P0748

A760H AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM (for 4GR-FSE): P0748: Pressure Control Solenoid "A" Electrical (Shift Solenoid Valve SL1)
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 Fail-Safe Chart.

Reference (Using an oscilloscope):

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

Standard:

Refer to the illustration.

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 Fail-Safe Chart.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

WIRING DIAGRAM

INSPECTION PROCEDURE

NOTICE:
Perform the universal trip to clear permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

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

PROCEDURE

1. INSPECT TRANSMISSION WIRE (SL1)

(a) Disconnect the transmission wire connector from the transmission.

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

Standard resistance:

NG -- INSPECT SHIFT SOLENOID VALVE SL1
OK -- Continue 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.

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

Standard resistance:

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

Standard resistance (Check for short):

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM

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:

(c) 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