Lexus IS250 IS220d GSE20 ALE20 - A960E AUTOMATIC TRANSMISSION

SYSTEM DESCRIPTION

MONITOR DESCRIPTION

INSPECTION PROCEDURE

CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0781)

PERFORM ACTIVE TEST BY INTELLIGENT TESTER

PERFORM ACTIVE TEST BY INTELLIGENT TESTER (SHIFT SOLENOID VALVE SLT)

CLEAR THE DTC AND RUNNING TEST

DTC P0781 1-2 Shift (1-2 Shift Valve)

SYSTEM DESCRIPTION


The 1-2 shift valve performs shifting to 1st gear and other gears.


Dtc P0781 1-2 Shift (1-2 Shift Valve). A960E AUTOMATIC TRANSMISSION. Lexus IS250 IS220d GSE20 ALE20
DTC No.DTC Detection ConditionTrouble Area
P07811-2 shift valve malfunction:
Shifting to 2nd and 4th gears is impossible. When the ECM directs the gearshift to switch to 5th or 6the gear, the engine overruns (clutch slips). (2-trip detection logic)
(a) and (b), or (a) and (c)
(a) When the ECM directs the gearshift to switch to 2nd gear, the actual gear is shifted to 1st.
(b) When the ECM directs the gearshift to switch to 4th gear, the actual gear is shifted to 3rd.
(c) When the ECM directs the gearshift to switch to 5th gear, the engine overruns (clutch slips).
Shift solenoid valve SLT remains open or closed
Valve body is blocked up or stuck (1-2 shift valve)
Automatic transmission (clutch, brake or gear, etc.)
  • HINT:
Gear positions in the event of a solenoid valve mechanical problem:
ECM command gearshift1st2nd3rd4th5th6th
Actual gear position under malfunction↑1st↑3rdN*N*
N*: Neutral
Gear position during fail-safe operation:
If any malfunction is detected, the ECM changes into the fail-safe mode to shift into the gear positions as shown in the table below.
Gear position under normal conditions1st2nd3rd4th5th6th
Actual gear position under fail safe mode↑ (*1)1st (*1)↑3rd3rd3rd
  • *1: Under engine braking, downshifting to 1st or 2nd gear is prohibited.

MONITOR DESCRIPTION

This DTC indicates that the 1-2 shift valve in the valve body is locked in the direction the spring compresses.


The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF" and switching oil pressure to the valves in the valve body.


The ECM calculates the "actual" transmission gear by comparing the signals from the input speed sensor (NT) and the output speed sensor (SP2). The ECM can detect many mechanical problems in the shift solenoids, valve body, and the transmission clutches, brakes, and gears. If the ECM detects that the actual gear position and the commanded gear position are different, it will illuminate the MIL and store the DTC .


INSPECTION PROCEDURE

1.CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0781)

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG) position.

Turn on the tester

Select the item "Powertrain / ECT / DTC / Current or Pending".

Read the DTCs using the intelligent tester.

  • Result:
  • Display (DTC output)Proceed to
    Only "P0781" is outputA
    "P0781" and other DTCsB
  • HINT:
  • If any other codes besides "P0781" are output, perform troubleshooting for those DTCs first.
B
GO TO DTC CHART
A
2.PERFORM ACTIVE TEST BY INTELLIGENT TESTER
  • HINT:
  • Performing the intelligent tester Active Test allows relay, Vacuum Switching Valve (VSV), actuator and other items to be operated without removing any parts. Performing the Active Test early in troubleshooting is one way to shorten labor time.
  • The Data List can be displayed the Active Test.

Warm up the engine.

Turn the engine switch off.

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG) position.

Turn on the tester.

Select the item "Enter / Powertrain / ECT / Active Test".

Follow the instructions on the tester and read the Active Test.

  • HINT:
  • While driving, the shift position can be forcibly changed with the intelligent tester.
  • Comparing the shift position commanded by the ACTIVE TEST with the actual shift position enables you to confirm the problem .
ItemTest DetailsDiagnostic Note
Control the Shift Position [Test Details]
Operate the shift solenoid valve and set each shift position by yourself.
[Vehicle Condition]
Less than 50 km/h (31 mph)
[Others]
Press "→" button: Shift up
Press "←" button: Shift down
 Possible to check the operation of the shift solenoid valves.
  • HINT:
This test can be conducted when the vehicle speed is 50 km/h (31 mph) or less.
The 4th to 5th and 5th to 6th up-shiftings must be performed with the accelerator pedal released.
The 6th to 5th and 5th to 4th down-shiftings must be performed with the accelerator pedal released.
Do not operate the accelerator pedal for at least 2 seconds after shifting and do not shift successively.
The shift position commanded by the ECM is shown in the DATA LIST (Shift Status) display on the intelligent tester.
Gear positions in the event of a solenoid valve mechanical problem:
Tester command gear shift1st2nd3rd4th5th6th
Actual gear position under malfunction↑1st↑3rdN*N*

N*: Neutral


  • OK:
  • Gear position changes in accordance with the tester command.
NG
REPLACE TRANSMISSION VALVE BODY ASSEMBLY
OK
3.PERFORM ACTIVE TEST BY INTELLIGENT TESTER (SHIFT SOLENOID VALVE SLT)
  • NOTICE:
Perform the test at the normal operating ATF (Automatic Transmission Fluid) temperature: 50 to 80°C (122 to 176°F)
Be careful to prevent SST hose from interfering with the exhaust pipe.
This check must be conducted after checking and adjusting engine.
Perform under condition that A/C is OFF.
  • HINT:
  • Performing the intelligent tester Active Test allows relay, Vacuum Switching Valve (VSV), actuator and other items to be operated without removing any parts. Performing the Active Test early in troubleshooting is one way to shorten labor time.
  • The Data List can be displayed during the Active Test.

Turn the engine switch off.

Lift the vehicle up.

Dtc P0781 1-2 Shift (1-2 Shift Valve). A960E AUTOMATIC TRANSMISSION. Lexus IS250 IS220d GSE20 ALE20

Remove the test plug on the transmission case center right side and connect SST.

  • SST
  • 09992-00095(09992-00231,09992-00271)

Lower the vehicle.

Fully apply the parking brake and chock the 4 wheels.

Connect the intelligent tester to the DLC3.

Start the engine.

Warm up the ATF (Automatic Transmission Fluid).

Measure the line pressure when the engine is idling.

Turn on the intelligent tester.

Select the item "Enter / Powertrain / ECT / Active Test".

Follow the instructions on the tester and perform the Active Test.

Measure the line pressure with SST.

ItemTest Details
Activate the Solenoid (SLT)*[Test Details]
Operate the shift solenoid SLT and raise the line pressure.
[Vehicle Condition]
Vehicle Stopped.
IDL: ON
  • HINT:
  • OFF: Line pressure up (When the active test of "Activate the Solenoid (SLT)" is performed, the ECM commands the SLT solenoid to turn off).
  • ON: No action (normal operation)

*: "Activate the Solenoid (SLT)" in the ACTIVE TEST is performed to check the line pressure changes by connecting the SST to the automatic transmission, which is used in the HYDRAULIC TEST as well.

  • HINT:
  • The pressure values in ACTIVE TEST and HYDRAULIC TEST are different from each other.
  • OK:
  • The line pressure changes as specified when performing the ACTIVE TEST.
NG
REPLACE SHIFT SOLENOID VALVE SLT
OK
4.CLEAR THE DTC AND RUNNING TEST

Clear the DTC, and check DTC again after conducting the "MONITOR DRIVE PATTERN FOR ECT TEST" .

  • OK:
  • No DTC code
NG
REPLACE TRANSMISSION VALVE BODY ASSEMBLY
OK
END
LEXUS IS250, IS220d / GSE20 ALE20
A960E AUTOMATIC TRANSMISSION
Lexus IS250 IS220d GSE20 ALE20
AUTOMATIC TRANSMISSION SYSTEM