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

WARNING: This page is about a different car, the 2006 Lexus IS 350. However, it is still accessible from the selected car via links, so may be relevant.

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 (See DIAGNOSIS SYSTEM ).

DTC TROUBLE DETECTION CONDITION

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) Output signal duty equals to 100%. (NOTE: SL1 output signal duty is less than 100% under normal condition.)	Open or short in shift solenoid valve SL1 circuit Shift solenoid valve SL1 ECM

Reference (Using an oscilloscope):

Check the waveform between the terminals SL1+ and SL1- of the ECM connector

Fig 1: Identifying Oscilloscope Voltage Waveform Signal

Standard:

Refer to the illustration.

TERMINALS SPECIFICATION

Terminal	SL1+ - SL1-
Tool setting	5 V/DIV., 1 ms./DIV.
Vehicle condition	5th or 6th gear