P0748

A761E AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: P0748: Pressure Control Solenoid "A" Electrical (Shift Solenoid Valve SL1)

DTC 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 Fail-Safe Chart.










1. Reference: Inspect using an oscilloscope.
Check the waveform of the ECM connector.
OK:
Refer to illustration.






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 Fail-Safe Chart.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





COMPONENT OPERATING RANGE





WIRING DIAGRAM





INSPECTION PROCEDURE
HINT: The shift solenoid valve SL1 turns ON/OFF normally when the shift lever is on D:





PROCEDURE

1. INSPECT TRANSMISSION WIRE (SHIFT SOLENOID VALVE SL1)




(a) Disconnect the E1 wire connector.
(b) Measure the resistance of the transmission wire.
Standard resistance:






NG -- INSPECT SHIFT SOLENOID VALVE SL1
OK -- Continue to next step.
2. CHECK WIRE HARNESS (TRANSMISSION WIRE - ECM)




(a) Disconnect the E3 ECM connector.
(b) Measure the resistance of the wire harness side connector.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- REPLACE ECM
3. INSPECT SHIFT SOLENOID VALVE SL1
(a) Remove the shift solenoid valve SL1.




(b) Measure the resistance of the solenoid valve.
Standard resistance:





(c) Connect the battery's positive (+) lead with a 21 W bulb to terminal 2 and the negative (-) lead to terminal 1 of the solenoid valve connector. Then check that the valve moves and makes an operating noise.
OK:
Valve moves and makes operating noise.
NG -- REPLACE SHIFT SOLENOID VALVE SL1
OK -- REPAIR OR REPLACE TRANSMISSION WIRE