P0748

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) 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

Standard:

Refer to the illustration.

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

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

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)

1. Disconnect the transmission wire connector from the transmission.

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

   Standard resistance:

   Tester Connection	Specified Condition 20°C (68°F)
   11 (SL1+) - 3 (SL1-)	5.0 to 5.6 Ω

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

   Standard 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)

1. Connect the transmission connector to the transmission.

2. Disconnect the connector from the ECM.

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

   Standard resistance:

   Tester Connection	Specified Condition 20°C (68°F)
   E4-25 (SL1+) - E4-24 (SL1-)	5.0 to 5.6 Ω

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

   Standard resistance (Check for short):

   Tester Connection	Specified Condition
   E4-25 (SL1+) - Body ground	10 kΩ or higher
   E4-24 (SL1-) - Body ground	↑

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK
REPLACE ECM

3. INSPECT SHIFT SOLENOID VALVE SL1

1. Remove the shift solenoid valve SL1.

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

   Standard resistance:

   Tester Connection	Specified Condition 20°C (68°F)
   1 - 2	5.0 to 5.6 Ω

3. 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