Home › Drivetrain › Automatic Transmission/Transaxle › AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM
Last Modified: 11-27-2007 1.6 C
Service Category: Drivetrain Section: Automatic Transmission/Transaxle
Model Year: 2008 Model: LX570 Doc ID: RM000000W8F04LX
Title: AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 LX570)

DTC

P0748

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

DESCRIPTION

Shifting from 1st to 6th is performed in combination with the ON and OFF operation of 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 AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: FAIL-SAFE CHART (2008 LX570) .

DTC Code

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).

The output signal duty equals 100%.

HINT:

The SL1 output signal duty is less than 100% under normal conditions.
  • Open or short in shift solenoid valve SL1 circuit
  • Shift solenoid valve SL1
  • ECM

Reference: Inspect using an oscilloscope.

Check the waveform of the ECM connector.

Standard:

Terminal No. (Symbol)

Tool Setting

Condition

Specified Condition

C53-14 (SL1+) - C53-15 (SL1-)

5 V/DIV., 1 msec./DIV.

Engine idling

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 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 AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: FAIL-SAFE CHART (2008 LX570) .

MONITOR STRATEGY

Related DTCs

P0748: Shift solenoid valve SL1/Range check

Required sensors/Components

Shift solenoid valve SL1

Frequency of operation

Continuous

Duration

1 sec.

MIL operation

Immediately

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

All

The monitor will run whenever the following DTCs are not stored

None

Engine switch

On (IG)

Starter

OFF

Condition (A)

Solenoid current cut status

Not cut

Battery voltage

11 V or higher

Target current

0.1 A or higher

Condition (B)

Battery voltage

8 V or higher

TYPICAL MALFUNCTION THRESHOLDS

When either condition below is met: Condition (A) or (B)

Condition (A)

Solenoid status from Hybrid IC

Failure

Condition (B)

Hybrid IC status

Failure

COMPONENT OPERATING RANGE

Output signal duty

Less than 100%

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

Shift solenoid valve SL1 turns ON/OFF normally when the shift lever is in D:

ECM gear shift command

1st

2nd

3rd

4th

5th

6th

Shift solenoid valve SL1

OFF

OFF

OFF

OFF

ON

ON

PROCEDURE

1.

INSPECT NO. 1 TRANSMISSION WIRE (SHIFT SOLENOID VALVE SL1)

(a) Disconnect the C39 No. 1 transmission wire connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

11 (SL1+) - 3 (SL1-)

20°C (68°F)

5.0 to 5.6 Ω

11 (SL1+) - Body ground

Always

10 kΩ or higher

3 (SL1-) - Body ground

Always

10 kΩ or higher
OK

2.

CHECK HARNESS AND CONNECTOR (NO. 1 TRANSMISSION WIRE - ECM)


(a) Disconnect the C53 ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

C53-14 (SL1+) - C53-15 (SL1-)

20°C (68°F)

5.0 to 5.6 Ω

C53-14 (SL1+) - Body ground

Always

10 kΩ or higher

C53-15 (SL1-) - Body ground

Always

10 kΩ or higher
OK

3.

INSPECT SHIFT SOLENOID VALVE SL1

(a) Remove shift solenoid valve SL1.



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

Standard Resistance:

Tester Connection

Condition

Specified Condition

1 - 2

20°C (68°F)

5.0 to 5.6 Ω

(c) Apply battery voltage (12 V) to the shift solenoid valve and check that the valve moves and makes an operating noise.

OK:

Measurement Condition

Specified Condition
  • Battery positive (+) with a 21 W bulb → Terminal 1
  • Battery negative (-) → Terminal 2

Valve moves and makes an operating noise
OK