Lexus IS250 IS220d GSE20 ALE20 - A960E AUTOMATIC TRANSMISSION
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 No. | DTC Detection Condition | Trouble Area |
| P0781 | 1-2 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:
| ECM command gearshift | 1st | 2nd | 3rd | 4th | 5th | 6th |
| Actual gear position under malfunction | ↑ | 1st | ↑ | 3rd | N* | N* |
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 conditions | 1st | 2nd | 3rd | 4th | 5th | 6th |
| Actual gear position under fail safe mode | ↑ (*1) | 1st (*1) | ↑ | 3rd | 3rd | 3rd |
- *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 output A "P0781" and other DTCs B
- HINT:
- If any other codes besides "P0781" are output, perform troubleshooting for those DTCs first.
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| 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 .
| Item | Test Details | Diagnostic 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) Press "→" button: Shift up Press "←" button: Shift down |
Possible to check the operation of the shift solenoid valves. |
- HINT:
| Tester command gear shift | 1st | 2nd | 3rd | 4th | 5th | 6th |
| Actual gear position under malfunction | ↑ | 1st | ↑ | 3rd | N* | N* |
N*: Neutral
- OK:
- Gear position changes in accordance with the tester command.
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| OK | |
| 3.PERFORM ACTIVE TEST BY INTELLIGENT TESTER (SHIFT SOLENOID VALVE SLT) |
- NOTICE:
- 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.
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.
| Item | Test Details |
| Activate the Solenoid (SLT)* | [Test Details] Operate the shift solenoid SLT and raise the line pressure. [Vehicle Condition] Vehicle Stopped. IDL: ON
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*: "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.
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| 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
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| OK | ||
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