s) in the table below.

    Resistance (Check for short):
    Tester Connection
    Specified Condition
    E7 - 25 (SL1+) - Body ground
    10 kΩ or higher
    E7 - 24 (SL1-) - Body ground



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE ECM

3.INSPECT SHIFT SOLENOID VALVE SL1
Lexus Gs430, Gs300. Uzs190 Grs190.A761E Automatic Transmission.Electronic Controlled Automatic Transmission System.
Dtc
  P0748  Pressure Control Solenoid A Electrical (Shift Solenoid Valve Sl1)
  1. Remove the shift solenoid valve SL1.

  1. Measure the resistance according to the value(s) in the table below.

    Resistance:
    Tester Connection
    Specified Condition
    20°C (68°F)
    1 - 2
    5.0 to 5.6 Ω
  1. Connect the positive (+) lead with a 21 W bulb to terminal 2 and the negative (-) lead to terminal 1 of the solenoid valve connector, then check the movement of the valve.

    OK:
    The solenoid makes an operating sound.


NG
REPLACE SHIFT SOLENOID VALVE SL1
OK

REPAIR OR REPLACE TRANSMISSION WIRE